Technical paper
Instrumental Analysis of Texture, Color and Acceptance of Instant Dessert Formulated with Broken-rice Grains
2014 年 20 巻 4 号 p. 785-792
詳細
2014 年 20 巻 4 号 p. 785-792
This study aimed to determine the color and texture profile of instant desserts produced from mixtures of pregelatinized flour of broken-rice grains, milk powder and sugar. A simplex design with seven different formulations of instant dessert and two replicates at the central point was used. Proximate composition, microbiological safety and acceptance of dessert selected (with greater desirability) were also determined. The texture attributes are changed depending on the amount of pregelatinized flour, milk powder and sugar used, in this way, different formulations can be used according to each texture desired. The ideal formulation of white chocolate instant dessert consisted of 39.6 g (100 g)−1 pregelatinized flour, 25.5 g (100 g)−1 sugar, 22.8 g (100 g)−1 milk powder, 10 g (100 g)−1 flavor and 2 g (100 g)−1 gum. The instant dessert with pregelatinized rice flour presents textural, nutritional, microbiological and sensory characteristics satisfactory, and is a good alternative to commercial instant desserts based on modified corn starch.
In Brazil, rice is consumed preferably in the form of polished white grains obtained by the conventional process of industrialization (Helbig et al., 2007). During the processing of rice grains, husk, bran and broken grains are generated as by-products. Variations of moisture at harvest, improper artificial drying and thermal variations can result in the breakage of these grains (Smiderle and Pereira, 2008).
Rice flour obtained by milling broken grains imparts functional characteristics to products and formulations that use it. However, rice flour is underexplored, despite its benefits, such as little pronounced flavor, which does not interfere with the flavor of most foods, and non-allergenic characteristics (Dors et al., 2006). Meantime, rice flour has technological limitations related to its native starch. For this reason some technologies have been used for changing its physical, chemical and sensory parameters, in order to obtain different characteristics.
Thermoplastic extrusion has been a good alternative, because this process causes protein denaturation, homogenization, starch gelatinization, liquefaction of fat, and expansion of the processed material, among others. The starch or starch flour when pregelatinized undergoes chemical changes that cause swelling and rupture of the granules, modification of crystalline structures, which increase the solubility and viscosity in cold water (Lustosa et al., 2009; Tavares, 2010; Trombini and Leonel, 2010).
One potential application for pregelatinized flour of broken-rice grain is the production of instant food, much appreciated for their practicality and convenience. The instant foods are usually in powder form and easily miscible in water, and not require heat to achieve the desired texture (Vissoto et al., 2006). Good rheological properties have been attributed to foods with the addition of starch pastes, especially modified starches, but little was reported on modified flour.
Sensory analysis has been used for years to test texture attributes, but this takes time and turns out to be very costly, hence the use of instrumental methods, aiming to identify quality factors (Pajak et al., 2010). The main quality factors in food are the appearance (color, shape, size), flavor (including taste and odor), texture (tactile sensation) and nutritional value. The ISO standards define the texture as the set of mechanical, geometric and surface properties of a product perceived by the seven mechanical, tactile, and in some cases visual and auditory receptors (Damásio et al., 1999).
Because the price of corn starch is about 2.5 times larger than that of broken-rice grains, the aim of this study was to investigate the feasibility of substitution of pregelatinezed corn starch in the production of instant desserts by a by-product of rice. The textural profile and instrumental parameters of color of instant desserts were examined according to the concentration pregelatinized flour of broken-rice grains (PGRF), milk powder and sugar, to select the formulation more convenient, considering its similarity to a commercial product formulated with pregelatinized corn starch. In addition to proximate composition, microbiological hazard, and sensory acceptance of instant dessert selected.
For development of experimental instant desserts were used as raw materials: whole milk powder (Itambé®), icing sugar (União®), white chocolate artificial flavor and guar gum (Pro-Sorvete®), which were acquired in the local trade of Goiânia. Broken-rice grains were provided by the company Cristal Alimentos Ltda®, located in the city of Aparecida de Goiânia, state of Goiás, Brazil.
Production of pregelatinized flour of broken-rice grains For the production of pregelatinized flour, broken-rice grains of cultivar IRGA-417 were extruded in a single screw thermoplastic extruder (Imbramaq, PQ-30, Ribeirão Preto, Brazil) with screw compression ratio of 3:1, feed rate of 350 g min−1, circular die opening of 4 mm in diameter, temperature at the first, second and third heating zones of the extruder of 35°C, 50°C and 90°C, respectively, and screw speed of 250 rpm. Later, the moisture conditioning process ensured that the final moisture content was 18 g (100 g)−1 on a wet basis (wb). After conditioning the moisture for 24 hours, the sample was removed from the cold chamber and maintained at room temperature until the beginning of the extrusion process. The extrudates were ground in a knife mill (Perten Laboratory Mill, 3100, Kungens Kurva, Sweden) with 24-mesh sieve, constituting the pregelatinized flour of broken-rice grains (PGRF).
Characterization of the broken-rice grains and the pregelatinized flour The broken-rice grains and PGRF was subjected to particle size analysis (AOAC, 2010). The contents of lipids and protein of PGRF were evaluated according to the methods recommended by AOAC (2010). The PGRF and broken-rice grains also were evaluated as for water absorption index (WAI) and water solubility index (WSI) according to the method of Anderson et al. (1969).
Preparation of instant desserts The proportions of major ingredients (PGRF, milk powder and sugar), and its values in pseudocomponents (Table 1) were defined by preliminary tests, following a mixture design (Box et al., 1978). The proportion of fixed ingredients, guar gum and white chocolate artificial flavor have been determined in preliminary tests and amounted to 2 and 10 g (100 g)−1 formulations, respectively. All ingredients (guar gum, PGRF, milk powder, sugar and artificial flavor) were weighed and mixed manually. They were then placed in a household blender (Mondial Premium, L-51, Goiânia, Brasil) with 1.6 L of capacity (simulating the form of preparation by the consumer) with the addition of 300 mL of cold water (10°C) and liquefied for 5 minutes, until homogeneous. The mixture was divided into 30 mL portions in beakers with a capacity of 50 mL. These were taken to the refrigerator at 5 ± 1°C for 24 hours, comprising the experimental instant desserts.
| Formulation | Pseudocomponent* | Proportion of ingredients | ||||
|---|---|---|---|---|---|---|
| PGRF | Milk | Sugar | PGRF (x1) | Milk (x2) | Sugar(x3) | |
| 1 | 0.6667 | 0.0000 | 0.3333 | 0.55 | 0.10 | 0.35 |
| 6 | 0.0000 | 0.3333 | 0.6667 | 0.35 | 0.20 | 0.45 |
| 7(1)1 | 0.3333 | 0.3333 | 0.3333 | 0.45 | 0.20 | 0.35 |
| 7(2) | 0.3333 | 0.3333 | 0.3333 | 0.45 | 0.20 | 0.35 |
| 7(3) | 0.3333 | 0.3333 | 0.3333 | 0.45 | 0.20 | 0.35 |
| 4 | 0.3333 | 0.6667 | 0.0000 | 0.45 | 0.30 | 0.25 |
| 3 | 0.6667 | 0.3333 | 0.0000 | 0.55 | 0.20 | 0.25 |
| 5 | 0.3333 | 0.0000 | 0.6667 | 0.45 | 0.10 | 0.45 |
| 2 | 0.0000 | 0.6667 | 0.3333 | 0.35 | 0.30 | 0.35 |
Texture profile For the instrumental analysis of the texture profile we used texturometer TA.XT (Extralab, Express Enhanced, Godalming, UK) and the recording of results was obtained through the Software Express Texture (Extralab, Express Enhanced, Godalming, UK). The operating conditions proposed by Lobato et al. (2012) were used, standardized as: load of 0.05 N, cylindrical specimen of P-20 stainless steel (diameter of 20 mm) with penetration depth of 5 mm, penetration speed 2 mm s−1 in two cycles penetration. Analyses were carried out in ten replicates. The instant dessert samples were placed in plastic containers (diameter of 50 mm and height of 55 mm), and tested 24 hours after preparation, observing the maintenance of temperature (10°C). The parameters of hardness (force necessary to attain a given deformation — N), cohesiveness (extent to which a material can be deformed before it ruptures — dimensionless), springiness (rate at which a deformed material goes back to its undeformed condition after the deforming force is removed — dimensionless), adhesiveness (work necessary to overcome the attractive forces between the surface of the food and the surface of the other materials with which the food comes in contact — N m) and gumminess (relate to degree of disintegrate a semi-solid food to a state ready for swallowing and is the product of hardness and cohesiveness — N) were measured (Szczesniak, 2002). We used the same methodology for determining the textural profile of a sample of commercial instant dessert formulated with modified corn starch, traditional in market.
Instrumental analysis of color It was used a Hunter Lab colorimeter (Color Quest II, Reston, USA) to obtain instrumental color measurements (L*, a* and b*) using the CIE (Commission Internationale de L'Eclairage). All analyses of texture and color were performed in 10 replicates.
Statistical analysis, desirability test and validation of models Polynomial models were fitted to each response of texture obtained by estimating the respective coefficients through the Scheffe canonical models for three components: linear and quadratic models. Fitted mathematical models were subjected to analysis of variance (Anova) to assess the significance level of the effect of the concentration of each component of the mixture over each response, the adjusted coefficient of determination (R2adj) and the lack of fit. For obtaining the experimental design, data analysis and construction of graphs we used the software Statistica 7.0 (Statsoft, 2004). To define the values of the desirability for the texture it was used the instrumental textural parameters of standard commercial dessert. For luminosity, it was desired to enhance the white color, matching the flavor chosen (white chocolate), exempting the addition of dyes, and for this it was not used any standard dessert, only the standard white of the equipment. We conducted a new test for validation of the models with the formulation of greater desirability, and compared the results with those observed, using two original replicates and five replicates.
Proximate composition, microbiological evaluation and acceptance testing of selected formulation The contents of moisture, ash, fat and protein of the selected instant dessert and were evaluated according to the methods recommended by AOAC (2010), and carbohydrates were estimated by difference. Counts of Bacillus cereus, total coliform, thermotolerant coliform, molds and yeasts, coagulase-positive Staphylococcus, as well as the detection of presence/absence of Salmonellasp in the most desirable instant dessert sample were performed according to the techniques described by the American Public Health Association (APHA, 2001). We evaluated the attributes taste, texture and overall assessment using a nine point-hedonic scale (9 - like extremely, 5 - neither like nor dislike and 1 - extremely dislike), and purchase intent. We used a randomized block design (Stone and Sidel, 1993). The product was considered accepted when scored higher than 6. We recruited 50 adult consumers, of both sexes, according to the interest in participating in the research. The test was performed in a sensory analysis laboratory, and the sample was tasted in individual booths under white light. This research project was approved by the Ethics Committee of the Federal University of Goiás, protocol 363/2011.
Characterization of the broken-rice grains and the pregelatinized flour The broken grains of rice were mostly retained by the sieves of 16 and 12-mesh, with the total of 99.16 g (100 g)−1. The remaining was retained by the sieves of 9 and 24-mesh. The use of broken grains with particle size much larger than the rice flour traditionally used in extrusion, facilitated feeding the extruder, saving time and energy required in grinding. With respect to pregelatinized flour of broken-rice grains (PGRF), greater retention [53.15 g (100 g)−1] was obtained in the 100-mesh sieve, a value close to that found by Dors et al. (2006) who characterized pregelatinized flour of rice flour to produce a dessert, whose greater retention [76.99 g (100 g)−1] was in the sieve of 115-mesh (0.125 mm). It is worth noting that the flour with smaller particles will probably result in a higher quality dessert regarding the texture, because it will possess larger contact surface for water absorption (Silva et al., 2009).
The PGRF presented 5.84 g (100 g)−1 of protein and 0.38 g (100 g)−1 of lipids. Becker et al. (2013) obtained for the PGRF (cultivar IRGA-417) a protein content of 8.54 g (100 g)−1 and 0.24 g (100 g)−1 of lipids, probably attributed to differences in extrusion conditions used in flours preparation. These same authors reported an amylose content of PGRF 27.24 g (100 g)−1, so this genotype may be classified as intermediate amylose.
The WAI and WSI obtained in broken-rice were 2.02 ggel (gdry matter)−1 and 1.21 g (100 g)−1, respectively, while in PGRF were 7.48 ggel (gdry matter)−1 and 24.89 g (100 g)−1. Limberger et al. (2006) reported higher values of WAI and WSI in PGRF, 14.03 ggel (gdry matter)−1 and 35.91 g (100 g)−1, respectively, while Doors et al. (2006) minor values, 4.58 ggel (gdry matter)−1 and 9.49 g (100 g)−1. Therefore, this work yielded intermediate values of WAI and WSI. WAI is related to the availability of the hydrophilic groups (-OH) to bind with water molecules and a gel-forming ability of the molecules. Thus, only those starch granules that have undergone the process of gelatinization are capable of absorbing water and swelling at room temperature. The WSI is used to measure the degradation of starch, and its increase indicates an increase in the number of fragmented molecules soluble in water (Ding et al., 2005). Gelatinization is defined as the collapse of the granular sorting, during which irreversible changes occur in the properties, such as swelling of the granules, crystalline melting, loss of birefringence, the disruption of the granules to release amylose and increase the viscosity of this suspension (Thiré et al., 2003). According to the values of WAI and WSI obtained in broken-rice grains and PGRF, can be deduced indirectly happened gelatinization in PGRF.
Guar gum is a hydrocolloid produced from the seed endosperm of Cyamopsis tetragonolobus, is highly viscous at low concentrations and has useful thickening, stabilizing and water binding properties. It is also used to improve mixing tolerance, to prolong the shelf-life of the end product through its moisture retention property and to prevent syneresis in frozen food products (Mandala, 2005; Ruperez and Bravo, 2001). On the other hand, food hydrocolloids control the gelatinization and retrogradation behavior of starch (Funami et al., 2005). Thus, rice starch and guar gum are used together in many types of food in order to improve their stability and texture (Kadan et al., 2000). However, physical modification using extrusion cooking is an alternative way to improve the properties of native starches or rice flour, and also to ameliorate negative features due to starch retrogradation on storage of starch-food products (Hagenimana et al., 2006). Pre-gelatinized starch is capable of instantly forming numerous hydrogen bonds with water (Onyango et al., 2010). Extrusion cooking of rice flour can result in the enhancement of functional properties like water absorption, water solubility, rheological behavior of dough (Grenos et al., 1993). Guar gum and rice starch resulted in gels with decreased elasticity and lower resistance to deformation, likely indicating strong interactions between galactomannan structure and the starch molecules (Kim and Yoo, 2006). In this study, the resulting hydrogen bonds by extrusion cooking, the protein and amylose derived from rice flour, and the water binding property of guar gum led to the formation of strong gels.
Texture profile and color From the instrumental data of texture and color and from analysis of variance, we fitted polynomial mathematical models, and determined the significance level (P), the lack of fit (LF) and the coefficients of determination (R2) for the parameters of texture and color of the instant desserts prepared with PGRF, milk powder and sugar (Table 2).
| Attribute | Model | LF | P | R2 |
|---|---|---|---|---|
| Hardness | y1 = 62.35x1 + 24.18x2 + 8.16x3 − 39.13x1x2 − 27.93x1x3 | 0.36 | 0.002 | 0.94 |
| Gumminess | y2 = 39.30x1 + 11.37x2 + 2.86x3 − 21.16x1x2 − 15.84x1x3 − 13.87x2x3 | 0.37 | 0.006 | 0.96 |
| Adhesiveness | y3 = −2,62x1 − 4.95x2 + 3.28x3 − 17.21x1x2 − 20.00x1x3 − 28.64x2x3 | 0.84 | 0.013 | 0.93 |
| L* | y4 = 75.06x1 + 82.34x2 + 93.58x3 + 37.17x1x2 − 24.21x2x3 | 0.01 | 0.04 | 0.87 |
| b* | y5 = 0.29x1 + 1.80x2 + 3.45x3 + 6.62x1x2 − 6.12x2x3 | 0.01 | 0.03 | 0.95 |
The correlation coefficients of significant models ranged between 0.86 and 0.96 and the lack of fit was only significant for L* and b*. Waszczynskyj et al. (1981) suggest that in analysis of variance, whenever the pure error mean square assumes very low values compared to the total error, the significant lack of fit should be considered irrelevant, as is the case of L* and b* in the present work. The polynomial models for attributes hardness, gumminess, adhesiveness and L* and b* were significant, but not for springiness, cohesiveness and a*. The springiness of the experimental instant desserts was low, and ranged only 3.2%, between 0.93 (midpoint) and 0.96 (formulations 1, 5 and 6). The cohesiveness also was low, between 0.59 (formulation 4) and 0.64 (formulation 6). Therefore, concentrations of PGRF, milk powder and sugar did not affect these parameters of instrumental texture. A tendency to higher hardness was observed the higher the amount of PGRF and the lower the amount of sugar and milk powder (Fig. 1A).
Response surfaces generated from experimental models (in terms of pseudocomponents) the textural properties of the gels: (A) Hardness, (B) gumminess and (C) adhesiveness. The demarcated area between dots 1 and 6 shows experimentally analyzed region.
The hardness of the gels can be attributed to the characteristics of starch, such as retrogradation, in which there is the associations between molecules, directly influencing the texture. Gels with higher rigidity generally have higher amylose content, thus giving a firm consistency to the product. Soft, firm and hard are popular terms to describe the hardness (Szczesniak, 2002). Some properties of these gels depend on factors such as the percentage of gelatinized granules, the interaction between the dispersed and continuous phases of the gel and characteristics of the amylose matrix (Choi and Kerr, 2003; Sandhu and Singh, 2007).
The quantity of PGRF and milk powder showed different tendencies, with increased amount of the first ingredient and with reduced of the second, it was obtained the highest values for gumminess (Fig. 1B). Although sugar has not significantly affected this attribute alone, the higher the concentration of this substance and less flour (interaction x1x3), the lower the values of gumminess. Due to the soft extrusion process, the PGRF has a portion of still intact starch granules. These granules collaborate to the structure of the gel network formed, not excluding the role of adding 2 g (100 g)−1 guar gum. Zavareze et al. (2010), working with textural profile of rice starch gels subjected to temperatures of 55°C obtained hardness values of 34.77 N and gumminess of 27.06 N; measures that corroborate with values of hardness and gumminess of this work. It should be emphasized that these attributes varied according to the amount of starch in the formulation. The use of temperature can lead the starch to a previous partial or complete gelatinization, depending on the processing parameters used for starch modification, which gives specific textural characteristics, which can directly influence components like firmness and cohesion of the gels formed.
The greater the amount of sugar, the lower the adhesiveness, with tendency to positive values (Fig. 1C). This trend of zero or positive adhesiveness was observed, as increased the amount of sugar and decreased of other ingredients, presenting less resistance to the detachment from the texturometer probe. The interactions between the three ingredients were significant, indicating that the adhesiveness was influenced by the reactions between the components of PGRF, milk and sugar, with the highest values achieved with PGRF concentrations ranging between 35 and 52 g (100 g)−1, milk between 10 and 30 g (100 g)−1, and sugar between 25 and 45 g (100 g)−1. In experimental instant desserts, milk powder had significant influence on the adhesiveness, probably due to lipid supply that provides consistency and body and to the action of the proteins in its composition which have functional advantage to increase the viscosity due to their ability to retain water and form gels. The presence of casein assists in the formation of the protein gel, providing body and texture (Santos et al., 2008).
Lobato et al. (2012) examined the textural properties of puddings with native corn starch, milk and inulin, and registered values of hardness between 0.16 and 1.18 N, gumminess between 0.10 and 0.50 N and adhesiveness between 0.02 and 0.13 N m. In the present work, we verified values of hardness between 10 and 40 N, between 5 and 35 N for gumminess, and negative values for adhesiveness. This difference of hardness and gumminess is because the formulation of the instant desserts used a greater amount of previously pregelatinized starch, which provided textural and rheological characteristics very different from the products investigated by the above author.
The color of food, including instant desserts, is one of the quality factors most observed by consumers, being an important sensory characteristic for commercialization. The values of chroma a* varied little between −2.09 (formulation 6) and −1.59 (formulation 5), reaching near zero (pure white), so do not even tended to green or to red. For the luminosity, the effect of the interactions between PGRF and milk and between sugar and milk was significant.
For chroma b*, the interactions between PGRF and milk (x1x2) and between milk and sugar (x2x3) were significant.Contour lines graphs drawn from models fitted for L* and chroma b* of instant desserts are presented in Fig. 2A and 2B. There was a trend for higher luminosity (values above 88) with greater amount of sugar (area outlined by the dots 5, A and B in the figure 2A). In intermediate amounts of milk and PGRF and sugar it was obtained intermediate luminosity, represented by the dot 7.
(A) Luminosity and (B) chroma b* depending on the proportions of pre-gelatinized broken-rice flour, milk and sugar, in pseudocomponents. The demarcated area between dots 1 and 6 shows experimentally analyzed region.
The maximum amount of PGRF with small amounts of sugar and milk reduced the luminosity, probably because the PGRF is darker than the other ingredients.
Therefore, we observed the highest luminosity values in intermediate amounts of PGRF [41 to 46 g (100 g)−1], low proportions of milk [10 to 14 g (100 g)−1] and high proportions of sugar [44 to 45 g (100 g)−1]. Nevertheless, the area with minimal amounts of PGRF and larger amounts of milk also showed a tendency to reduced luminosity, probably due to the pigments present in milk. A greater presence of sugar also results in higher luminosity because the glassy surface of the sugar crystals can reflect light. The formulations showed values between −2.0 and −1.5 (33.3% variation) in relation to the coordinate a*, with a trend of values close to neutrality in all desserts. Browning products and milk powder pigments resulting from the Maillard reaction were not enough to modify this coordinate. A trend to low chroma b* was observed as lower the amount of milk and sugar and higher amount of PGRF in samples of instant dessert, tending to less yellowish samples (Fig. 2B). Lower values of chroma b* (1 to 1.5) were obtained with maximum amount of PGRF, and minimum amount of milk and sugar, in the area of the graph formed by the dots S, R and 1 (Fig. 2B). This is probably due to the lower smaller amount of milk, which implies a lower concentration of fat-soluble compounds such as carotene and riboflavin, which give such color.
Low concentrations of PGRF combined with the interaction between milk and sugar also tend to produce desserts with low values of b*, in other words, less yellowish.
The more neutral instant desserts, near the zero value of b*, were obtained with 35 – 38 g (100 g)−1 PGRF, 20 – 30 g (100 g)−1 milk powder, and 32 – 45 g (100 g)−1 sugar. The presence of whole milk powder also justifies the yellowish shades, although dilution reduces this chromaticity during addition of water to the formulation, probably due to the presence of casein in the form of colloidal dispersion forming particles of varying size. These particles scatter light and give milk its characteristic white color, and are called micelles. The milk powder during the manufacturing process undergoes Maillard reaction. Hydroxymethylfurfural (HMF) is formed during this reaction, and is originally a dark brown pigment (Stapelfeldt et al., 1997).
Vidigal (2009) studied sensory characteristics of diet dessert with corn starch, and obtained 80.2 of luminosity, value similar to the observed in this work. This same author has verified values of −3.4 and 8.69 for coordinates a* and b* respectively, obtaining a dessert with no red color (near the neutral), and more yellowish than the experimental dessert of the present study, probably due to carotenoids present in maize. The desirability test indicated the most desired mixture with 0.33:0.53:0.13 in pseudocomponents, or proportions of 45 g (100 g)−1 PGRF, 25 g (100 g)−1 milk powder and 28 g (100 g)−1 sugar.
Thus, the ideal formulation of white chocolate instant dessert consisted of 39.6 g (100 g)−1 PGRF, 25.5 g (100 g)−1 sugar, 22.8 g (100 g)−1 milk powder, 10 g (100 g)−1 flavor and 2 g (100 g)−1 gum. This was used to validate the significant models, with the aim of generating theoretical patterns with predictive purposes, for comparison and confirmation of the efficiency of the mixture, texturometer calibration and optimization reliability.
In this way, the validation of the models by comparing the results observed with the expected was conducted using the results of texture (hardness, gumminess and adhesiveness) and luminosity. Regarding the results of texture, the predicted model corroborated with the values found analytically, i.e., we obtained a powdered mixture for instant dessert, which after prepared, has textural characteristics close to those predicted by the models, with percentages of variation of 34.8% for adhesiveness, 6% for hardness, 7.7% for gumminess, and 1.2% for luminosity.
The differences between the values calculated and values obtained in the validation test are related to experimental errors and the coefficient of determination of equations. Thereby, the models can be considered predictive.
Proximate composition, microbiological evaluation and acceptance testing of selected formulation The proximate composition of the ideal mixture for instant dessert (powdered) indicated that it has a high nutritional value, consisted of 5.38 g (100 g)−1 moisture, 1.63 g (100 g)−1 ash, 9.59 g (100 g)−1 protein, 6.25 g (100 g)−1 total fat and 77.15 g (100 g)−1 carbohydrate. The product also meets the microbiological standards established by Resolution RDC 12 of the National Agency of Sanitary Surveillance of the Ministry of Health, from January 2nd, 2001, to flours and instant foods (Brasil, 2001). As pre-defined in methodology, the product would be considered accepted if obtained higher frequency of scores greater than or equal to 6 (like slightly). The dessert was accepted in all attributes. For flavor, 96% of scores were between 6 and 9, with scores 7 (like moderately) and 8 (like very much) the most obtained. Regarding texture and overall assessment, 92% of scores were above or equal to the cutoff defined, with the highest frequency for the score 8.
Therefore, the samples had an average of 36% acceptance for flavor, 32% for texture, and 33% for the overall attribute. Dors et al. (2006), when analyzed the acceptance of a dessert of modified rice starch, observed an average of 35% acceptance, corroborating our results. It can be claimed that 100% of the panelists demonstrated some type of purchase intent for the white chocolate instant dessert, and 20% actually buy the product.
The attributes of texture are changed depending on the amount of pregelatinized flour of broken-rice grains, milk powder and sugar used, in this way, different formulations can be used according to each texture desired. The ideal instant dessert formulation contains 39.6 g (100 g)−1 PGRF, 25.5 g (100 g)−1 sugar, 22.8 g (100 g)−1 milk powder, 10 g (100 g)−1 flavor and 2 g (100 g)−1 gum. Thus, it is possible to produce a dessert without the aid of heat, with instant and texture characteristics comparable to a similar commercial product based on modified corn starch. The powder mixture for instant dessert with pregelatinized rice flour presents textural, nutritional, microbiological and sensory characteristics satisfactory, and is a good alternative to commercial instant desserts based on modified corn starch. Therefore, it is feasible to use extruded flour of broken-rice grains in the preparation of instant dessert.
Acknowledgements To Capes for financial support and master scholarship, and to FAPEG for financial support.
