Microgels are defined as discrete gel particles with sizes ranging from several micrometers to tens of micrometers. Although they are recognized as an impurity that appears during polymer synthesis, microgels have attracted attention mainly as a rheology control agent for paints. However, they are also expected to be used as a texture modifier in the field of food science. Specifically, they can be used as a fat analogue in processed foods. In this review, based on their classification, research examples of the different methods used for producing microgels are given. Moreover, as an example, a study on agar microgels obtained by applying an emulsifying system to low-oil mayonnaise is described in detail.
This article reviews the research progress of non-thermal disinfection technologies in food and introduces the principles of non-thermal disinfection technologies such as ultra-high pressure, ozone, acid electrolyzed water, irradiation, magnetic sterilization, high-pressure carbon dioxide, and natural antibacterial. We discuss the characteristics and application progress of non-thermal disinfection technologies in food processing and analyze their development trend based on their application and promotion in food processing and storage.
Due to its highly perishable nature, fresh Chinese winter jujube fruit is preserved, commonly by drying. In this study, dewatering of fresh Chinese winter jujube was carried out by subcritical dimethyl ether (DME). Additionally, wax was simultaneously extracted from the fruit during the dewatering process. The maximum dehydration efficiency was 93.33 ± 0.34% when the dewatering experiment was conducted at 55 °C with 8 cycles. The content of total soluble solids, total sugars, and total flavonoids of dried jujube fruit (JD) by subcritical DME dewatering was somewhat lower than those in the freeze-dried jujube fruit (JF). However, the content of total phenols and VC in JD was close to those in JF, and the protein content in JD was higher than that in JF. The extracted wax primarily comprised acids, the most abundant of which was hexadecanoic acid. It had melting points of 53.71 °C–54.62 °C. The study demonstrates that subcritical DME can be used to dry Chinese winter jujube fruit. There is a small loss of nutritional content, but the speed, economy, and environmental friendliness of the process are advantages compared to other methods. Results further suggest that jujube wax has potential for use in the cosmetic and food industries.
The aqueous extract of Rhizopus oryzae U-1 (RU) increases the number of Th1 cells, which defend against Salmonella infection and regulate immunity in rats. In this study, we demonstrated the anti-dermatitis effects of RU in a picryl chloride (PiCl)-induced mouse model of atopic dermatitis. RU treatment significantly decreased the time-dependent exacerbation of dermatitis scores and increased the final body weight and food intake. A significant decrease in serum IgE and IL-4 levels confirmed that RU treatment suppressed the exacerbation of atopic dermatitis. Flow cytometric analysis revealed that RU treatment significantly increased CD4+ IFN-γ+ (Th1) and decreased CD4+ IL-4+ (IL-4+ Th) cell numbers. Thus, the oral administration of RU effectively suppressed atopic dermatitis induced by PiCl, and the decrease in the number of CD4+ IL-4+ cells and serum IL-4 levels may be partially mediated by RU in mice.
Abstract: Cyclodextrins (CDs) are widely applied to improve the aqueous solubility and stability of nutraceuticals with the advantages of high safety and low cost. In this study, the binding capacities of CDs (α-CD, β-CD, maltosyl-β-CD, hydroxypropyl-β-CD and γ-CD) with mangiferin were compared by the phase solubility method and isothermal titration calorimetry. γ-CD could completely encapsulate mangiferin at the molar ratio of 1:1, which coincided with the molecular docking and ONIOM calculation results that γ-CD had the lowest interaction energy with mangiferin. The independent gradient model (IGM) visualized the intermolecular non-covalent binding and electrostatic potential around mangiferin during interaction. By complexing with γ-CD, mangiferin was molecularly dispersed in the matrix of γ-CD with its aromatic ring in the hydrophobic cavity. Compared with pure mangiferin, the mangiferin/γ-CD complex exhibited the stronger chemical antioxidant activities. The obtained result can promote the application of mangiferin and γ-CD in foods.
Maillard reaction products (MRPs) produced during thermal processing and storage of foods have received considerable attention because of their potential antioxidant activity. We investigated whether heat-dried tomato (Solanum lycopersicum L.) extracts and their MRPs confer longevity and neuroprotective effects in Caenorhabditis elegans. Heat-drying of mature green tomato resulted in increased absorbance at 294 nm and 420 nm, which indicated the presence of MRPs. Heat-dried green tomato extract and its MRP fraction exhibited DPPH and ABTS radical scavenging activities and significantly extended the lifespan of C. elegans. The MRP fraction protected against β-amyloid-, 1-methyl-4-phenylpyridinium (MPP+)-, and H2O2-induced neurotoxicity in C. elegans. These results suggest that the dry processing of unripe green tomato induces MRP formation that might protect against neurodegeneration.
Lactic acid bacteria (LAB) are known to promote deterioration of quality in meat products, such as discoloration and slime production. In this study, five types of liquid smoke, considered food additives, were assayed for potential anti-spoilage LABs from meat products. The spoilage LABs isolated from meat products were identified as Lactobacillus plantarum, Enterococcus malodoratus, Streptococcus thermophilus, or Carnobacterium maltaromaticum. The liquid smoke product (LS1), made from mixed wood, was more effective in terms of spoilage LAB isolate activities. It had the highest phenol content along with the most varied component among the tested products. In the model sausages containing 0.5% LS1, which was incubated at 30 °C for 5 d for accelerating their deterioration, the enumeration of LAB and staphylococci was significantly lower than that of the control. Therefore, LS1 was suggested to be useful for suppressing not only LAB but also the other bacteria related to spoilage of meat products.
Here, the changes in phenolic composition and antioxidant activities (ABTS, DPPH, and FRAP) of raw and pickled cowpea green pod during in vitro simulated gastrointestinal digestion (GID) were investigated. The inhibitory activities of the undigested and digested samples towards α-amylase, α-glucosidase and lipase were determined. Results revealed that total phenolic (TP) and flavonoid (TF) contents of both raw and pickled samples were increased after gastric and intestinal digestion, and the pickled sample had lower TP and TF content after each digestion phase. A similar trend was observed for antioxidant activities, which were significantly correlated with TP and TF contents (p < 0.05). Seven phenolic compounds were identified and quantified by HPLC-DAD. Their contents were affected by digestion and pickling, and raw cowpea pod had higher contents before and after GID. Inhibitory effects towards α-amylase, α-glucosidase and lipase were increased for raw cowpea pod after GID. Pickled cowpea pod also showed an increased inhibitory activity towards lipase, while no activity towards α-amylase and α-glucosidase. Raw cowpea pod had higher inhibitory effects towards α-amylase, α-glucosidase and lipase than the pickled one at each digestion phase. Our results showed that pickling process reduced the health-promoting properties of cowpea green pod.
White bamboo is the swollen stem of Zizania latifolia parasitized by the smut fungus Ustilago esculenta. Five samples of galls were harvested at different stages of swelling, along with young seedlings of Z. latifolia and isolated colonies of U. esculenta. The inhibition capacity of boiling water or 50% ethanol extracts on NO release by RAW264 cells, which was stimulated with lipopolysaccharide, was evaluated as anti-inflammatory activity, while the NO induction capacity was evaluated as immunostimulatory activity. Total polyphenol (TPP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity were also measured. The anti-inflammatory effect, as well as TPP and DPPH, was comprehensively detected in the ethanol extracts. The immunostimulating activity was observed in the boiled extracts at different levels, depending on the swelling stage, and was especially high in the top (apical) part. These data may indicate that functional components could be dynamically induced by interactions between Z. latifolia and U. esculenta.
The effects of three phytosterols (β-sitosterol, stigmasterol, and campesterol) on the formation of 3-monochloropropane-1,2-diol (3-MCPD) esters and the possible mechanism were investigated in this study. Model reaction with 1,2-dipalmitoyl-sn-glycerol (DPG) and sodium chloride as the reacting precursors was adopted to investigate effects of three phytosterols on the formation of 3-MCPD esters. The results showed that three phytosterols exhibited inhibiting activity on the formation of 3-MCPD esters in the model reactions. ESR signal detection indicated that the phytosterols suppressed the formation of free radical in the model reactions. In addtion, 3-chloro-Δ5-cholestenes were detected in the reaction models by using UPLC-APCI-MS. It suggested that phytosterols reacted with chloride and transformed to 3-chloro-Δ5-cholestenes. Therefore, the possible mechanism of phytosterols inhibiting the formation of 3-MCPD esters could be proposed that phytosterols suppressed formation of free radical intermediates in model reactions and competed with DPG for chloride ion to reduce the formation of 3-MCPD esters.
The inhibition of the β-glucuronidase activity of the intestinal microbiota could contribute to reducing the risk of colon cancer. This study aimed to investigate the effect of alkyl catechols, which are found in fermented foods and wood smoke utilized in food preservation, on β-glucuronidase activity. In this regard, 65.5% inhibition of β-glucuronidase activity was demonstrated by 4-ethylcatechol (4EC) at 20 µM. The concentration of 4EC, which led to 50% loss of the enzyme activity was 7.57 µM. In addition, a kinetic study was conducted on β-glucuronidase inhibition by 4EC through Lineweaver-Burk analysis and the kinetic profile proposed that 4EC is a competitive inhibitor of β-glucuronidase. Analysis of the structure-activity relationship revealed the importance of the ethyl moiety and catechol structure of 4EC for the β-glucuronidase inhibitory activity.
Insect feces tea has been used as traditional Chinese medicine. Obesity is one of the main factors of lifestyle diseases, so prevention and improvement of obesity are indispensable for living a healthy life in modern society. We examined the lipid accumulation-suppressing effect of tea from Locusta migratoria (LT) in vitro and in vivo assays. LT suppressed the differentiation of 3T3-L1 cells to adipocytes, but not the process of accumulation of lipid droplets. Furthermore, it suppressed the expression of peroxisome proliferator-activated receptor (PPAR)γ and CCAAT/enhancer-binding protein (C/EBP)α, master regulators of differentiation. In mice fed a high-fat diet and administered with LT, the body weight did not change compared to the mice fed with water; however, the white fat weight, particularly the visceral fat, was reduced significantly. These results indicated the potential of LT to suppress fat accumulation by inhibiting adipocyte differentiation.