Esterified wheat bran: Physicochemical properties, structure and quality improvement of Chinese steamed bread during refrigerated storage

To develop the application of wheat bran and improve the nutrition and anti-staling capacity of Chinese steamed bread (CSB), oleic acid-esterified wheat bran (OWB) was prepared by esterification of wheat bran with oleic acid, and its physicochemical properties, structure, and quality improvement for CSB during refrigerated storage were investigated. The hydrophilic-lipophilic balance value of OWB was 16.0, the maximum degree of substitution was 0.146, and its emulsifying capacity was similar to that of glycerol monostearate. The starch gelatinization degree of CSB containing 3 % OWB and the control decreased by 19.55 % and 27.12 % within 7 days of refrigerated storage, respectively, while the hardness of CSB with OWB was lower than that with wheat bran. OWB inhibited starch recrystallization and increased bound water in the corresponding CSB, which effectively delayed starch retrogradation. OWB had a positive emulsifying capacity and showed potential as a functional material for preventing retrogradation of starch-based foods.

Impact of soluble soybean polysaccharide on the gelatinization and retrogradation of corn starches with different amylose content

Polysaccharides have a significant impact on the physicochemical properties of starch, and the objective of this study was to examine the effect of incorporating soluble soybean polysaccharide (SSPS) on the gelatinization and retrogradation of corn starches (CS) with varying amylose content. In contrast to high-amylose corn starch (HACS), the degree of gelatinization of waxy corn starch (WCS) and normal corn starch (NCS) decreased with the addition of SSPS. The inclusion of SSPS resulted in reduced swelling power in all CS, and led to a decrease in gel hardness of the starches. The intermolecular forces between SSPS and CS were primarily hydrogen bonding, and a gel network structure was formed, thereby retarding the short-term and long-term retrogradation of CS. Scanning electron microscopy results revealed that the addition of SSPS in starches led to a loose network structure with larger poles and a reduced ordered structure after retrogradation, as observed from the cross-section of formed gels. These findings suggested that SSPS has great potential for applications in starchy foods, as it can effectively retard both gelatinization and retrogradation of starches.

The formation mechanism and textural properties of a complex gel based on soybean glycinin-chitosan complex coacervates: Effects of pH, heat treatment temperature and centrifugation

The soybean glycinin (11S)-chitosan (CS) complex gels with various textural properties were successfully constructed. The process involved the initial formation of 11S-CS coacervates through electrostatic interactions, followed by a heating treatment to obtain the final complex gels. The impacts of pH, heating temperature, and centrifugation on 11S-CS complex gel properties were investigated. The results indicated that the pore arrangement of the gel formed at pH 7.3 was more tightly and uniformly packed than those formed at pH 6.8 and 7.8. Centrifugation facilitated denser and more ordered gel structures at the three pH values, while increasing the heating temperature exhibited the opposite trend at pH 6.8 and 7.8. These structural differences were also reflected in the rheological and textural properties of the gel. The 11S-CS complex gels exhibited an elasticity-based gel property. The textural properties of gels formed at pH 6.8 were stronger compared to those formed at pH 7.3 and 7.8. However, when the 11S-CS coacervates were heated without centrifugation, the resulting gels were weak. This study emphasizes the potential of using protein/polysaccharide associative interactions during gel formation to alter the microstructure of the gel, meeting various production requirements.

Modulation of soy protein isolate gel properties by a novel "two-step" gelation process: Effects of pre-aggregation with different divalent sulfates

A novel pre-aggregation process prior to gelation was applied to modulate the aggregation and gelation pathway of soy protein isolate (SPI). SPI dispersions were pre-aggregated with CaSO₄, MgSO₄ or ZnSO₄ at 0-15 mM and then gelled by adding CaSO₄ up to a final salt concentration of 35 mM. Compared with the sample without pre-aggregation, the storage modulus of SPI gels pre-aggregated with 10 mM CaSO₄, 10 mM MgSO₄, and 2.5 mM ZnSO₄ were increased by 50.5%, 35.7%, and 63.6%, respectively. The fracture stress, texture profile analysis parameters, and water holding capacity were markedly improved by an appropriate level of pre-aggregation. To a certain extent, pre-aggregation could promote the formation of uniform structure with thicker strands, whereas over-aggregation resulted in a coarser network, which was correlated with the volume-mean diameter (D_4,3) of pre-aggregated SPI particles. The results are of great value for further understanding of gelation mechanism of proteins.

Effects of Konjac glucomannan with different viscosities on the rheological and microstructural properties of dough and the performance of steamed bread

Konjac glucomannan (KGM) is used as an additive to improve the properties of wheat products. The effects of three types of KGM on the rheological properties and microstructure of dough, as well as the performance of steamed bread were investigated in this study. Particularly, dough with KGM displayed new features such as reduced peak viscosity, breakdown and setback. As the viscosity of KGM increased, the stability of the dough structure increased, while the viscosity and fluidity of the dough decreased. More interestingly, the gluten film of dough also increased with increasing substitution level and viscosity of KGM. Consistently, KGM with higher viscosity improved the quality of steamed bread. Generally, three types of KGM have different effects on the rheological characteristics and microstructure of dough, as well as the performance of steamed bread, which provide useful information for the proper application of KGM in wheat-based foods.

A comparative study on the textural and nutritional profile of high pressure and minimally processed pineapple

High pressure processing of pineapple has potential implication in food industry. The impact of high pressure (HP) processing and minimal processing, on quality parameters of pineapple was analysed. Changes in the pineapple quality in terms of texture, colour, total flavonoids, total polyphenols, vitamin C and sensory properties were investigated within the domain of 100-300 MPa and 5-20 min. Quality changes induced by HP processing was compared with the minimally processed pineapple. High pressure processing significantly (p < 0.0001) affect the firmness, total flavonoids, total polyphenols, vitamin C and colour values and were significantly increased in HP processed samples, while in minimal processed samples, these quality attributes exhibited a major degradation. On the basis of quality analysis, microbial quality and sensory assessment, high pressure treatment at 300 MPa for 10 min was found to be suitable for preserving the quality of pineapple up to 16^th day in refrigeration condition.

Effect of amaranth and quinoa seed flour on rheological and physicochemical properties of goat meat nuggets

An attempt was made through the present study to prepare gluten free goat meat nuggets by replacing refined wheat flour from product formulation with healthy, dietary fibre rich amaranth (A) and quinoa (Q) flour at different levels. A total of five different treatments viz., AI (1.5% amaranth), AII (3% amaranth), QI (1.5% quinoa) and QII (3% quinoa) were prepared. The physicochemical, colour, texture, sensory and rheological properties of these pseudocereal-added products were evaluated against control (3% refined wheat flour). Emulsion stability of meat batter was significantly affected (P < 0.05) due to addition of amaranth flour (1.5% and 3%) and quinoa (3%). Treatment groups AII and QI had significantly low (P < 0.05) moisture content with respect to control while the amount of fat content showed a reverse trend. Addition of amaranth and quinoa significantly increased (P < 0.05) the dietary fibre in meat products. Rheology of meat batter was affected by types and level of pseudocereal incorporation. Treatment AII had low (P < 0.05) hunter colour lightness value, whereas redness value was low for treatment QI. Effect of added amaranth and quinoa flour was observed on the textural parameters like adhesiveness, cohesiveness, gumminess and chewiness. High scores for almost all the sensory parameters were recorded in pseudocereal-added meat products. Though, all the products were very much acceptable, product with 1.5% quinoa flour was found to have high (P < 0.05) overall acceptability score.

Structural, rheological and antioxidant properties of pectins from Equisetum arvense L. and Equisetum sylvaticum L

The pectins were isolated from sterile stems of E. arvense (EA, yield 5.9%) and E. sylvaticum (ES, yield 4.8%) (Equisetaceae) using ammonium oxalate extraction after preliminary treatment with dilute HCl (рH 4.0). The pectins possessed high molecular weight (Mw, 340-360 kDa), high GalA content (ca. 85%), low degrees of methyl-esterification (14-16%) and acetylation (3-8%). NMR analysis indicated extensive regions of partially methyl-etherified and 3-O-acetylated HG and minor regions of low branched RG in the fragment isolated after hydrolysis of pectin EA by pectinase. Pectin EA produced a higher viscosity solution, formed a stronger and more rigid ionotropic hydrogel than pectin ES. The pectins scavenged DPPH and hydroxyl radicals, but not the superoxide radical and hydrogen peroxide. Phenolic compounds (0.11 and 0.23%) associated with polysaccharide moieties were apparently responsible for the differences in the anti-DPPH scavenging activity of pectins EA and ES (63 and 49%). The findings suggested that pectin from E. arvense should be more perspective than pectin from E. sylvaticum on their use as components of wound healing remedies.

Effect of different alkali treatments on the chemical composition, physical properties, and microstructure of pidan white

Changes in chemical composition, physical property and microstructure of pidan white treated with 4.5 % NaOH or 5.5 % KOH were monitored during pickling up to 4 weeks, and followed by aging for another 2 weeks. As the pickling and ageing times increased, moisture content of pidan white decreased and salt content increased for both (4.5 % NaOH and 5.5 % KOH) treatments (P < 0.05). Free alkalinity and pH of pidan white treated with 4.5 % NaOH increased as pickling proceeded, but decreased during ageing for both pickling treatments (P < 0.05). At week 4 of pickling, pidan white treated with 5.5 % KOH had higher hardness, cohesiveness, gumminess and chewiness than those treated with 4.5 % NaOH. After ageing, higher springiness, elastic modulus (G') and viscous modulus (G") were generally found in pidan white treated with 5.5 % KOH (P < 0.05). As the pickling time increased, lower L*, b* values and higher a* value were observed in pidan white from both treatments (P < 0.05). As visualized by scanning electron microscope, the aggregation of egg proteins took place in pidan white gels, irrespective of pickling treatments used. Nevertheless, closer and more orderly protein aggregates with denser network were founded in pidan white treated with 5.5 % KOH.