Velazquez, GonzaloMendez-Montealvo, Ma GuadalupeWelti-Chanes, JorgeRamirez, Jose Alberto...
7页
查看更多>>摘要：This study was carried out to evaluate the effect of high pressure processing (HPP) and thermal treatments on the gelling properties of proteins from blue crab meat. Crabmeat was pressurized at 100, 300, and 500 MPa (10 degrees C/5 min) with and without heating (90 degrees C/20 min) after the HPP treatment. Treated samples were analyzed by protein interactions, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and dynamic rheometry. Protein gelation after pressurization was based on physical interactions which were modified after HPP treatment; meanwhile, thermal gelation was based mainly on the formation of covalent bonds. DSC showed that pressure levels over 300 MPa reduced myosin denaturation temperature indicating protein unfolding. HPP treatment at 100 MPa led to a partial protein denaturation effect. FTIR results showed a reduction in the fraction of alpha-helix structure along with a development of beta-sheet portion as a result of protein denaturation promoted by the application of pressure. The sweep temperature analysis indicated that the combination of treatments stabilized the protein network in the gels from blue crab meat. The combination of pressure (100 MPa) and heat (90 degrees C) treatments allowed obtaining gels from crabmeat proteins with optimal rheological properties.
查看更多>>摘要：During the digestion of rice, proteins are among the main rice components and are hydrolyzed into amino acids by enzymes. In this study, we evaluated the influence of free amino acids liberated from rice proteins during digestion on rice starch digestibility for exploring the starch digestion mechanisms in the presence of rice protein. The results showed that all the amino acids inhibited the activity of porcine pancreatic alpha-amylase. Moreover, glutamate (Glu) displayed a mixed-type suppression of porcine pancreatic alpha-amylase, with a half-inhibitory concentration of 11.67 mg/mL. Amino acids were complexed with rice starch through heat-moisture treatment and the slowly digestible starch content significantly increased from 29.6 to 41.3 g/100 g. The interaction between amino acids and starch increased the ordered and aggregated structure of rice starch. Therefore, the enzyme inhibition and starch structure changes induced by amino acids contributed to the mitigation of starch digestion. These findings will improve our understanding of the relationship between amino acids and starch digestion and provide a theoretical basis for preparing starch-based food with a low glycemic index.
查看更多>>摘要：Microencapsulation is an effective technique for maintaining stability of labile bioactive components. However, as an indispensable process prior to microencapsulation, the effects of emulsion preparation on micro-encapsulated products are often overlooked. In this study, three industrialized comminution techniques (wet media milling, high pressure homogenization, and colloid milling method) were used to manufacture four lutein-loaded primary emulsions with different lutein particle size (from 238.2 nm to 2.2 mu m). Subsequently, lutein-loaded emulsions were microencapsulated through spray drying. The physicochemical properties, encapsulation efficiency, storage stability, and dissolution rate of lutein microencapsulated powder (LMPs) were examined to evaluate the effects of different emulsions on the quality of LMPs. Results indicated that the encapsulation efficiency and storage stability of LMPs decreased as the lutein particle size in emulsions increased. The LMP with smallest lutein particles possessed highest encapsulation efficiency (97.9%) and storage stability (plateau value of 89.44 and 78.85% at 25 degrees C and 40 degrees C). In vitro release study showed that apparent solubility and dissolution rate of LMPs containing nano-sized particle were significantly increased, compared with micron-sized LMPs and physical mixture. Our study suggested that preparing the emulsion containing nano-size lutein particles is critical for improving shelf life and oral bioavailability of this bioactive product.
查看更多>>摘要：Studies regarding the effects of extracellular polysaccharides produced by high-quality Kefiran production strains on the quality of yoghurt products and the mechanism of action during fermentation and production of yoghurt products are scarce in the literature. However, these studies are highly significant in the development of starters for the yoghurt industry. In this study, a Leuconostoc mesenteroides XR1 strain that produced exopolysaccharides (EPS) was identified and isolated from kefir grains collected from Xinjiang, China. XR1-EPS has similar flocculation characteristics to xanthan gum and higher emulsifying activity than locust gum. A rheological test of the dairy product sample after fermentation of XR1 single bacteria proved that XR1-EPS can impart higher viscosity and elasticity to fermented milk. Results also showed that XR1-EPS can maintain the water-holding ability of the fermented milk and provide a positive thixotropic fluid. In this study, XR1-EPS was isolated in the laboratory for the first time and was shown to be useful as a natural organic additive that can replace chemical additives in dairy products.
查看更多>>摘要：In this study, the effects of different extraction temperatures (45, 60 and 75 degrees C) and pH (3 and 5) on the physical and functional properties of tilapia skin gelatin (TSG) were investigated. The extraction yield of TSG is from 11.67 to 41.91% (based on dry weight), and the highest was obtained at 75 degrees C/pH 3. The TSG extracted at 45 degrees C showed strong band intensity of a-chains and cross-linked components with higher molecular weight (MW) > 120 kDa, while other TSG samples resulted in faded bands with the presence of fragments (<85 kDa). Higher contents of imino were detected in TSG with higher MW. Gel strength, apparent viscosity, and gelling temperature varied with different extraction temperatures and pHs, where higher values were observed in TSG with higher MW. These results are supported by circular dichroism analysis, in which more triple helix structures were found in TSG with higher MW. All TSG solutions can form gels at 4 degrees C, while at room temperature, only TSG obtained at 45.C can set. These results highlight the significance of extraction conditions which may be used to tailor the physical and functional properties of TSG.
查看更多>>摘要：Microwave processing is a novel technology in shortening food processing time and improving product quality. These advantages are achieved through the thermal and possible non-thermal effects of microwave. The main objective of the study was to explore the non-thermal effects of microwave electromagnetic (EM) fields on quality traits of pasteurized Oncorhynchus keta Walbaum fillets. A single-mode microwave processing system processed the fillets with a pasteurization thermal lethality value of F90 = 10 min. Corresponding pasteurization process with synchronous heating was designed to match the time-temperature profile of microwave processing. Retort pasteurization was used as a conventional process to compare the fillet quality performance with microwave pasteurization. With the pasteurization thermal treatment level, the proportion of six free amino acids was significantly different (P < 0.05) between the microwave pasteurized fillets and synchronous heating pasteurized fillets. The result could be attributed to the non-thermal effects of microwave EM fields. Compared with the retort pasteurization, the microwave process performed better in overall quality. Results suggested that microwave pasteurization exerted non-thermal effects in individual quality traits and caused less damage to fillet quality than the retort process in overall quality.
查看更多>>摘要：Pickering emulsion templating is a versatile technique in formulating highly networked oil-in-water emulsions applicable in foods, cosmetics, and pharmaceuticals areas. In this work, oleogels was prepared by oil-in-water Pickering emulsions using regenerated chitin (RCh) as the stabilizing particles. The effects of RCh concentrations (0.4/100-1.4 g/100 g) on the formation, rheology, and log-term stability of the emulsions and oleogles were investigated. It was found that the solid-like oloegel with a high concentration of liquid oil (>= 98 g/100 g) could be obtained after evaporating of water from the emulsions. Shear-thinning behavior was observed at lower concentrations of RCh (0.4-0.6 g/100 g) and higher frequencies in the emulsions. An increase in the viscoelastic property was achieved. Oleogels containing higher concentrations of RCh (0.8/100-1.4 g/100 g) showed excellent resistance against coalescence and Ostwald ripening during the storage time. These oleogels also showed good thermal stability (no sign of oil leakages) when heated to 80 degrees C for 2 days. This emulsion templating approach is a feasible oil structuring strategy promising to be used in various applications.
查看更多>>摘要：A-type proanthocyanidins (PACs) with health benefits such as prevention of urinary-tract infections are less common in food. Anthocyanins can directly condense with epicatechins to give rise to A-type anthocyanin-epicatechin dimers linked by C4-C8 and C2-O-C7 bonds, analogues of A-type PACs. Cyanidin-3-glucoside, cyanidin-3-galactoside, and petunidin-3-rutinoside-(p-coumaroyl)-5-glucose are the major anthocyanins of Lonicera caerulea berry, black chokeberry, and Lycium ruthenicum Murray extracts, respectively. We investigated the reaction of these anthocyanins with epicatechin at different pH, with temperature-time combinations, and in aerobic and nonaerobic conditions. Nucleophilic addition of epicatechin to the flavylium form of anthocyanins occurred at pH 1.5-4.0. The A-type colorless dimers cyanidin-3-glucoside-epicatechin, cyanidin-3-galactoside-epicatechin, and petunidin-3-rutinoside-(p-coumaroyl)-5-glucose-epicatechin were observed under optimal conditions (pH 3.0, 90 degrees C-110 degrees C, 80-100 min, anaerobic). This indicated that berry extracts, containing only B-type PACs, can synthesize analogues of A-type PACs mainly found in cranberry after thermal treatment.
查看更多>>摘要：Fermentation of blueberry and grape mixed musts in a 1:1 ratio with 4 different yeast strains has been studied. In order to evaluate which yeasts maintain the highest content of phenolic compounds, color and antioxidant activity. The musts were fermented with four types of strains, of which three were commercial yeasts QA23, Elegance MP061, M05 Mead and one isolated from partially fermented musts of Pedro Ximenez, X5 (CECT131015). In addition to the use of these yeast strains, spontaneous fermentation with indigenous fruit yeasts was used as a control. First, it was shown that the use of yeast inocula reduced the fermentation time avoiding the latency phase where the yeast adapts to the fermentation medium of both fruits. Second, among the wines obtained, the control wine was the one losing the least total phenolic compounds and less antioxidant activity. However, wines obtained from fermentation with inoculum showed the least color loss and a higher content of anthocyanins and flavonols. In fact, the M05 Mead yeast obtained the lowest loss of color, total phenolic compounds, and antioxidant activity; and the highest concentration of anthocyanins and flavonols. Therefore, this yeast was the most appropriate for the winemaking of mixed blueberries and grapes musts.
查看更多>>摘要：The effects of emulsified lard and transglutaminase (TGase) on the characteristics of threadfin bream surimi gels were investigated. Results showed that irrespective of TGase addition, the storage and loss modulus of surimi paste decreased with the increasing emulsified lard content during gel formation. The breaking force and deformation of surimi gels decreased from 857.33 g to 16.91 mm to 234.14 g and 8.44 mm respectively, after the addition of emulsified lard (2.5 g/100 g surimi). With further increase in the concentration of emulsified lard, the breaking force decreased, and the deformation remained almost unchanged. However, the weakening effect of emulsified lard was restrained by TGase. Regardless of TGase addition, the lightness, yellowness, and juiciness of surimi gels increased with the emulsified lard concentrations. The disulfide cross-linking among myosin heavy chains (MHCs) in surimi gels was inhibited by the emulsified lard, and the covalent cross-linking among MHCs was promoted by TGase. Emulsified lard and TGase could promote the hydrogen bonds among protein molecules in surimi gels. The compact and dense 3D gel network was destroyed by the added emulsified lard but protected in the presence of TGase. Therefore, high-quality surimi products could be produced under the combined action of emulsified lard and TGase.
NSTL
Elsevier