Effect of pigskin gelatin on baking, structural and thermal properties of frozen dough: Comprehensive studies on alteration of gluten network

Effect of freezing rates on α-amylase enzymatic susceptibility, in vitro digestibility, and technological properties of starch microparticles

The aim of this study was to evaluate the effect of freezing rates using direct (LF: Liquid nitrogen) and indirect (RF: Cryogenic refrigerator and UF: ultra-freezer) methods at temperatures of (-20, -80, and - 196 °C) on the enzymatic susceptibility with α-amylase for microparticles. In vitro digestibility parameters and technological properties were also analyzed. Lower rates resulted in larger ice crystals, damaging the starch structure. Hydrolysis was more pronounced at slower rates RF: 0.07 °C/min and UF: 0.14 °C/min, yielding maximum values of RDS: 37.63% and SDS: 59.32% for RF. Type A crystallinity remained unchanged, with only a noted increase in crystallinity of up to 6.50% for FR. Starch pastes were classified as pseudoplastic, with RF exhibiting superior textural parameters and apparent viscosity. (RF: 7.18 J g-1 and UF: 7.34 J g-1) also showed lower values of gelatinization enthalpy. Freezing techniques were viable in facilitating the diffusion of α-amylase and reducing RS by up to 81%.

The impact of magnetic field-assisted freeze-thaw treatment on the quality of foxtail millet sourdough and steamed bread

Foxtail millet and sourdough are used to make foxtail millet sourdough steamed bread to improve the flavor and taste. Compared with the conventional freeze-thaw treatment (CFT), the effect of magnetic field-assisted freeze-thaw treatment (MFT) on the storage quality of foxtail millet sourdough and steamed bread is explored. The results showed that compared with CFT, MFT shortened the phase transition time of dough; decreased the water loss rate, the water mobility, and the freezable water content; increased the fermentation volume; stabilized the rheological properties; and minimized the damage of freezing and thawing to the secondary structure and microstructure of the gluten. In addition, an analysis of the specific volume, texture, surface color, and texture structure showed that MFT was beneficial to slowing the deterioration of the steamed bread texture. Finally, MFT effectively inhibited the growth and recrystallization of ice crystals during freezing and thawing, improving the quality of millet dough and steamed bread.

Effects of different thawing methods on physical and physicochemical properties of frozen dough and quality of corresponding steamed bread

The thawing method is critical for the final quality of products based on the frozen dough. The effects of ultrasound thawing, proofer thawing, refrigerator thawing, water bath thawing, ambient thawing, and microwave thawing on the rheology, texture, water distribution, fermentation characteristics, and microstructure of frozen dough and the properties of steamed bread were investigated. The results indicated that the ultrasound thawing dough had better physicochemical properties than other doughs. It was found that ultrasound thawing restrained the water migration of dough, improved its rheological properties and fermentation capacity. The total gas volume value of the ultrasound thawing dough was reduced by 21.35% compared with that of unfrozen dough. The ultrasound thawing dough displayed a thoroughly uniform starch-gluten network, and an enhanced the specific volume and internal structure of the steamed bread. In conclusion, ultrasound thawing effectively mitigated the degradation of the frozen dough and enhanced the quality of steamed bread.

Effects of freeze-thaw cycles on the quality of Hot-dry noodles: From the moisture, starch, and protein characteristics

Freeze-thaw cycles (FTC) could cause damage to food during storage. The effects of different FTC on Hot-dry noodles (HDN) in terms of quality, moisture, starch, and protein characteristics were studied. This study showed that FTC decreased the texture properties and water absorption of HDN. Meanwhile, cooking loss was significantly increased after FTC. The water content of HDN was decreased and water migration was increased during FTC. In addition, results showed that FTC destroyed the order structure and increased the crystallinity of starch in HDN. Under FTC, the disulfide bond of HDN was broken, the free sulfhydryl group was increased, and the electrophoretic patterns confirmed the protein depolymerization. The microstructure also showed that the gluten network became incomplete and starch was exposed outside the substrate. This study expounded the mechanism of HDN quality deterioration during FTC, which laid a foundation for the development and improvement of frozen and freeze-thaw noodles.

Effects of improver on the quality of frozen Chinese sweet rice wine dough: Water status, protein structure and flavor properties

In the study, a sweet wine koji (YQ-5) was successfully selected to make frozen Chinese sweet rice wine dough (F-CD) for flavor enrichment. Subsequently, the effects of single improver (SI: xanthan gum, potassium carbonate, antifreeze protein, diacetyl tartaric esters of monoglycerides and composite improver (XPADG: Four improvers mixed in proportion) on the texture, rheological properties, microstructure, water status, protein secondary structure, volatile flavor substances and sensory properties of F-CD during frozen storage were investigated. The results indicated that XPADG slowed the increase in freezable water and water mobility in the dough, giving dough the most stable rheological properties and minimizing the damage of freezing to the secondary structure and microstructure of proteins. Besides, GC-QTOF/MS analysis showed that XPADG may facilitate the retention of flavoring substances in F-CD after storage for 6 days. Finally, the sensory evaluation showed that XPADG imparted good sensory properties to the product after freezing for 6 days.

Effects of apple fiber on the physicochemical properties and baking quality of frozen dough during frozen storage

The effects of apple fiber on gluten structure and corresponding frozen dough quality during frozen storage were studied. The addition of 0.50% and 0.75% apple fiber effectively preserved gluten structure by inhibiting the breakage of disulfide bonds and promoting the formation of hydrogen bonds. Notably, the presence of 0.75% apple fiber increased the β-turn of gluten from 29.60% to 33.84%. Fiber-enriched frozen dough exhibited a smoother and more compact microstructure, but excessive fiber addition (more than 1.00%) had adverse effects. The freezable water content of frozen dough decreased as fiber addition increased. Correspondingly, the addition of 1.50% apple fiber resulted in a 56.08% increase in storage modulus, indicating improved viscoelasticity of the dough. Consequently, the addition of 0.50% and 0.75% apple fiber alleviated the quality deterioration of frozen dough bread in terms of larger specific volume, softer and more uniform crumb.

Monitoring the Dough Properties, Quality Characteristics and Volatile Compounds of Whole Wheat Bread Made by Different Sourdough Types during Frozen Storage

There is a need to increase the consumption of whole wheat bread (WWB) due to its health benefits by overcoming its poor technological quality and improving its sensory characteristics. In this study, sourdough bread-making and frozen dough technology were combined to provide fresh WWB at any time with better quality. Also, it was aimed to investigate the effects of three types of sourdough (type I, II, and IV) on the final quality of WWB during frozen storage (-30 °C, 14 and 28 days). The tan δ of WWB with type I sourdough was highest at the end of the frozen storage. Freezable water content was lower on day 0 for WWB with type II and IV sourdough than other bread types. No significant effect of frozen storage was observed in bread types in terms of an α helix structure, except for WWB with type I sourdough. A lower hardness increment was shown in WWB with baker's yeast and WWB with type II sourdough over 14 days of frozen storage when compared to other bread types. WWB with type I sourdough and WWB with type IV sourdough were differentiated from other bread samples in volatile compound (VC) analysis on frozen storage days 28 and 0, respectively. The frozen storage of WWB with baker's yeast and WWB with type II sourdough caused no notable changes in the VCs profile. These results suggest that a less detrimental effect of frozen storage was observed in WWB with type II sourdough, indicating a more favorable choice for producing WWB with sourdough.

Quality attributes and functional properties of whole wheat bread baked from frozen dough with the addition of enzymes and hydrocolloids

BACKGROUND

The increased demand for healthy and standardized bread has led to a demand for an efficient and promising dough improver, of natural origin, to reduce the deterioration of whole wheat bread baked from frozen dough caused by the high levels of dietary fiber and by freezing treatment. In this study, the combined effects of xylanase (XYL), lipase (LIP), and xanthan gum (XAN) on the quality attributes and functional properties of whole wheat bread baked from frozen dough were evaluated.

RESULTS

The optimal combination, which contained XYL (0.12 g kg-1 ), LIP (0.25 g kg-1 ), and XAN (3.1 g kg-1 ), was obtained using response surface methodology (RSM). The addition of the optimal combination endowed frozen dough bread with a higher specific volume, softer texture, better brown crumb color, and greater overall acceptability. The optimal combination had no adverse impact on the volatile organic compounds (VOCs) of frozen dough bread. In terms of the functional properties of bread, the water-holding capacity (WHC), oil-holding capacity (OHC), and swelling capacity (SWC) of dietary fiber in frozen dough bread decreased in the presence of the optimal combination, whereas the glucose adsorption capacity (GAC) did not affect them. Correspondingly, the in vitro digestive glucose release was not significantly different between the control group and the optimal combination group after frozen storage.

CONCLUSION

The optimal combination could improve the quality attributes and functional properties of whole wheat bread baked from frozen dough effectively, thereby increasing consumption. © 2023 Society of Chemical Industry.

Collagen and gelatin: Structure, properties, and applications in food industry

Food-producing animals have the highest concentration of collagen in their extracellular matrix. Collagen and gelatin are widely used in food industry due to their specific structural, physicochemical, and biochemical properties, which enable them to improve health and nutritional value as well as to increase the stability, consistency, and elasticity of food products. This paper reviews the structural and functional properties including inherent self-assembly, gel forming, water-retaining, emulsifying, foaming, and thickening properties of collagen and gelatin. Then the colloid structures formed by collagen such as emulsions, films or coatings, and fibers are summarized. Finally, the potential applications of collagen and gelatin in muscle foods, dairy products, confectionary and dessert, and beverage products are also reviewed. The objective of this review is to provide the current market value, progress as well as applications of collagen and its derivatives in food industry.

Effects of Fish Skin Gelatin Hydrolysates Treated with Alcalase and Savinase on Frozen Dough and Bread Quality

Fish skin gelatin, as a waste product of sea bream, was used to obtain fish gelatin hydrolysate (FGH) with the treatment of alcalase (alc) and savinase (sav). The functional properties of FGHs and their usage possibilities in frozen dough bread making were investigated. FGH treated with alc showed a higher emulsifying stability index (189 min), while FGH treated with sav showed greater foaming capacity (27.8%) and fat-binding capacity (1.84 mL/g). Bread doughs were produced using two FGHs (alc and sav) and their combination (FGH-alc + FGH-sav). Using FGH treated with these enzymes individually was more effective than their combination in terms of polyacrylamide gel electrophoresis (SDS-PAGE) results and bread quality (specific volume and hardness). The addition of FGH into bread dough showed no significant effect on bread dough viscoelasticity (tan δ), while the increment level of tan δ value for control dough was higher than the dough containing FGH after frozen storage (-30 °C for 30 days). The highest freezable water content (FW%) was found in control dough (33.9%) (p < 0.05). The highest specific volume was obtained for control fresh bread and bread with FGH-alc, while the lowest volume was obtained for fresh bread containing FGH-sav (p < 0.05). After frozen storage of the doughs, the bread with FGH-alc showed the highest specific volume. FGH addition caused a significant reduction in the L* (lightness) value of fresh bread samples when compared to control bread (p < 0.05). This study suggested that usage of FGH-alc in bread making decreased the deterioration effect of frozen storage in terms of the specific volume and hardness of bread.

Effects of Casein Hydrolysate Prepared with Savinase on the Quality of Bread Made by Frozen Dough

The effect of casein savinase hydrolysate (CSH) usage on frozen dough (1%, 1.5% and 2%, g/100 g flour) was investigated in terms of rheological, thermal and structural characteristics of wheat doughs and the textural and color properties of corresponding breads. Rheological measurements showed that CSH addition into dough led to a reduction in G' and G″ values, but a similar trend was not observed in frozen dough samples. The increase in protein band intensity was observed for control dough (CD) after frozen storage (-30 °C, 28 days), while there were no increases in the band intensities of the doughs with CSH. The freezable water content of unfrozen doughs decreased gradually with the addition of CSH, dependent on concentration level. Frozen storage caused a notable reduction in the α-helices structure of the CD sample (p < 0.05) while no significant variation was observed for the doughs containing CSH (p > 0.05). The lowest specific volume reduction and hardness increment were observed for the breads containing 1.5% and 2% CSH. Frozen storage caused a significant reduction in the b* value of bread crust (p < 0.05), while no significant effect was observed for L* and a* value during frozen storage (p > 0.05). Overall, CSH incorporation into frozen dough can be an alternative that could reduce the quality deterioration of frozen bread.

Use of a compound modifier to retard the quality deterioration of frozen dough and its steamed bread

To retard the quality deterioration of the dough during frozen storage, the effects of a compound modifier (CM) comprised of sodium stearoyl lactate, VC, and β-glucanase on the properties of the frozen dough, as well as the quality of the frozen dough steamed bread were investigated. The results revealed that CM restricted the migration of water in the dough and improved its rheological properties. Furthermore, CM minimized the deterioration of specific volume and textural properties, and prevented starch retrogradation in the frozen dough steamed bread. Moreover, the addition of CM strengthened the secondary structure of gluten protein and formed a more resilient gluten network. The microstructure of the frozen dough steamed bread showed that CM reduced the damage caused by ice crystals on the gluten network. Overall, the use of CM strengthened the gluten network and effectively delayed the quality deterioration of the frozen dough, thus is potential as an improver for frozen dough.

Structural, rheological and functional properties of ultrasonic treated xanthan gums

Xanthan gum can improve the freeze-thaw stability of frozen foods. However, the high viscosity and long hydration time of xanthan gum limits its application. In this study, ultrasound was employed to reduce the viscosity of xanthan gum, and the effect of ultrasound on its physicochemical, structural, and rheological properties was investigated using High-performance size-exclusion chromatography (HPSEC), ion chromatograph, methylation analysis, 1H NMR, rheometer, etc.. The application of ultrasonic-treated xanthan gum was evaluated in frozen dough bread. Results showed that the molecular weight of xanthan gum was reduced significantly by ultrasonication (from 3.0 × 107 Da to 1.4 × 106 Da), and the monosaccharide compositions and linkage patterns of sugar residues were altered. Results revealed that ultrasonication treatment mainly broke the molecular backbone at a lower intensity, then mainly broke the side chains with increasing intensity, which significantly reduced the apparent viscosity and viscoelastic properties of xanthan gum. The results of specific volume and hardness showed that the bread containing low molecular weight xanthan gum was of better quality. Overall, this work offers a theoretical foundation for broadening the application of xanthan gum and improving its performance in frozen dough.

Ice Recrystallization Inhibition Activity of Soy Protein Hydrolysates

Identifying and developing ice recrystallization inhibitors from sustainable food proteins such as soy protein isolate (SPI) can lead to practical applications in both pharmaceutical and food industries. The objective of this study was to investigate the ice recrystallization inhibition (IRI) activity of SPI hydrolysates, and this was achieved by using an IRI activity-guided fractionation approach and relating IRI activity to interfacial molecular activity measured by vibrational sum frequency generation (VSFG). In addition, the impact of molecular weight (MW) and enzyme specificity was analyzed using three different proteases (Alcalase, trypsin, and pancreatin) and varying hydrolysis times. Using preparative chromatography, hydrolysates from each enzyme treatment were fractionated into five different MW fractions (F1-F5), which were then characterized by high-performance liquid chromatography (HPLC). All SPI hydrolysates had IRI activity, resulting in a 57-29% ice crystal diameter reduction when compared to native SPI. The F1 fraction (of 4-14 kDa) was most effective among all tested hydrolysates, while the lower MW peptide fractions lacked activity. One sample (SPI-ALC 20-F1) had a 52% reduction of ice crystal size at a lower concentration of 2% compared to the typical 4% used. SFG showed a difference in H-bonding and hydrophobic interactions of the molecules on the water/air interface, which may be linked to IRI activity. This study demonstrates for the first time the ability of SPI hydrolysates to inhibit ice crystal growth and the potential application of SFG to study molecular interaction at the interface that may help illustrate the mechanism of action.

The Effect of Co-Fermentation with Lactobacillus plantarum HLJ29L2 and Yeast on Wheat Protein Characteristics in Sourdough and Crackers

Sourdough fermentation has been widely used in food products. However, there has been limited study of the effect of co-fermentation with lactic acid bacteria and yeast on the dough and cracker products. In this study, the influence of co-fermentation with Lactobacillus plantarum HLJ29L2 (LP HLJ29L2) and yeast on wheat protein digestibility of cracker was studied, and the mechanism of the protein changes in sourdough during fermentation was further explored. Co-fermentation with LP HLJ29L2 and yeast (DN-1) strongly improved the protein digestibility of cracker. At the same time, the content of free amino acids in DN-1 crackers increased by 20%. Co-fermentation also had significant effect on the sourdough during fermentation. The SDS-soluble protein content in sourdough was increased, and large molecule proteins were significantly reduced in the DN-1 sourdough. This was due to the fact, that LP HLJ29L2 grew rapidly during co-fermentation and produced more organic acids, which led to an increase in protease activity in sourdough and promoted the degradation of protein by proteases. The results of this study provide an important theoretical basis for the application of lactic acid bacteria and yeast co-fermentation in crackers.

Comparative study of soluble soybean polysaccharides on bread staling under acidic conditions

Effect of soluble soybean polysaccharides (SSPS) and acidic condition on the bread staling of crumb and crust were evaluated in bread characteristics, water migration, starch retrogradation, and flavor. Bread characteristic analysis showed SSPS and acidic conditions significantly improved bread quality during storage, maintaining crumb softness. The staling rate of the synergistic group under SSPS and acidic condition decreased by 49.46% compared to the control group. This retardation was associated with water migration and starch retrogradation. SSPS and acidic conditions restricted the water migration from crumb to crust. A synergy between SSPS and acidification restrained the relative crystallinity and retrogradation enthalpy in bread crumbs and crust during storage. The scores plot and heat map analysis indicated SSPS and acidic condition was facilitated the flavors retention in the crumb and crust after stored 7-days. This study suggested SSPS and acidic conditions might be beneficial for extending bread shelf-life.

Identification of Novel Antifreeze Peptides from Takifugu obscurus Skin and Molecular Mechanism in Inhibiting Ice Crystal Growth

Foodborne hydrolyzed antifreeze peptides have been widely used in the food industry and the biomedical field. However, the components of hydrolyzed peptides are complex and the molecular mechanism remains unclear. This study focused on identification and mechanism analysis of novel antifreeze peptides from Takifugu obscurus skin by traditional methods and computer-assisted techniques. Results showed that three peptides (EGPRAGGAPG, GDAGPSGPAGPTG, and GEAGPAGPAG) possessed cryoprotection via reducing the freezing point and inhibiting ice crystal growth. Molecular docking confirmed that the cryoprotective property was related to peptide structure, especially α-helix, and hydrogen bond sites. Moreover, the antifreeze peptides were double-faces, which controlled ice crystals while affecting the arrangement of surrounding water molecules, thus exhibiting a strong antifreeze activity. This investigation deepens the comprehension of the mechanism of antifreeze peptides at molecular scale, and the novel efficient antifreeze peptides can be developed in antifreeze materials design and applied in food industry.

Aggregation properties and structure of chia seed gum and gluten protein mixtures after freezing storage

Chia seed gum (CSG) plays an important role in the aggregation and structural properties of gluten protein. The experimental results showed that adding 1.0 % CSG increased the freezing rate and shortened the freezing time by 42.3 % compared with gluten without CSG. At the same time, CSG had no significant effect on the composition of the gluten subunit but could better control the change in binding water and delay the structural deterioration caused by the extension of time (30 d). The viscoelasticity of gluten was increased, but only with the addition of 0.2-0.6 % CSG. In addition, it increased the denaturation transition temperature (Tp) and the degradation temperature (Td) of gluten protein to reduce the occurrence of recrystallization and resist pyrolysis. During frozen storage, gluten can form fine ice crystals and inhibit the transformation of α-helices and β-turns to random coils and β-sheets, which is more conducive to long-term frozen storage.

Conformational and thermal properties of gluten in wheat dough as affected by bacterial cellulose

Bacterial cellulose (BC), an important category of polysaccharides, was investigated as a texture improver in bakery products. This study focused on the changes in the conformational and thermal properties of gluten in the wheat dough system as affected by BC. Significant reductions in the free-SH content, fluorescence intensity, and surface hydrophobicity index (H₀) were observed as a result of the increased BC addition. The electrophoresis profile (SDS-PAGE) and size exclusion (SE-HPLC) revealed the variation in molecular weight distribution, and the increase in the content of the 40-91 kDa molecular weight was at the expense of a decrease in the amount of the corresponding 10-40 kDa. When 0.1 % BC was added, both the α-helix and β-sheet contents increased as a result of enhanced chemical interactions, thereby contributing to the gluten matrix with higher thermal stability. Further supplementation interfered with the current ordered gluten structure, which could be supported by the lower α-helix/β-sheet content ratio and the decreased degradation temperature (T_d) of gluten with 0.2 % BC. However, the observed decrease in the ratio of β-turns to β-sheets and weight loss at 600 °C indicated that a reconstructed gluten matrix induced by extra BC addition was formed to maintain the structural stability.

Effect of pigskin gelatin hydrolysate on the porcine meat quality during freezing

This research aimed to investigate the effects of pigskin gelatin hydrolysate (PGH) on the quality changes of longissimus lumborum (LL) muscles during freezing. The samples were firstly assigned into six groups, including control, sucrose and sorbitol group (SUSO) as positive control, 0%, 1%, 2% and 4% PGH group. The thawing loss of frozen meat, microscopic observation of ice crystal formed during freezing, myowater mobility in muscle tissues, and protein structure changes were determined. PGH reduced the thawing loss of frozen meat by 5.32%. Microscopic observation showed that ice crystal area reduced to 15.54% with 4% PGH treatment. The PGH also reduced the loss of immolized water in meat during freezing. The Raman spectra showed that the protein structure remained more intact in the group of 4% PGH. It can be concluded that the addition of PGH effectively diminished the deterioration of muscle qualities, enhanced the cryoprotective of the muscles during freezing, and this enhancement was associated with their increasing amount.

Alteration in dough volume and gluten network of lychee pulp pomace bread base on mixture design dominated by particle size

The reducing flavor of whole grain bread has been constantly affecting the consumption desire of a significant proportion of consumers. The study presents the use of lychee pulp pomace (LPP) powder to replace certain proportion of wheat flour and produce wheat bread with better quality, while having minimal effects on the volume and improving the nutritional quality. Distinct particle sizes (60-400 µm) of LPP powder were obtained by superfine or ordinary grinding. Effect of different additive proportions (7-19%) of LPP powder on bread dough quality were studied by constrained mixture designs. The volume of fermented doughs subsequently decreased after adding LPP powder. However, LPP powders with smaller particle sizes were able to minimize this effect due to its higher water-holding capacity. The analyses of gluten network showed that smaller particle sizes of LPP powder resulted in a decrease in surface hydrophobicity and increase in the elasticity and stability of gluten network. Finally, optimum mixture formula was composed of 16% LPP powder with 60 µm particle size and 15% water. The study illustrated the potential to make high-quality bread with small particle size of LPP powder. PRACTICAL APPLICATION: The addition of dietary fiber to wheat flour can adversely affect the dough volume and reduce the dough quality. By reducing the particle size of lychee pulp pomace powder, this adverse effect could be minimized while increasing the content of dietary fiber and bound phenolics in the dough. This provides data for the production of high-quality lychee dough bread.

Rheological, microstructure and mixing behaviors of frozen dough reconstituted by wheat starch and gluten

The effects of starch and gluten on the physicochemical properties of frozen dough were studied using reconstituted flour. The profiles of frozen dough were studied by Mixolab, rheometer, scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). Results revealed that starch, rather than gluten, played a decisive role in mixing properties. The breakdown and aggregation of the gluten network structure as well as the formation of β-turns and β-sheets in the frozen dough would be aggravated by the freezing of wheat starch. Smaller wheat starch granules (B-Type granules) affected the secondary structure of gluten network more than larger granules (A-Type granules), resulting in greater rheological property changes. The viscoelastic properties and freezable water content of frozen dough were more influenced by the freezing of gluten.

The dough-strengthening and spore-sterilizing effects of mannosylerythritol lipid-A in frozen dough and its application in bread making

Biosurfactants have been put into applications in breadmaking industry, while the effects of mannosylerythritol lipid-A (MEL-A) on gluten network of frozen dough, bread quality and microbial spoilage were firstly investigated in this study. Rheology and differential scanning calorimetry (DSC) analysis showed that MEL-A significantly improved the rheological properties of frozen dough and reduced the content of frozen water. Further experiments showed that MEL-A promoted the formation of aggregates by interacting with gluten protein, and strengthened the gluten network through molecular weight distribution measurement and microstructure observation, effectively avoiding the destruction of ice crystals. A series of bread assessments illustrated MEL-A improved the loaf volume, gas retention ability and textural property. In addition, MEL-A (1.5%) killed 99.97% of the vegetative cells of Bacillus cereus and 75.54% of the spores, and at the same time had a slight inactivation effect on yeast. These results indicate that MEL-A has broad application prospects in the baking industry and the storage stage of flour products.

Application of Gelatin in Food Packaging: A Review

Owing to the increasing environmental concerns and requirements for high-quality foods, edible films and coatings (based on proteins, polysaccharides, natural phenolic active substances, etc.) are being developed as effective alternatives to traditional plastic packaging. Gelatin is extracted from collagen. It is an ideal material for food packaging due to its versatile advantages such as low price, polymerization, biodegradability, good antibacterial and antioxidant properties, etc. However, gelatin film exists poor waterproof and mechanical properties, which limit its developments and applications in food packaging. Previous studies show that pure gelatin can be modified by adding active ingredients and incorporating them with bio-polymers to improve its mechanical properties, aiming to achieve the desirable effect of preservation. This review mainly shows the preparation and molding ways of gelatin-based edible films and the applications of gelatin modified with other biopolymers. Furthermore, this review provides the latest advances in gelatin-based biodegradable packaging and food applications that exhibit outstanding advantages in food preservation.

Effects of long-term frozen storage on the quality and acceptance of gluten-free cassava pasta

Cold storage conditions during long-term periods can be critical for the quality of gluten-free products. The objective of this work was to elaborate gluten-free pasta using cassava starch and study the influence of different storage conditions on the textural and sensorial properties of gluten-pasta compared to regular pasta. Samples were initially frozen at two different temperatures, -50 °C and -150 °C, and then stored for six months at -25 °C. Physicochemical and rheological analyses were used to characterize the pasta dough. Then microbiological, instrumental texture, and sensorial analysis were used to further characterize the pasta throughout the cold storage period of 6 months. The gluten-free pasta's nutritional composition showed low fat and protein content and high crude fiber, carbohydrates, and energy value content in relation to the gluten-containing pasta. Both kinds of pasta dough presented a pseudoplastic behavior; however, the wheat flour pasta presented lower apparent viscosity. The texture profile of frozen pasta during the evaluation period did not significantly vary when comparing the two freezing temperatures. Although the firmness, chewability, and cohesiveness parameters slightly decreased during the storage, losses of firmness were not detected by the judges at the sensorial analysis. Finally, cassava starch pasta had a high acceptance. According to the purchase intention research, the judges routinely consume gluten-free pasta, showing the high commercialization potential of the obtained product.

Understanding how starch constituent in frozen dough following freezing-thawing treatment affected quality of steamed bread

Understanding how starch constituent in frozen dough affected bread quality would be valuable for contributing to the frozen products with better quality. To elucidate the underlying mechanism, starch was fractionated from multiple freezing-thawing (F/T) treated dough and reconstituted with gluten. Results showed that F/T treatment destructed the molecular and supramolecular structures of starch, which were more severe as the F/T cycle increasing. These structural disorganizations made water molecules easier to permeate into the interior of starch granules and form hydrogen bonds with starch molecular chains, which elevated the peak, breakdown, setback and final viscosity of starch paste. In addition, F/T treatment resulted in decreased specific volume (from 1.54 to 0.90 × 10³ m³/Kg) and increased hardness (from 42.98 to 52.31 N) for steamed bread. We propose the strengthened water absorption ability and accelerated intra- and inter-molecular rearrangement of starch molecules and weak stability of "starch-gluten matrices" would allow interpreting deteriorated bread quality.

Understanding the influence of pullulan on the quality changes, water mobility, structural properties and thermal properties of frozen cooked noodles

Pullulan is widely applied in the food industry due to its unique physicochemical properties, but little information is known about its effects on the quality of frozen cooked noodles (FCNs), nor the underlying mechanism. In this study, the addition of 0.3% and 0.5% pullulan resulted in better texture and cooking properties, and minor chrominance differences, and it significantly (P < 0.05) decreased the freezable water content and retarded the water migration. Pullulan inhibited the depolymerization of the glutenin macropolymer during 0-8 weeks of frozen storage. Meanwhile, pullulan caused slightly decreased α-helixes and increased β-turns, as well as decreased degradation temperature, further suggesting that pullulan influenced the gluten network. A more compact microstructure was shown in the pullulan-fortified FCNs. This study provides a theoretical basis for the positive effects of pullulan on the quality of FCNs from the perspectives of water state and protein structure.

Changes of aggregation and structural properties of heat-denatured gluten proteins in fast-frozen steamed bread during frozen storage

The aim of this research was to clearly clarify the deterioration mechanism of heat-denatured gluten proteins by exploring the change of aggregation and structural characteristics of heat-denatured gluten proteins in the steamed bread system and the steamed gluten system during frozen storage. An increase in the total SDS-soluble protein content was determined, which mainly attributed to the soluble monomer protein content increased. Combined with the significant increase of free sulfhydryl, from 3.12 μmol/g to 5.06 μmol/g and 2.64 μmol/g to 3.29 μmol/g, respectively, it can be inferred that the proteins depolymerization induced by frozen storage was mainly involved in the breakdown of heat-induced glutenin-gliadin disulfide cross-linking. Frozen storage induced the conversion of random coil structure to β-sheet structure and a ruptured microstructure with small fragment was observed. Moreover, the protein of steamed bread system was easier to depolymerize than that of the steamed gluten system.

Animal by-products collagen and derived peptide, as important components of innovative sustainable food systems-a comprehensive review

In 2020, the world's food crisis and health industry ushered into a real outbreak. On one side, there were natural disasters such as the novel coronavirus (2019-nCoV), desert locusts, floods, and droughts exacerbating the world food crisis, while on the other side, the social development and changes in lifestyles prompted the health industry to gradually shift from a traditional medical model to a new pattern of prevention, treatment, and nourishment. Therefore, this article reviews animal by-products collagen and derived peptide, as important components of innovative sustainable food systems. The review also considered the preparation, identification, and characterization of animal by-product collagen and collagen peptides as well as their impacts on the food system (including food processing, packaging, preservation, and functional foods). Finally, the application and research progress of animal by-product collagen and peptide in the food system along with the future development trend were discussed. This knowledge would be of great significance for a comprehensive understanding of animal by-product collagen and collagen peptides and would encourage the use of collagen in food processing, preservation, and functional foods.

New insights into the alleviating role of starch derivatives on dough quality deterioration caused by freeze

The alleviating role of starch derivatives on the quality deterioration of frozen steamed bread dough was investigated in terms of derivative structure, the bread characteristics and dough properties including freezable water contents, yeast activity as well as dough viscoelasticity. The addition of starch derivatives including short-clustered maltodextrin (SCMD), DE2 maltodextrin (MD) and pregelatinized starch (PGS) significantly increased the specific volume and decreased the hardness of steamed bread compared with Control bread after 8-week frozen storage. Lower freezable water content was found in PGS dough than SCMD dough, which was consistent with the results of water absorption index of starch derivatives. The analysis of dough gassing rate and yeast survival ratio demonstrated SCMD could provide more cryoprotection for yeast cells. Meanwhile, a higher elastic module and a more continuous gluten-network structure of SCMD dough were found after 8-week frozen storage. These results indicated starch derivatives especially SCMD were promising to be used as the alternative improvers in frozen dough production.