2024 Volume 12 Pages 377-400
Resistant starch (RS) is a component of the starch fraction that is resistant to hydrolysis by gastric acid and hydrolysis by digestive enzymes in the small intestine, so it can reach the colon and be used as a source of prebiotics. Physical, chemical, and enzymatic modification technology and lactic acid bacteria (LAB) fermentation are the efforts used to increase RS and improve prebiotic properties in food ingredients. Physical modification is theoretically straightforward, but it consumes a lot of energy and has significant production costs. Chemical modification necessitates the employment of chemicals, which can lead to environmental issues due to strong acid waste, such as HCl. Enzymatic modification is ecologically favourable, although debranching pullulanase is scarce and costly. The combination of LAB fermentation with physical modification, such as autoclaving-cooling, can reduce energy consumption by lowering the number of autoclaving-cooling cycles while being ecologically benign and efficient in generating RS. RS holds significant promise for improving health outcomes, enhancing foods, and supporting sustainable food systems. However, challenges related to consumer awareness, regulatory approvals, food processing, and large-scale production need to be addressed to unlock their full potential. Continued research and development in this field, which is crucial in overcoming these barriers, should give us hope for the future of food technology. This review provides information and discusses in detail several physical, chemical, enzymatic, and fermentation modification technologies to increase RS and improve prebiotic properties in high-carbohydrate foods.
Flour and starch are a form of processing of high-carbohydrate foods such as cereals, tubers, and nuts. The use of flour and starch as functional food has yet to be utilized optimally, with most of it being used directly as a formulation in the manufacture of food products. Cassava starch is used as a binder, thickener, and structure enhancer in food [1], jack bean flour as a substitute for wheat flour in making biscuits [2]. Canna starch is a raw material for making vermicelli [3], and corn flour is an ingredient in the formulation for making cookies [4]. Flour and starch resulting from processed foods high in carbohydrates have the potential to be used as functional food ingredients. This is due to the presence of resistant starch (RS), which can be used as a source of prebiotics.
Starch is a polymer consisting of glucose sub-units. Based on its polymerization, starch can be divided into amylose and amylopectin [5]. Amylose is composed of α-glucose molecules with α-(1-4) glycoside bonds forming a linear chain. In comparison, amylopectin consists of amylose chains (α-(1-4) bonds) that are bound together to form branches with α-(1-6) glycoside bonds. Starch-based on the proportion of amylose and amylopectin, can be divided into three, namely waxy starch (containing 98–99% amylopectin), normal starch (containing 25–30% amylose), and high amylose starch (containing amylose > 50%) [6].
RS has the potential to be used as a functional food, namely a source of prebiotics. This is because RS has prebiotic activity that stimulates the growth of bacteria in the large intestine and provides health benefits. Lockyer and Nugent [5] reported that RS can affect bacteria in the intestine, where it acts as a prebiotic and plays a role in preventing colon cancer. In addition, RS is known to have a hypoglycemic effect, which can reduce blood sugar levels, increase insulin secretion, and increase insulin sensitivity [6]. The higher the RS content in a food sample, the lower the resulting glycemic index value [7]. This certainly encourages using local food as a functional food ingredient in Indonesia.
Prebiotics are food components that are beneficial for humans because they can stimulate the growth and activity of a number of probiotic bacteria in the colon, thereby improving the health of the human digestive tract. Prebiotics that have been widely commercialized are oligosaccharides, raffinose, and inulin in the form of supplements and functional foods [8]. The global market demand for prebiotic products continues to increase. Based on data from Global Market Insight, INC (Delaware, USA), the prebiotic market size is worth USD 6.2 billion in 2022 and is expected to increase based on a Compound Annual Growth Rate (CAGR) of 14.5% from 2023 to 2032 [9]. This encourages producers and researchers to innovate and develop new types of prebiotic products. One type of prebiotic that has potential as a source of prebiotics is RS. Wang et al. [10] reported that RS is a food ingredient that can selectively stimulate the growth of probiotic bacteria in the colon.
Starch modification and prebiotic sources are interrelated in the context of nutrition and food science. Starch modification refers to the process of altering the structure or properties of starch, which can affect its digestibility and its potential as a prebiotic. Prebiotics are substances that promote the growth of beneficial gut bacteria, typically non-digestible carbohydrates such as fibers and RS [5]. Starch modification has been used to design functional foods with added prebiotic benefits. Starches can be modified to enhance their prebiotic effects, such as increasing the amount of indigestible fiber content, altering the rate of fermentation, or selectively promoting the growth of beneficial probiotic bacteria. These include products enriched with RS or oligosaccharides derived from starch. Such foods are marketed for their ability to support digestive health by fostering a healthy microbiome. Starch modification can enhance the prebiotic potential of starch by increasing the formation of RS or oligosaccharides that are not easily digested but are fermented by beneficial gut bacteria. These prebiotic compounds help to improve gut health and contribute to the overall well-being of individuals consuming modified starches in functional foods. This review provides information and discusses in detail several physical, chemical, enzymatic, and fermentation modification technologies to increase RS and improve prebiotic properties in high-carbohydrate foods.
RS is categorized into five types based on its resistance to digestive enzymes [5]. RS type I (RS1) is a type of natural RS that is trapped in a cell matrix, such as the starch in legumes. Milling and chewing make RS1 readily available and less resistant to enzyme hydrolysis because it is free from the protein matrix [5]. RS type II (RS2) is a natural RS that has high resistance to enzyme hydrolysis, such as amylose-rich corn starch, raw potato starch, and raw banana starch [5, 6]. RS type III (RS3) is an RS that has undergone retrogradation due to repeated heating and cooling. Modification of natural RS to RS3 causes intra-molecular hydrogen bonds and starch chains to become more solid, leading to transformation to a continuous amorphous structure that allows less physical accessibility to digestive enzymes [5, 7]. Gelatinization and retrogradation substantially change the physical structure of the granule by affecting the physical integrity of the starch granule, as evidenced by swelling, cleavage, and melting of the granule, which limits the expansion of the starch granule and its contact with digestive enzymes [6, 7]. RS type IV (RS4) is starch that has undergone esterification and is modified by cross-linking with the addition of chemical compound derivatives [5]. RS type V (RS5) is the amylose fraction of starch that interacts with lipids and fatty acids [5].
Naturally, the levels of RS in each food ingredient are very low, and various increases in RS levels can be made using modification methods. Modification of flour and starch is one way to increase added value and obtain better properties or change certain properties [11]. The modification process, one of which is the physical modification, can increase the level of RS in a food ingredient. Faridah et al. [12] reported that the physical modification process for flour and starch is one method that is often used because it does not require chemicals. The process is simple compared to other modification methods. Autoclaving-cooling (AC), annealing, heat moisture treatment, and microwave-cooling are some physical modifications to increase RS. Apart from that, chemical modification with acid hydrolysis, enzymatic modification with the pullulanase enzyme, and fermentation modification with lactic acid bacteria can increase RS. Each modification has a different effect on RS levels. This is due to differences in the rate of gelatinization and retrogradation as well as hydrolysis of amylose amylopectin molecules in food ingredients. Increasing RS content through modification can be influenced by adjusting processing conditions, such as sample source and modification conditions.
The amylose ratio of amylopectin, distribution of the degree of polymerization (DP) of amylopectin chains, and the crystalline type of the sample contributed to the increase in RS content. Generally, the higher the amylose/amylopectin ratio, the higher the presence of RS. This is because the amylose chain structure is small and easy to orient and regenerate, while amylopectin has a dendritic structure and is difficult to orient [13]. The degree of polymerization of the amylopectin chain influences the rate of retrogradation. Faridah et al. [14] reported that the distribution of polymerization degrees 16–26 has a positive correlation with the retrogradation rate, while polymerization degrees 9–12 have a negative correlation. The more short-chain polysaccharide chains (DP 19-29) that are formed, the more RS levels will increase, and the levels of RS can be produced through the retrogradation process [15]. The crystalline type in the sample influences the increase in RS levels. Cahyana and Wijaya [16] reported that starch with crystalline type A shows slow digestion, while crystalline type B is resistant to digestive enzymes. The decrease in starch digestibility aligns with the increase in RS content.
Four types of starch compositions were analyzed based on their digestion times [15]. The first type of starch is called very rapidly digestible starch (VRDS), which is expressed as the amount of starch digested in the first minute by porcine pancreatin and amyloglucosidase [13, 14]. The second type of starch is called rapidly digestible starch (RDS), which is the amount of starch that can be digested and hydrolyzed between 1 minute and 20 minutes [15]. The third type of starch is slowly digestible starch (SDS), which is expressed as the amount of starch that can be digested between 20 and 120 minutes [15, 16]. Finally, RS is described as starch that cannot be digested after 120 minutes [14, 15].
Various studies related to physical, chemical, enzymatic, and fermentation modifications have been conducted to increase RS and improve prebiotic properties in flour and starch. Modification by applying high temperatures accompanied by high pressure causes a faster retrogradation rate, and cooling temperatures cause better retrogradation, thus affecting the amount of RS produced [17, 18]. Lintnerization modification (acid hydrolysis) can produce many linear amylose starch chains that are resistant to hydrolysis by digestive enzymes due to the formation of solid crystals, thus increasing the production of RS [19]. Modification with the pullulanase enzyme is able to break the α-1,6-glycosidic branching bonds by changing the structure and amount of short-chain amylose, thus increasing the levels of RS through crystallization [20]. Fermentation of lactic acid bacteria (LAB) producing amylase and pullulanase plays a role in reducing the DP value in starch so that short-chain amylose (DP 19–29) is obtained, which can be converted into RS [21].
AC 1 cycle modification on jack bean flour increases RS content by 18.45% [17]. Annealing modification on jack bean starch increased RS content by 17.98% [22]. Modification of heat moisture treatment on corn flour increased RS content by 7.01% [18]. Microwave-cooling modification of sago starch increased RS content by 55.66% [23]. Acid hydrolysis modification with HCl on sago starch increased RS content from 0.69% to 23.82% [19]. Enzymatic modification with pullulanase on waxy maize starch increased RS content from 3.9% to 18.04% [20]. Fermentation modification with L. plantarum B-307 on sorghum flour increased RS content from 4.85% to 27.31% [21]. This shows that physical, chemical, enzymatic, and fermentation modifications have the potential to increase RS levels significantly. Although the effect of modification on RS levels has been investigated, little information is available comparing the different modification mechanisms and linking them as a source of prebiotics.
3.1 Autoclaving-Cooling (AC) modificationThe modification process can increase RS in a food ingredient, including AC modification. AC modification is a physical modification that applies high temperature and pressure. The basic principle of the autoclaving-cooling modification is heating a starch suspension in water at a high temperature using an autoclave to increase the starch gelatinization process, then cooling it to produce short-chain amylose starch that is retrograded [24]. Short-chain amylose starch refers to a type of starch characterized by shorter chains of amylose. Amylose is a linear polymer of glucose units linked by α-1,4 glycosidic bonds. Amylose is one of the two main components of starch, the other being amylopectin, (which is highly branched). Due to its shorter chain length, the properties of short-chain amylose can differ from regular amylose. Composed of shorter chains of glucose compared to typical amylose. Meanwhile, standard amylose may have 300–600 glucose units, while short-chain amylose has significantly fewer glucose units, leading to altered physical and chemical properties. Shorter amylose chains may be more readily digestible than longer amylose chains. However, depending on the structure and processing, it could still exhibit some resistance to digestion, potentially contributing to the formation of RS (a type of prebiotic). Short-chain amylose typically has a lower tendency to form strong gels compared to longer-chain amylose, as its shorter chains do not aggregate as effectively. It may have a faster retrogradation rate, meaning it can recrystallize more quickly after gelatinization, which is important for applications involving texture and shelf-life in food products. Short-chain amylose starch can be used in various food applications where specific textural properties or digestive profiles are desired, such as in functional foods aimed at improving gut health or managing blood glucose levels.
| Foodstuffs | Modified condition | Control RS (%) | Modified RS (%) | References |
|---|---|---|---|---|
| Sago starch | AC cycle: 3 cycles Heating time: 30 minutes Heating temperature: 121 °C Cooling temperature: 4 °C |
0.69 | 24.27 | [19] |
| Taro starch | AC cycle: 2 cycles Heating time: 15 minutes Heating temperature: 121 °C Cooling temperature: 4 °C |
1.25 | 4.38 | [25] |
| Taro starch | AC cycle: 1 cycle Heating time: 15 minutes Heating temperature: 121 °C Cooling temperature: 4 °C |
1.25 | 3.63 | [25] |
| Jack bean flour | AC cycle: 1 cycle Heating time: 15 minutes Heating temperature: 121 °C Cooling temperature: 4 °C |
23.17 | 27.45 | [17] |
| Corn starch | AC cycle: 2 cycles Heating time: 30 minutes Heating temperature: 121 °C Cooling temperature: 4 °C |
15.27 | 32.54 | [14] |
| Corn flour | AC cycle: 2 cycles Heating time: 30 minutes Heating temperature: 121 °C Cooling temperature: 4 °C |
15.84 | 27.78 | [14] |
| Taro flour | AC cycle: 1 cycle Heating time: 15 minutes Heating temperature: 121 °C Cooling temperature: 4 °C |
4.13 | 7.92 | [26] |
| Taro flour | AC cycle: 2 cycles Heating time: 15 minutes Heating temperature: 121 °C Cooling temperature: 4 °C |
4.13 | 11.15 | [26] |
| Sorghum flour | AC cycle: 3 cycles Heating time: 15 minutes Heating temperature: 121 °C Cooling temperature: 4 °C |
4.85 | 18.86 | [21] |
| Cassava flour | AC cycle: 3 cycles Heating time: 15 minutes Heating temperature: 121 °C Cooling temperature: 4 °C |
2.8 | 11.5 | [27] |
The AC process at heating above the gelatinization temperature results in the dissociation of hydrogen bonds from the double helix structure of amylopectin, melting of the crystallites, and releasing the amylose fraction from the granules. The amylose fraction then forms a double helix structure and bonds with other double helices to form crystallites so that the amylose recrystallizes and forms RS 3 [28]. High-temperature heating and cooling processes are carried out to facilitate the retrogradation process [19]. AC modification with several cycles is known to cause more retrograded starch to be formed, as indicated by the increase in RS levels. Rosida et al. [29] reported that adding cycles is expected to increase the formation of the short-chain amylose fraction and the amount of amylose that undergoes retrogradation, producing more RS.
Adjusting processing conditions, such as modification conditions, can influence RS levels. Increasing the number of cycles in AC has a positive effect on RS levels but a negative effect on the formation of simple sugars. According to Faridah et al. [14], The number of AC cycles can increase the depolymerization of long-chain amylose into short-chain fractions and the breaking of amylose chains into simple sugars. Simple sugars can slow down the retrogradation process, thereby influencing the formation of RS [30]. Besides the number of cycles, autoclave temperature and time influence RS levels. This is in line with Dupuis et al. [31] that the temperature in the autoclave process affects the levels of RS. Meta-analysis studies show that a heating time of 30 minutes and an autoclave temperature of 121 °C significantly increase RS levels [14]. Several studies have been conducted on physical modification to increase RS with autoclaving-cooling technique (Table 1).
3.2 Annealing modificationAnnealing is a hydrothermal modification where starch or flour samples are given an excess water content of 40–60% for a certain time and between the glass transition and gelatinization temperatures [32]. The basic principle of annealing modification, namely the occurrence of partial gelatinization due to the heating process below the gelatinization temperature for a long time, thus destroying the hydrogen bonds that are formed, and when retrograded, the hydrogen bonds will re-associate. Physical modification, such as annealing, is effective in changing the structure and function of starch, which does not produce hazardous chemical waste, is cost-effective and environmentally friendly [33].
| Foodstuffs | Modified condition | Control RS (%) | Modified RS (%) | References |
|---|---|---|---|---|
| Arrowroot starch | Incubation temperature: 65 °C Incubation time: 24 hours |
3.17 | 9.23 | [34] |
| Arrowroot starch | Incubation temperature: 55 °C Incubation time: 24 hours |
3.17 | 6.17 | [34] |
| Jack beans starch | Incubation temperature: 55 °C Incubation time: 24 hours |
3.11 | 3.67 | [22] |
| Corn flour | Incubation temperature: 50 °C Incubation time: 24 hours |
4.42 | 39.52 | [18] |
| Water caltrop starch | Incubation temperature: 65 °C Incubation time: 24 hours |
37.52 | 38.63 | [35] |
| Yellow sweet potato starch | Incubation temperature: 45 °C Incubation time: 24 hours |
24.1 | 28.8 | [36] |
| White sweet potato starch | Incubation temperature: 45 °C Incubation time: 24 hours |
24.0 | 29.2 | [36] |
| Purple sweet potato starch | Incubation temperature: 45 °C Incubation time: 24 hours |
25.3 | 32.0 | [36] |
| Chinese yam starch | Incubation temperature: 50 °C Incubation time: 24 hours |
15.64 | 17.88 | [37] |
| Chinese yam flour | Incubation temperature: 50 °C Incubation time: 24 hours |
16.88 | 18.40 | [37] |
Annealing modification allows the reorganization of the starch structure in crystalline and amorphous lamellae without changing the crystalline order, which will increase granule stability and the RS content [38]. According to Tanaka et al. [39], there are several changes in the characteristics of starch in the annealing process, including increased granule stability, refinement of the crystal structure, interaction of starch chains in the amorphous and crystalline parts, formation of a double helix structure, increase in gelatinization temperature, narrowing of the gelatinization temperature range, decrease in the ability to expand starch, and a decrease in the amount of dissolved amylose. The formation of RS after annealing treatment is caused by interactions between amylose-amylose and amylose-amylopectin chains and regular structural rearrangements observed by changes in physicochemical properties [36]. This is proven through research by Setiarto et al. [18], where the annealing process with an incubation temperature of 50 °C and an incubation time of 24 hours increased RS by 8.9 times compared to the control (native) treatment (Table 2).
Meta-analysis studies show that annealing techniques significantly increase RS levels in high-carbohydrate foods [40]. This is in line with other meta-analysis studies, which show that an incubation temperature of 50–54 °C and an incubation time of 24 hours significantly increase RS levels [41]. Several studies have been conducted on physical modification to increase RS with annealing techniques (Table 2).
3.3 Heat moisture treatment modificationIncreasing RS can be done by modifying Heat Moisture Treatment (HMT). HMT is a treatment that modifies starch using controlled low water content <35%, high temperature (84–120 °C), and heating time ranging from 15 minutes to 16 hours [42]. HMT modification encourages retrogradation and the formation of RS 3. The basic principle of HMT modification, namely heat treatment with low water content, triggers partial gelatinization, which can induce the breaking of hydrogen bonds in starch and continue the retrogradation process for the reassociation of hydrogen bonds in starch [43]. Water content has an important role in RS formation during HMT. Liu et al. [44] reported that water can form hydrogen bonds between molecules in starch granules and reorganize molecular chains to form double helices so that the water content before modification makes it possible to increase the level of RS. Besides the moisture content factor, temperature treatment also influences the increased RS content.
| Foodstuffs | Modified condition | Control RS (%) | Modified RS (%) | References |
|---|---|---|---|---|
| Purple sweet potato starch | Heating temperature: 100 °C Heating time: 6 hours Moisture content: 35% |
25.3 | 35.4 | [36] |
| Jack bean starch | Heating temperature: 110 °C Heating time: 16 hours Moisture content: 30% |
3.11 | 3.89 | [22] |
| Mung bean starch | Heating temperature: 120 °C Heating time: 16 hours Moisture content: 30% |
6.85 | 38.36 | [45] |
| Chinese yam starch | Heating temperature:100 °C Heating time: 10 hours Moisture content: 20% |
15.64 | 20.07 | [37] |
| Chinese yam flour | Heating temperature: 100 °C Heating time: 10 hours Moisture content: 20% |
16.88 | 21.28 | [37] |
| White sorghum starch | Heating temperature: 100 °C Heating time: 16 hours Moisture content: 25% |
19.33 | 19.97 | [46] |
| Corn flour | Heating temperature: 120 °C Heating time: 3 hours Moisture content: 20% |
4.42 | 4.73 | [18] |
| Rice starch | Heating temperature: 120 °C Heating time: 12 hours Moisture content: 30% |
3.26 | 7.71 | [47] |
| Potato starch | Heating temperature: 110 °C Heating time: 8 hours Moisture content: 30% |
22.5 | 28.5 | [48] |
| Cassava starch | Heating temperature:110 °C Heating time: 8 hours Moisture content: 30% |
20.3 | 26.6 | [48] |
Brahma and Sit [49] reported that the increase in RS content may be caused by high temperature and water content treatment, which encourages the formation of hydrogen bridges between starch molecules and makes the structure denser and more compact. Another factor in the modification conditions that influences the increase in RS content is heating time. Higher heating times may contribute to an increase in RS. This is in line with research by Barua and Srivastav [45], which reported that modifying green bean starch with HMT at a higher temperature (120oC) and heating time (16 hours) can increase RS with an increase percentage of 459.9%. Meta-analysis studies show that the highest increase in RS levels in various carbohydrate sources is influenced by the interaction of 15–25% moisture content, 0.25–6 hours heating time, and 120–130 °C heating temperature [42]. Several studies have been conducted on physical modification to increase RS with HMT techniques (Table 3).
3.4 Microwave heat treatment modificationMicrowave heating followed by cooling can increase the gelatinization temperature and induce the formation of RS3 [50]. The basic principle of microwave heat treatment modification, namely utilizing heat generated from microwaves to induce gelatinization and regeneration of hydrogen bonds in starch through retrogradation, can reduce starch digestibility. Microwave heating can increase levels of RS because microwaves can reduce starch digestibility through gelatinization [51]. The increase in RS content with heating treatment is caused by gelatinization and regeneration of hydrogen bonds in starch during the retrogradation process [52]. After starch is gelatinized (heated and water-absorbed), it may retrograde upon cooling, forming a more crystalline structure. When reheated, this retrograded starch can undergo a phase transition again, which has its distinct temperature, often higher than the initial gelatinization temperature. This second heating does not imply a complete repeat of the original gelatinization process but rather the disruption of the retrograded structure.
This process triggers the formation of RS3 starch. Microwaves can induce the swelling stage of starch gelatinization, and then the cooling process will reduce the temperature while inducing starch recrystallization. The molecular chains recombine through hydrogen bonds to form new crystals, which causes retrogradation [51]. During the retrogradation process, the amylose and amylopectin molecular chains in the pie granules begin to recombine to form a denser and more ordered structure, thereby increasing the levels of RS [53].
| Foodstuffs | Modified condition | Control RS (%) | Modified RS (%) | References |
|---|---|---|---|---|
| Proso millet starch | Heating time: 10 minutes Power: 500 W |
11.5 | 18.7 | [54] |
| Water caltrop starch | Heating time: 50 seconds Power: 800 W |
64.40 | 67.41 | [55] |
| Corn starch | Heating time: 90 seconds Power: 800 W |
62.0 | 65.2 | [56] |
| Potato starch | Heating time: 90 seconds Power: 800 W |
64.2 | 66.3 | [56] |
| Chestnut starch | Heating time: 90 seconds Power: 800 W |
73.4 | 74.3 | [56] |
| Corn flour | Heating time: 13 minutes Power: 399 W |
4.42 | 6.04 | [18] |
| Sorghum starch (Hongnuo) | Heating time: 6 minutes Power: 600 W |
7.62 | 9.13 | [53] |
| Elephant foot yam starch | Heating time: 120 seconds Power: 600 W |
29.88 | 40.37 | [57] |
| Potato starch | Heating time: 300 seconds Power: 206 W |
65.91 | 67.17 | [58] |
| Potato starch | Heating time: 5 minutes Power: 400 W |
13.69 | 14.97 | [59] |
High power can influence the formation of amorphous crystal structures that are more resistant to digestive enzymes. According to Li et al. [52], High temperatures can open the bonds between starch molecules and form new structures that are denser and more compact. High power usage also contributes to the degradation of RS1 and RS2 so that the total RS3 can decrease [49]. This aligns with Tao et al. [60] that short and medium amylose chains in starch can be excessively broken if excessive power is used. In addition to microwave power, heating time contributes to increased RS levels.
Kim et al. [61] reported that increasing heating time can increase the mobility of starch chains, which can cause an increase in RS. Meta-analysis studies show that microwaves with a power of 401–600 W and a heating time of 60–99 seconds in the cereal food group significantly affect increasing levels of RS [51]. Several studies have been conducted on physical modification using microwave techniques to increase RS (Table 4).
3.5 Acid hydrolysis modificationChemical modifications such as acid hydrolysis modification can increase levels of RS. Raungrusmee and Anal [62] reported that acid hydrolysis or lintnerization of the α-1,4 and α-1,6 glycosidic bonds of amylose and amylopectin produces RS3 (lintnerized starch). This is in line with research by Syafii et al. [63] which reported that the addition of hydrochloric acid to starch can randomly hydrolyze or break the glycosidic bonds in amylose and amylopectin molecules so that it can inhibit the activity of the α-amylase enzyme in the hydrolysis process. Agustina et al. [64] reported that starch modification through acid hydrolysis is different from enzymatic hydrolysis, where in acid hydrolysis, the glycosidic bonds are randomly hydrolyzed, and in enzymatic hydrolysis with the pullulanase enzyme only hydrolyzes the α-1,6 bonds in the amylopectin fraction.
Kusnandar et al. [19] reported that the basic principle of acid hydrolysis modification is a two-stage attack on starch granules, namely a fast attack on the amorphous area and a slow attack on the crystalline area of the amylopectin fraction with mineral acid to form a short-chain amylose fraction. This shows that the acid hydrolysis modification works not specifically, where not only can the amylopectin chain be broken, but it can also break the amylose chain into short-chain amylose. The greater the short-chain amylose fraction, the greater the possibility of increasing the formation of RS3 during modification. This is in line with Khoozani et al. [65], who stated that the increase in RS content with lintnerization treatment was caused by the disruption of the amorphous areas by acid, which caused an increase in the ratio of crystalline parts that were more difficult to access by enzymes. Several studies have been conducted on chemical modification to increase RS with acid hydrolysis modification (Table 5).
| Foodstuffs | Modified condition | Control RS (%) | Modified RS (%) | References |
|---|---|---|---|---|
| Sago starch | 1% HCl hydrolysis at 40 °C for 24 hours | 0.69 | 23.82 | [19] |
| Sago starch | 2% HCl hydrolysis at 40 °C for 24 hours | 0.69 | 13.98 | [19] |
| Rice starch | 2 N HCl hydrolysis at 40 °C for 3 hours | 8.44 | 40.19 | [62] |
| Rice starch | 1.5 N HCl hydrolysis at 40 °C for 3 hours | 8.44 | 22.99 | [62] |
| Rice starch | 1 N HCl hydrolysis at 40oC for 3 hours | 8.44 | 13.73 | [62] |
| Corn flour | 2.2 N HCl hydrolysis at 35 °C for 2 hours | 4.42 | 23.98 | [18] |
| Banana flour | 2.2 N HCl hydrolysis at 35 °C for 2 hours followed by autoclaving-cooling 1 cycle | 15.54 | 30.39 | [63] |
| Daluga corm starch | 2.2 N HCl hydrolysis at 35 °C for 2 hours followed by pullulanase debranching and autoclaving-cooling 1 cycle | 3.40 | 40.47 | [64] |
| Daluga corm starch | 2.2 N HCl hydrolysis at 35 °C for 2 hours followed by pullulanase debranching and autoclaving-cooling 3 cycles | 3.40 | 31.12 | [64] |
| Rice flour | 0.2 M HCl hydrolysis at 35 °C for 8 hours | 3.69 | 5.75 | [66] |
Acid hydrolysis modification is a chemical modification that involves exposing mineral acids such as H2SO4, HCl, HNO3, and H3PO4 to starch below the gelatinization temperature. Pratiwi et al. [43] reported that in modification acid hydrolysis, the hydroxonium ion attacks the oxygen in the glycosidic bond and then hydrolyzes the bond. Modifying acid hydrolysis can decrease swelling ability and increase solubility and the degree of crystallinity [67]. In addition, amylose levels tend to decrease as the acid hydrolysis process takes longer. This is in line with Atichokudomchai et al. [66], which reported that the decrease in amylose content during acid hydrolysis is caused by the action of acid on the amorphous regions of starch where amylose is located. Raungrusmee and Anal [62] reported that the RS content was observed to increase significantly in the lintnerization treatment, so the RS content increased with an increase in hydrochloric acid concentration. This shows that the longer and higher the acid concentration used in acid hydrolysis will influence the decrease in amylose levels. Reducing amylose levels will increase the degree of crystallinity, affecting starch digestibility and increasing RS levels.
3.6 Debranching pullulanase enzymatic modificationEnzymatic modification is a widely used alternative modification of starch or flour. Ainezzahira et al. [68] reported that enzymatic modification is safer for human health and the environment, and the reaction is easily controlled. Witono and Juliani [69] reported that enzymatic modification with pullulanase was more effective in increasing RS levels than acid hydrolysis and autoclaving-cooling. Bodjrenou et al. [70] reported that enzymatic modification with pullulanase debranching results in short linear chains being released from amylopectin, thus changing the physicochemical properties and digestibility of starch and forming RS. This shows that pullulanase debranching modification can increase the RS content of food ingredients.
The basic principle of enzymatic modification is the hydrolysis of starch molecular chains facilitated by specific debranching enzymes to form short linear starch molecules, where these short molecules contribute to the increase of high RS content [43]. The pullulanase enzyme is a commonly used debranching enzyme for flour or starch modification. Pullulanase (pullulan 6-glucanohydrolase, EC 3.2.1.41) is a microbial enzyme produced by Lactobacillus plantarum, Lactobacillus fermentum, Bacillus halodurans, and Klebsiella pneumoniae through fermentation process [15]. Pullulanase is one of the debranching enzymes that cleave the α-1,6 linkage in pullulan, amylopectin, and other polysaccharides [43]. Pullulanase enzyme works specifically in hydrolyzing starch molecular bonds, which can only hydrolyze the α-1,6 bond in the amylopectin fraction. This makes the enzymatic modification process easier to control, where the debranching process can be carried out with certain specific debranching enzymes.
| Foodstuffs | Modified condition | Control RS (%) | Modified RS (%) | References |
|---|---|---|---|---|
| Indica rice starch | Debranching with α-amylase at 80 °C for 40 minutes and pullulanase at 46 °C for 12 hours | 2.52 | 47.0 | [71] |
| Corn flour | Debranching with α-amylase and pullulanase at 50 °C for 16 hours | 1.8 | 24.3 | [72] |
| Waxy maize starch | Debranching with pullulanase concentration 10.6 U/g at 50 °C for 5 hours |
3.9 | 18.04 | [20] |
| Green banana flour | Debranching with amylopullulanase at 50 °C for 12 hours | 38.5 | 68.99 | [73] |
| Purple sweet potato starch | Debranching with pullulanase concentration 10 NPUN/g at 60 °C for 15 hours | 60.51 | 70.14 | [70] |
| Rice flour | Debranching with pullulanase at 60 °C for 2 hours | 3.69 | 6.43 | [69] |
| Rice flour | Debranching with pullulanase at 60 °C for 8 hours | 3.69 | 7.61 | [69] |
| Corn flour | Debranching with pullulanase concentration 10.4U/g at 50oC for 24 hours | 4.42 | 17.16 | [18] |
The debranching enzyme is the most commonly used approach to increase the content of type 3 RS [70]. Pullulanase enzyme can hydrolyze the α-1,6 branching bond in amylopectin, increasing the short-chain linear fraction [64]. This short-chain linear fraction will undergo retrogradation, where rearrangement occurs to form a compact, organized structure, making it more resistant to hydrolysis by digestive enzymes. According to Pratiwi et al. [43], pullulanase debranching modification combined with autoclaving-cooling will allow retrogradation of short linear molecules that can increase RS content. This is in line with Milasinovic et al. [74], who reported that fast and efficient enzymatic hydrolysis requires pre-swelling and full gelatinization, which can be done with an autoclave. In addition, Setiarto et al. [18] added that after modification of debranching pullulanase, autoclaving-cooling 1 cycle was performed for enzyme inactivation.
Generally, RS content is influenced by the concentration of the pullulanase enzyme and the incubation time during the branching process. Isra et al. [75] reported that a long incubation time in the enzymatic debranching process can increase RS levels. This is in line with the research of Witono and Juliani [69], who reported that RS levels increased with an increase in enzymatic hydrolysis incubation time. In addition, enzyme concentration influences RS content. Faridah et al. [76] reported that the higher the concentration of pullulanase enzyme, the more α-1,6 amylopectin branching points were cut off so that the chance of hydrolyzing glucan chains from cutting amylopectin branching points increased during the AC process and caused a decrease in glucan chain length. This is in line with the research of Miao et al. [77], which reported that RS3 levels increased with increasing concentration of pullulanase enzyme used. Several studies have been conducted on enzymatic modification to increase RS with pullulanase debranching modification (Table 6).
3.7 Lactic acid bacteria fermentation modificationIncreasing RS can be done by modifying LAB fermentation. Some LABs can produce amylase and pullulanase enzymes to hydrolyze starch components during fermentation. Isolates of Lactobacillus plantarum B-307 and Leuconostoc mesenteroides SU-LS67 have high amylase and pullulanase enzyme activities [78]. Setiarto et al. [26] reported that the culture mixture of Lactobacillus plantarum D-240 and Leuconostoc mesenteroides SU-LS67 had amylase (2.53 U/mL) and pullulanase (2.81 U/mL) activities. In addition, Faozi et al. [79] reported that L. casei has an amylase activity of 0.93 U/mL. The activity of amylase and pullulanase enzymes can increase with the length of fermentation time [80]. Amylase and pullulanase enzymes are known to have the ability to hydrolyze starch linear α-1,4 glycosidic bonds in amylose and α-1,6 glycosidic branching bonds in amylopectin. Bhanwar and Ganguli [81] reported that amylase is able to hydrolyze linear α-1,4 glycosidic bonds in amylose, randomly producing short-chain amylose and simple sugars. Meanwhile, Vatanasuchart et al. [82] reported that pullulanase hydrolyzes the α-1,6 branching bond connecting amylopectin so that short-chain amylose is produced. The short-chain amylose formed ultimately has a crystalline shape with stronger bonds, where the bond is difficult to hydrolyze by digestive enzymes, which causes modified starch to be indigestible in the digestive tract so that it can be referred to as RS [83]. Several studies have been conducted on fermentation modification to increase RS with LAB fermentation modification (Table 7).
The basic principle of LAB fermentation modification is the hydrolysis of starch molecular chains through amylase and pullulanase enzymes produced by certain LAB to form short-chain amylose, where these short molecules contribute to increasing high levels of RS. Setiarto et al. [26] reported that taro fermentation with mixed cultures (L. plantarum D-240 and Leuconostoc mesenteroides SU-LS 67) for 18 hours resulted in a DP value of 27.13, which was eligible to form RS (DP 19-29). During the fermentation process, total starch levels decreased, which had an impact on increasing sugar levels, reducing sugar levels, and decreasing amylose levels. Setiarto et al. [27] reported that fermentation treatment also reduces total cassava starch levels because lactic acid bacteria utilize cassava starch components, namely amylose and amylopectin, as carbon source nutrients for growth. The increase also influences the increase in reducing sugar in short-chain amylose, which is measured as reducing sugar [84].
Khan et al. [85] added that a decrease in total starch content has an impact on increasing reducing sugar levels and decreasing amylose levels. The decrease in amylose content is caused by the hydrolysis of amylose by enzymes produced by LAB into glucose and maltose, which are reducing sugars [86]. The decrease in amylose content affects the RS content, where the lower the amylose content, the lower the potential for RS formation [87].
| Foodstuffs | Modified condition | Control RS (%) | Modified RS (%) | References |
|---|---|---|---|---|
| Cassava flour | Culture fermentation of Leuconostoc mesenteroides SU-LS 67: Lactobacillus plantarum B-307 (1:1) 2% (v/v) for 18 hours | 2.8 | 3.9 | [27] |
| Sorghum flour | Fermentation of 2% (v/v) Lactobacillus plantarum B-307 culture for 18 hours | 4.85 | 27.31 | [21] |
| Taro flour | Culture fermentation of Lactobacillus plantarum D-240: Leuconostoc mesenteroides SU-LS-67 (1:1) 2% (v/v) for 18 hours | 4.13 | 3.82 | [26] |
| Daluga flour | Fermentation of 2% (v/v) Lactobacillus plantarum BSL culture for 18 hours | 4.70 | 6.00 | [12] |
| Purple sweet potato flour | Culture fermentation of Leuconostoc mesenteroides SU-LS 67: Lactobacillus plantarum B307 (1:1) 2% (v/v) for 24 hours | 2.11 | 2.45 | [88] |
| Yam flour | Culture fermentation of Leuconostoc mesenteroides SU-LS 67: Lactobacillus plantarum D-240 (1:1) 2% (v/v) for 24 hours | 2.14 | 2.22 | [86] |
| Beneng taro flour | Culture fermentation of Lactobacillus casei : Streptococcus thermophilus (1:1) 2% (v/v) for 24 hours | 3.26 | 4.51 | [79] |
One of the effective efforts to increase RS levels is through a combination of fermentation and autoclave-cooling treatments. This is because this combination can increase the opportunity for short-chain amylose to retrograde to form RS [89]. Increasing RS levels means that starch hydrolysis does not reach glucose monosaccharide because the fermentation process only aims to cut amylose and amylopectin chains into shorter chains [21].
RS is the starch fraction that is resistant to digestion in the small intestine, so it can reach the large intestine intact [5]. After reaching the colon, RS undergoes anaerobic fermentation by gut microbiota [87, 89]. This fermentation process produces short-chain fatty acids (SCFAs), mainly acetate, propionate, and butyrate, as well as certain gases (hydrogen, methane, and carbon dioxide) [90]. One of these SCFAs, butyrate, is known to play an important role in colon health, serving as an energy source for colonocytes, has anti-inflammatory properties, and potentially reduces the risk of colon cancer [91]. In addition, SCFAs modulate colon pH, which supports the growth of beneficial microbiota while inhibiting the proliferation of pathogenic strains.
| Type RS | Duration and dose | Population | Microbial groups showing alterations | References |
|---|---|---|---|---|
| RS 3 | 3 weeks, 25,56 g/day | 14 overweight men | Increased: Ruminococcus bromii, Eubacterium rectale |
[92] |
| RS 3 | 3 weeks, 20 g/day | 14 obese men | Increased: Ruminococcaceae Decreased: Papillibacter cinnamivorans |
[93] |
| RS 2 | 2 weeks, 20-34 g/day | 174 healthy young adults | Increased: Ruminococcus bromii, Clostridium chartatabidum, Eubacterium rectale |
[94] |
| RS 2 | 1 week, 14-19 g/day | 30 healthy adults | Increased: Ruminococcus, Gemmiger |
[95] |
| RS 2 | 3 weeks, 24 g/day | 20 young adults | Increased: Bifidobacterium adolescentis, Ruminococcus bromii, Eubacterium rectale |
[96] |
Source: Wang et al. [87]
Fermentation of RS has an interesting aspect in terms of its selectivity. Walker et al. [92] reported that not all gut microbiotas can effectively ferment RS. Currently, the gut microbiota known to degrade RS in the colon effectively is Ruminococcus bromii and Bifidobacterium adolescentis [97]. Metabolites produced from the fermentation of RS by gut microbiota can serve as substrates for the growth of other microbiota populations. This process is referred to as cross-feeding. Ruminococcus bromii plays an important role in degrading RS to produce SCFAs and promotes the reproduction of other beneficial microbiota through cross-feeding [98]. This suggests that RS impacts the gut microbiota in two ways. The first involves the direct effect of RS on the gut environment by increasing beneficial microbiota and inhibiting pathogenic microbiota. The second aspect indirectly affects the gut microbiota through increased SCFA production.
The International Scientific Association of Probiotics and Prebiotics in 2017 defined prebiotics as substrates that are selectively utilized by host microorganisms and provide health benefits [99]. Bindels et al. [100] and Setiarto et al. [15] reported that RS contained in food ingredients can be claimed to have prebiotic properties because it has met the following requirements: resistant to gastric acid and not hydrolyzed by digestive enzymes, not absorbed in the upper part of the gastrointestinal tract, can be a selective substrate for the growth of probiotic bacteria in the colon, cannot be utilized for the growth of enteropathogenic bacteria and can increase the number and activity of microflora that support the health of the digestive tract.
Changes in human gut microbiota detected after RS intervention can be seen in (Table 8). Some research studies showed that RS increased the number of Bifidobacterium and Ruminococcus bacteria [87]. Bifidobacterium and Ruminococcus are the dominant microbiota in the human intestinal tract, where they strongly influence the function of the entire host microbiome. Baxter et al. [94] reported that the increase in Ruminococcus is closely related to the increase in butyrate concentration, where butyrate is known to have an important role in colon health.
RS is one of the substrates used for colonic fermentation, mainly performed by gut microbiota. SCFAs are the main metabolites that support the benefits of prebiotics [101]. Acetate, propionate, and butyrate are the main SCFAsthat account for 90% of SCFAs produced by gut microbiota [102]. SCFAs are produced mainly in the cecum and proximal colon, and their concentration decreases from the proximal to distal colon as the substrate used for fermentation is gradually depleted [103]. According to McLoughlin et al. [104], one of the factors affecting SCFA production is the substrate source. Research by Qin et al. [105] reported that RS5 produced more butyric acid than RS2 and RS3.
| Bioactivities of SCFAs | Effects and mechanisms |
|---|---|
| Anti-inflammation | SCFAs show good anti-inflammatory activity. Their main mechanisms of action include inhibiting the production of pro-inflammatory mediators, such as IL-6 and TNF-α, and increasing the production of anti-inflammatory mediators, such as IL-10, TGF-β, and annexin A1. |
| Anti-obesity | SCFAs have an anti-obesity effect, with a mechanism involving appetite suppression, inhibiting lipogenesis, and inducing browning in white adipose tissue. |
| Anti-diabetes | SCFAs can prevent and manage diabetes mellitus through increased insulin sensitivity, glucose homeostasis, and suppression of liver gluconeogenesis. |
| Anti-cancer | SCFAs are potential agents against several types of cancer, such as cervical, colorectal, melanoma, and liver cancers. Their mechanism of action mainly includes inhibiting the proliferation of cancer cells, stopping the cell cycle, reducing inflammation, reducing metastasis, and enhancing the effects of immunotherapy. |
| Hepatoprotection | SCFAs play a positive role in non-viral liver disease. Its mechanism of action includes maintaining the intestinal epithelial barrier, regulating lipid metabolism and inflammatory responses in the liver, improving mitochondrial efficiency, and promoting the maturation of Cytochrome p450 (CYP). |
| Cardiovascular protection | SCFAs can be a potential therapeutic strategy to prevent and manage cardiovascular disease (CVD) by lowering blood lipids and blood pressure, reducing ischemia/reperfusion-related injuries (IRIs), and improving myocardial infarction (MI) injuries. |
| Neuroprotection | SCFAs, such as acetate, can help prevent and manage neurodegenerative and neuropsychiatric diseases. |
| Immuno regulation | SCFAs participate in immune system function through reduced migration and activation of dendritic cells to relieve allergies and promote T and B cell differentiation to regulate antigen-specific adaptive immunity. The immunoregulatory action of SCFA is mainly achieved by directly binding to the G-protein receptor 41 (GPR41) paired receptor on the cell surface and entering the cell to regulate cell metabolism and inhibit histone deacetylase (HDAC). |
Source: Xiong et al. [106]
Approximately 90% of SCFAs are absorbed by the intestinal cavity and metabolized by colonocytes or the liver [104]. Butyrate is an important energy source for colonocytes. In contrast, only a small amount of butyrate reaches the liver system, and other SCFAs (acetate and propionate) that colonocytes have not metabolized can reach the liver through the portal vein [107]. The liver is the main site for SCFA metabolism in humans, with approximately 40% of acetate and 80% of propionate in the portal vein utilized and metabolized by the liver [108]. The benefits of SCFAs can also explain the benefits of prebiotics. This is because prebiotics are used as substrates for fermentation in the colon through gut microbiotas that produce SCFA metabolites. The bioactivity of SCFAs and the benefits of SCFAs are described in Table 9.
The prebiotic index is the increase in probiotic bacteria population correlated with the number of prebiotics. Probiotic LAB utilizes nutrients from flour or modified starch as a carbon source for growth. This was proven through the research of Venkataraman et al. [96] that the presence of RS2 can stimulate the growth of colon bacteria (Bifidobacterium adolescentis, Ruminococcus bromii, Eubacterium rectale). This is in line with Sousa et al. [109], who reported that yakon tuber flour can stimulate probiotic bacteria, as evidenced by the increased production of short-chain fatty acids that are beneficial to health.
According to Imelda et al. [110], food ingredients are declared as a good source of prebiotics if they have an effect value and a prebiotic index above 2.0. According to Putra [111], banana flour's prebiotic index (0.91–0.94) can be developed into synbiotic products by utilizing L. plantarum as a probiotic. The probiotic bacteria L. acidophilus has a higher prebiotic index than L. plantarum [112]. This shows that each LAB has different viability and characteristics when increasing the prebiotic index. Different bacterial strains have different compatibility with prebiotics [113].
| Foodstuffs | Modification techniques | Probiotic bacteria | Prebiotic index | References |
|---|---|---|---|---|
| Corn flour | Acid hydrolysis | Lactobacillus plantarum IIA-1A5 |
0.60 | [18] |
| Corn flour | Annealing | Lactobacillus plantarum IIA-1A5 |
-0.03 | [18] |
| Corn flour | Debranching pullulanase | Lactobacillus plantarum IIA-1A5 |
0.48 | [18] |
| Corn flour | Microwave | Lactobacillus plantarum IIA-1A5 |
-0.06 | [18] |
| Daluga flour | HMT | Lactobacillus plantarum BSL |
3.74 | [114] |
| Banana flour | Autoclaving-cooling 1 cycle | Lactobacillus acidophilus | 0.91 | [111] |
| Banana flour | Autoclaving-cooling 1 cycle | Lactobacillus plantarum sa28k | 0.94 | [111] |
| Banana flour | Autoclaving-cooling 1 cycle | Lactobacillus fermentum 2B4 | 0.92 | [111] |
| Yam flour | LAB fermentation followed by autoclaving-cooling 3 cycles | Lactobacillus acidophilus | 5.83 | [115] |
| Yam flour | LAB fermentation followed by autoclaving-cooling 3 cycles | Bifidobacterium breve | 6.7 | [115] |
| Taro flour | LAB fermentation followed by autoclaving-cooling 1 cycle | Lactobacillus plantarum | 1.23 | [26] |
| Taro flour | LAB fermentation followed by autoclaving-cooling 1 cycle | Lactobacillus acidophilus | 2.05 | [26] |
This can be found in the research of Setiarto et al. [26], where there was a difference in the prebiotic index value of modified taro flour between the probiotics used (Lactobacillus plantarum and Lactobacillus acidophilus) (Table 10). The prebiotic effect and index can be increased by isolating RS from taro flour. The low prebiotic index in corn flour may be due to the absence of RS isolation treatment, so other components (non-RS starch) may affect the prebiotic index value. Purnamasari et al. [114] conducted RS isolation treatment on daluga flour, which was proven to have a relatively high prebiotic index.
RS has garnered significant attention due to its potential health benefits and diverse applications in food and nutrition. Its unique ability to resist digestion in the small intestine and ferment in the large intestine presents a myriad of promising prospects for the future [90]. Despite the challenges that need to be addressed for wider adoption and more effective use, the potential of RS is bright [91]. RS promotes the growth of beneficial gut bacteria by producing short-chain fatty acids (SCFAs), especially butyrate, which is crucial for colon health and reducing inflammation [92]. It may aid in weight loss by increasing feelings of fullness (satiety) and reducing the number of calories absorbed from food.
RS plays a significant role in improving insulin sensitivity and lowering postprandial (after-meal) blood glucose levels, which is beneficial for managing Type 2 diabetes [101]. By altering lipid metabolism, RS has shown potential in reducing cholesterol levels, contributing to heart health [102]. With the increasing demand for functional foods that offer health benefits, RS can be incorporated into a variety of products, including baked goods, snacks, and beverages. RS aligns with the trend towards clean labels, as it is naturally sourced from foods like potatoes, bananas, and grains. This makes it appealing to health-conscious consumers. RS has the potential to improve the texture and nutritional profile of gluten-free products, offering a better alternative for consumers with gluten sensitivities. It can be marketed as a natural prebiotic in the growing gut-health-focused product segment. RS is derived from renewable sources like grains, legumes, and tubers. As sustainable agriculture becomes more important, the cultivation of RS-rich crops could support environmentally-friendly food systems. Some resistant starch can be sourced from agricultural by-products, helping reduce food waste and creating a circular food economy.
There are five types of RS (RS1–RS5), each with distinct sources and properties. This variability poses a challenge for product formulation and consumer understanding. More research is needed to standardize the functional benefits of different types. While RS has well-documented health benefits, general consumer awareness remains low. Education campaigns will be crucial to increase its mainstream adoption. RS content can decrease during food processing, particularly with heat. For example, in baked goods or heated products, the structure of RS can change, reducing its health benefits. Optimizing food processing techniques to retain RS is a challenge that needs to be addressed. Efficiently producing and extracting RS at scale without losing its beneficial properties is a technical challenge. Large-scale industrial extraction methods can be costly and might affect the starch’s functionality. Regulatory frameworks around RS as a functional ingredient in various countries differ, especially when considering health claims. Securing global regulatory approvals and establishing clear guidelines will be key for the international market. While RS benefits gut health for many, some people may experience bloating or gastrointestinal discomfort when consuming higher amounts, which can limit its use in some populations. RS holds significant promise for improving health outcomes, enhancing food products, and supporting sustainable food systems. However, to unlock its full potential, challenges related to consumer awareness, regulatory approvals, food processing, and large-scale production need to be addressed. Continued research and development in this field will be essential to overcome these barriers and capitalize on the growing interest in gut health and functional foods.
RS from high-carbohydrate foods can be increased through several modification technologies. The study's results prove that physical, chemical, enzymatic, and LAB fermentation modification technologies can potentially increase RS levels in high-carbohydrate foods as a source of prebiotics. RS has the potential to be a sustainable alternative source of prebiotics, which can be proven through changes in the viability of gut microbiota groups and prebiotic index. Prebiotics as substrates in colonic fermentation have an important role in health by forming SCFA metabolites that have important bioactivities in human health. Alternative strategies that are effective, economical, efficient, and eco-friendly in modification technology are needed for sustainability in the production of RS. Physical modification technically has a simple process but requires high energy and production costs. Chemical modification requires chemicals in the process, which can cause environmental problems caused by strong acid waste such as HCl. Enzymatic modification is environmentally friendly, but the availability of debranching pullulanase is limited and expensive. LAB fermentation modification is technically easy to apply. Still, the tendency to increase RS content is very low due to the continued degradation of short-chain amylose in reducing sugars. The combination of LAB fermentation and physical modification, such as autoclaving-cooling, can minimize the use of high energy by reducing the number of AC cycles while being environmentally friendly and effective in increasing RS. Fermentation modification combined with autoclaving-cooling can be one of the sustainable modification technologies used to increase RS content in food ingredients.
All authors had equal contributions as the main contributors to this manuscript paper.
