Changes in protein oxidation, structure, and thermal stability of chicken breast subjected to ultrasound-assisted immersion freezing during frozen storage

Effects of bacterial cellulose/thyme essential oil emulsion coating on the shelf life of chilled chicken meat

BACKGROUND

Bacterial cellulose (BC) is a fiber substance produced by microbial fermentation. It is widely used in the food preservation industry because of its extremely pure texture, high crystallinity and high biocompatibility. In the present study, bacterial cellulose/thyme essential oil (BC/TEO-E) with antibacterial and fresh-keeping functions was prepared by ultrasonic treatment of modified bacterial cellulose for encapsulation of thyme essential oil, which effectively inhibited the spoilage of chilled chicken.

RESULTS

The purified BC, produced by Acetobacter xylinum ATCC 53524, was ultrasonically treated wih different times (0, 30, 60 and 90 min). Transmission electron microscopy, scanning electron microscopy, Fourier transformed infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and zeta potential were used to characterize the structure of BC after ultrasound, showing that BC, treated for 30 min, had the optimal fiber structure, crystallinity (85.8%), thermal stability (347.77 °C) and solution stability (-26.63 ± 1.96 mV). BC/TEO-E was prepared by a homogenizer for the preservation of chilled chicken. Optical microscopy indicated that the BC/TEO-E prepared by 0.5% BC had optimal dispersion and stability, and even no delamination was observed in the emulsion. Compared with other groups (control, 0.5% BC and Tween-E), the total number of colonies and coliforms in chilled chicken treated with 0.5% BC/TEO-E was the lowest during the whole storage period (12 days), indicating that it can effectively inhibit bacterial growth. In addition, total volatile base nitrogen (TVB-N), thiobarbituric acid reactive substances, pH and drip loss results showed that 0.5% BC/TEO-E could effectively inhibit the spoilage of chilled chicken compared to the other treatment groups.

CONCLUSION

All of the results acquired in the present study indicate that BC/TEO-E has a potential application in chilled chicken preservation. © 2024 Society of Chemical Industry.

Effect and mechanism of freezing on the quality and structure of soymilk gel induced by different salt ions

BACKGROUND

The increasing attention toward frozen soy-based foods has sparked interest. Variations exist in the quality and structure of soymilk gels induced by different salt ions, leading to diverse changes post-freezing. This study compared and analyzed the effects of calcium chloride (CC), magnesium chloride (MC) and calcium sulfate (CS) on the quality characteristics and protein structure changes of soymilk gels (CC-S, MC-S and CS-S) before and after freezing, and clarified the mechanisms of freezing on soymilk gel.

RESULTS

The formation rate of soymilk gel is influenced by the type of salt ions. In comparison to CS and MC, soymilk gel induced by CC exhibited the fastest formation rate, highest gel hardness, lowest moisture content, and smaller gel pores. However, freezing treatment deteriorated the quality of soymilk gel induced by different salt ions, leading to a decline in textural properties (hardness and chewiness). Among these, the textual state of CC-induced soymilk gel remained optimal, exhibiting the least apparent damage and minimal cooking loss. Freezing treatments prompt a transition of soymilk gel secondary structure from β-turns to β-sheets, disrupting the protein's tertiary structure. Furthermore, freezing treatments also fostered the crosslinking between soymilk gel protein, increasing the content of disulfide bonds.

CONCLUSION

The quality of frozen soymilk gel is influenced by the rate of gel formation induced by salt ions. After freezing, soymilk gel with faster gelation rates exhibited a greater tendency for the transformation of protein-water interactions into protein-protein interactions. They showed a higher degree of disulfide bond formation, resulting in a more tightly knit and firm frozen gel network structure with denser and more uniformly distributed pores. © 2024 Society of Chemical Industry.

Thawed drip and its membrane-separated components: Role in retarding myofibrillar protein gel deterioration during freezing-thawing cycles

Myofibrillar proteins are crucial for gel formation in processed meat products such as sausages and meat patties. Freeze-thaw cycles can alter protein properties, impacting gel stability and product quality. This study aims to investigate the potential of thawed drip and its membrane-separated components as potential antifreeze agents to retard denaturation, oxidation and gel deterioration of myofibrillar proteins during freezing-thawing cycles of pork patties. The thawed drip and its membrane-separated components of > 10 kDa and < 10 kDa, along with deionized water, were added to minced pork at 10 % mass fraction and subjected to increasing freeze-thaw cycles. Results showed that the addition of thawed drip and its membrane separation components inhibited denaturation and structural changes of myofibrillar proteins, evidenced by reduced surface hydrophobicity and carbonyl content, increased free sulfhydryl groups, protein solubility and α-helix, as compared to the deionized water group. Correspondingly, improved gel properties including water-holding capacity, textural parameters and denser network structure were observed with the addition of thawed drip and its membrane separation components. Denaturation and oxidation of myofibrillar proteins were positively correlated with gel deterioration during freezing-thawing cycles. We here propose a role of thawed drip and its membrane separation components as cryoprotectants against myofibrillar protein gel deterioration during freeze-thawing cycles.

Fluctuation of flavor quality in roasted duck: The consequences of raw duck preform's repetitive freeze-thawing

This study aimed to investigate the changes in flavor quality of roasted duck during repetitive freeze-thawing (FT, -20 ℃ for 24 h, then at 4 ℃ for 24 h for five cycles) of raw duck preforms. HS-SPME/GC-MS analysis showed that more than thirty volatile flavor compounds identified in roasted ducks fluctuated with freeze-thawing of raw duck preforms, while hexanal, nonanal, 1-octen-3-ol, and acetone could as potential flavor markers. Compared with the unfrozen raw duck preforms (FT-0), repetitive freeze-thawing increased the protein/lipid oxidation and cross-linking of raw duck preforms by maintaining the higher carbonyl contents (1.40 ∼ 3.30 nmol/mg), 2-thiobarbituric acid reactive substances (0.25 ∼ 0.51 mg/kg), schiff bases and disulfide bond (19.65 ∼ 30.65 μmol/g), but lower total sulfhydryl (73.37 ∼ 88.94 μmol/g) and tryptophan fluorescence intensity. Moreover, A lower protein band intensity and a transformation from α-helixes to β-sheets and random coils were observed in FT-3 ∼ FT-5. The obtained results indicated that multiple freeze-thawing (more than two cycles) of raw duck preforms could be detrimental to the flavor quality of the roasted duck due to excessive oxidation and degradation.

The effects of resonance acoustic mixing modulation on the structural and emulsifying properties of pea protein isolate

The effects of resonant acoustic mixing (RAM) with different treatment times (0, 5, 10, 15, 20 and 30 min) on the structural and emulsifying properties of pea protein isolate (PPI) were investigated for the first time. Increasing the RAM treatment time from 0 to 20 min decreased the α-helix/β-sheet ratio and particle size of the PPI samples by 37.84 % and 46.44 %, respectively, accompanied by an increase in solubility from 54.79 % to 71.80 % (P < 0.05). Consequently, the emulsifying activity index of PPI (from 10.45 m2/g to 14.2 m2/g) and the physical stability of RAM-PPI emulsions were effectively enhanced, which was confirmed by the small and uniformly distributed oil droplets in the micrographs of the emulsions. However, excessive RAM treatment (30 min) diminished the effectiveness of the aforementioned improvements. Therefore, obviously enhanced solubility and emulsifying properties of PPI can be attained through proper RAM treatment (15-20 min).

Characterization of ultrasound-assisted covalent binding interaction between β-lactoglobulin and dicaffeoylquinic acid: Great potential for the curcumin delivery

The low bioavailability and poor gastrointestinal instability of curcumin hampers its application in pharmaceutical and food industries. Thus, it is essential to explore efficient carrier (e.g. a combination of polyphenols and proteins) for food systems. In this study, covalent β-lactoglobulin (LG)-dicaffeoylquinic acids (DCQAs) complexes were prepared by combining ultrasound and free radical induction methods. Covalent interactions between LG and DCQAs were confirmed by analyzing reactive groups. Variations in secondary or tertiary structure and potential binding sites of covalent complexes were explored using Fourier transform infrared spectroscopy and circular dichroism. Results showed that the β-sheet content decreased and the unordered content increased significantly (P < 0.05). The embedding rate of curcumin in prepared LG-DCQAs complexes using ultrasound could reach 49 % - 62 %, proving that complexes could embed curcumin effectively. This study highlights the benefit of ultrasound application in fabrication of protein-polyphenol complexes for delivering curcumin.

Low-voltage electrostatic field enhances the frozen force of -12 ℃ to suppress oxidative denaturation of the lamb protein during the subsequent frozen storage process after finishing initial freezing

The effect of low-voltage electrostatic field (LVEF) assisted -9 °C (LVEF-9) and -12 °C (LVEF-12) frozen, non-LVEF-assisted -9 °C (NLVEF-9) and -12 °C (NLVEF-12) frozen, and conventional frozen (CF-18, -18 °C) storage on the muscle microstructure and the oxidative denaturation of the lamb protein during the subsequent frozen storage process after finishing initial freezing was investigated. Compared with NLVEF-9, LVEF-9, and NLVEF-12, LVEF-12 maintained the better integrity of muscle microstructure, demonstrated by smaller holes, more complete Z-line and M-line, and no significant difference with CF-18 (P > 0.05). Furthermore, LVEF-12 effectively inhibited protein oxidative denaturation as shown by the lower carbonyl content, surface hydrophobicity, and higher total/active sulfhydryl groups and Ca2+-ATPase activity. Moreover, LVEF-12 effectively maintained the integrity of the secondary and tertiary structure of proteins, reduced cross-linking aggregation of proteins, and sustained better functional properties, as shown by higher α-helix content, fluorescence intensity, protein solubility, and lower R-value, disulfide bonds.

Insights into the emulsifying effect and oxidation stability of myofibrillar protein-diacylglycerol emulsions containing catechin at different ionic strengths

The purpose of this study was to investigate the effects of different ionic strengths on the emulsifying and oxidation stabilities of myofibrillar protein-diacylglycerol emulsions containing catechin (MP-DAG-C), in which lard, unpurified glycerolytic lard (UGL), and purified glycerolytic lard (PGL) were used as oil phases in this study, respectively. Results revealed that emulsifying ability was significantly improved by UGL and PGL (P < 0.05). Meanwhile, the emulsifying activity and stability, absolute ξ-potential value, shear viscosity, and dynamic rheological characteristic of emulsions increased with the increase of ionic strength (P < 0.05) remarkablely, which reached the maximum value at 0.6-M sodium chloride (NaCl). The droplets of emulsions at 0.6-M ionic strength were smallest and distributed most uniformly compared to other NaCl conditions. The formation of thiobarbituric acid substances and carbonyls increased, and the total sulfydryl contents decreased as the extension of storage days (P < 0.05). However, the oxidation stability of MP-DAG-C emulsions was insignificantly decreased by ionic strengths (P > 0.05). The above results showed that MP-DAG-C emulsions could keep excellent emulsifying effects and oxidation stability under high ionic strengths. This study provides data support for the application of MP-DAG-C emulsions in emulsified meat products, which is benefit for promoting the development of high-quality emulsified meat products.

Tracking protein aggregation behaviour and emulsifying properties induced by structural alterations in common carp (Cyprinus carpio) myofibrillar protein during long-term frozen storage

The effect of ultrasound-assisted immersion freezing (UIF), air freezing (AF), and immersion freezing (IF) on the protein structure, aggregation, and emulsifying properties of common carp (Cyprinus carpio) myofibrillar protein during frozen storage were evaluated in the present study. The result showed that, compared with AF and IF samples, UIF sample had higher reactive/total sulfhydryl, protein solubility, and lower protein turbidity (P < 0.05), indicating that UIF was beneficial to inhibit protein oxidation and aggregation induced by frozen storage. UIF inhibited the alteration of secondary structure and tertiary structure during frozen storage. Meanwhile, UIF sample had higher emulsifying activity index, and smaller emulsion droplet diameter than AF and IF samples (P < 0.05), suggesting that UIF was beneficial for maintaining the emulsifying properties of protein during storage. In general, UIF is a potential and effective method to suppress the decrease in protein emulsifying properties during long-term frozen storage.

Soy protein isolate-sodium alginate colloidal particles for improving the stability of high internal phase Pickering emulsions: Effects of mass ratios

The potential of sodium alginate (SA) at different mass ratios to improve the emulsifying ability of soy protein isolate (SPI) in high internal phase Pickering emulsions (HIPPEs) was evaluated in this work. SPI-SA particles were used as a natural particle stabilizer of HIPPEs with 80 % oil phase. The properties of particles with varying SPI to SA ratios (10:0, 10:1, 10:3, 10:5, 10:10, and 10:15 w/w) were evaluated. HIPPEs with a 10:10 SPI to SA ratio exhibited the smallest droplet sizes. Both the storage modulus and loss modulus of the HIPPEs increased with increasing SA addition ratios, implying that HIPPEs with higher SA addition have stronger gel characteristics. In addition, super-resolution microscopy and cryogenic scanning electron microscopy indicated that SA addition strengthened the compactness of the interface film and increased the distribution uniformity of HIPPEs. In conclusion, the combination of SPI and SA is beneficial for improving the performance of HIPPEs.

Evaluation of the Quality Changes in Three Commercial Pastourma Samples during Refrigerated Storage Using Physicochemical, Microbiological, and Image Analyses Combined with Chemometrics

Despite the inherent stability of dried and cured products, such as pastourma, appropriate refrigeration remains essential for preserving their optimal characteristics. This study explored quality and safety characteristics in lamb, beef, and buffalo pastourma during 16-day refrigeration storage after package opening. The comprehensive approach employed Attenuated Total Reflection-Fourier-Transform Infrared (ATR-FTIR) spectroscopy, colorimetry, and image analysis, alongside physicochemical and microbiological analyses, to shed light on these alterations. The findings reveal a reduction in textural uniformity and color vibrancy (fading reds and yellows) across all samples during storage, with lamb pastourma exhibiting the most pronounced effects. Notably, image analysis emerged as a powerful tool, enabling the accurate classification of samples based on storage duration. Additionally, significant variations were observed in moisture content, hue angle, firmness, and TBARS levels, highlighting their influence on pastourma quality. The study documented a gradual decrease in lactic acid bacteria and aerobic plate count populations over time. ATR-FTIR spectra's interpretation revealed the presence of lipids, proteins, carbohydrates, and water. Protein secondary structures, demonstrably influenced by the meat type used, exhibited significant changes during storage, potentially impacting the functional and textural properties of pastourma. Overall, the findings contribute to a deeper understanding of pastourma spoilage during storage, paving the way for the development of improved preservation and storage strategies.

Discrimination among Fresh, Frozen-Stored and Frozen-Thawed Beef Cuts by Hyperspectral Imaging

The detection of the storage state of frozen meat, especially meat frozen-thawed several times, has always been important for food safety inspections. Hyperspectral imaging (HSI) is widely applied to detect the freshness and quality of meat or meat products. This study investigated the feasibility of the low-cost HSI system, combined with the chemometrics method, to classify beef cuts among fresh (F), frozen-stored (F-S), frozen-thawed three times (F-T-3) and frozen-thawed five times (F-T-5). A compact, low-cost HSI system was designed and calibrated for beef sample measurement. The classification model was developed for meat analysis with a method to distinguish fat and muscle, a CARS algorithm to extract the optimal wavelength subset and three classifiers to identify each beef cut among different freezing processes. The results demonstrated that classification models based on feature variables extracted from differentiated tissue spectra achieved better performances, with ACCs of 92.75% for PLS-DA, 97.83% for SVM and 95.03% for BP-ANN. A visualization map was proposed to provide detailed information about the changes in freshness of beef cuts after freeze-thawing. Furthermore, this study demonstrated the potential of implementing a reasonably priced HSI system in the food industry.

Solubilization strategy of myofibrillar proteins in low-ionic media (prototype soup): The effect of high-intensity ultrasound combined with non-covalent or covalent modification of polyphenols on myosin molecular assembly

This study investigated the effect of (-)-Epigallocatechin-3-gallate (EGCG) non-covalent/covalent grafting onto myofibrillar protein (MP) by high-intensity ultrasound (HIU) on its water-solubility and filament forming behavior. The results showed that the introduction of EGCG, especially in the case of covalent grafting, could inhibit the molecular assembly of myosin and improve the MP water solubility from 2.7% to 53.1% (P < 0.05). The HIU pretreatment provided more opportunities for EGCG grafting onto the ultrasound-treated protein (UMP) by disrupting the filamentous polymerization of myosin and thus further facilitated MP dissolution. Additionally, compared with the UMP-EGCG non-covalent complexes, the covalent complexes with a yellow appearance exhibited a higher absolute zeta potential (35.9 mV) and a lower particle size (53.7 μm) (P < 0.05). Overall, the combination of HIU pretreatment and EGCG covalent modification may provide a promising method for improving the solubility and processing properties of MP in low ionic media (prototype soup).

Effects of freeze-thaw cycles on in-vitro digestive properties of myofibrillar protein in mirror carp (Cyprinus carpio L.), based on protein degradation, oxidation, and structural properties

The in-vitro digestive properties of myofibrillar protein (MP) in mirror carp (Cyprinus carpio L.) after freeze-thaw (F-T) cycles were analyzed in terms of the relationship between protein degradation, oxidation, and structural properties. The F-T samples exhibited a significant increase in glucosidase activity, N-acetyl-β-d-glucosidase activity, total protease activity, and non-protein nitrogen content. α-aminoadipate semialdehyde and γ-glutamate semialdehyde contents increased by 23.17% and 123.12%, respectively. Furthermore, 53.97% decrease in the total nitrogen content and changes in the content of different soluble proteins were observed. X-ray diffraction intensity, thermal stability, free amine content, hydrolysis degree, and digestibility of the MP samples decreased, and the 2θ angle and zeta potential were reversed. Besides, changes in the amide band wavenumbers were also detected. Therefore, the protein structure was unfolded and aggregates were formed through degradation and oxidation induced by the F-T cycles, ultimately making the in-vitro digestion of MP difficult.

Myofibril degradation and structural changes in myofibrillar proteins of porcine longissimus muscles during frozen storage

The effect of frozen time and the temperature on myofibril degradation and the structure of myofibrillar proteins of porcine longissimus muscles were investigated. With extended frozen time and increased temperature, the muscle fibres became broken; the muscle cells became irregularly arranged; and the fragmentation index value, number of ionic bonds, and number of hydrogen bonds of the samples significantly decreased. Meanwhile, the myofibril fragmentation index value, number of hydrophobic interactions, and number of disulphide bonds significantly increased (P < 0.05). After 12 months of storage, the intensities of I760/I1003, I850/I830, I1450/I1003, and I2945/I1003 in the samples frozen at -8 °C were reduced by 4.36 %, 1.28 %, 1.86 %, and 0.74 %, respectively. A reduction in the maximum absorption peak and a red shift were observed in the ultraviolet spectrum. Therefore, frozen storage resulted in significant damage to the tissue microstructureand caused accelerated protein degradation, and the loss of protein structural integrity.

Changes in the structure and hydration properties of high-temperature peanut protein induced by cold plasma oxidation

To improve the hydration properties of high-temperature pressed peanut protein isolate (HPPI), we investigated the effect of cold plasma (CP) oxidation on functional and structural properties. Compared to HPPI, the hydrated molecules number and the surface contact angle were significantly decreased at 70 W, from 77.2 × 109 to 17.7 × 109 and from 85.74° to 57.81°, respectively. The reduction of the sulfhydryl content and the increase of the disulfide bond and di-tyrosine content indicated that the structural transformation was affected by the oxidation effect. In terms of structural changes, a stretched tertiary structure, ordered secondary structure, and rough apparent structure were observed after CP treatment. Additionally, the enhancement of surface free energy and group content such as -COOH, -CO and -OH on the surface of HPPI contributed to the formation of hydrated crystal structures. In general, the oxidation effect of CP effectively improved the hydration properties of HPPI and broaden its application field.

Effect of protein structure changes during different power ultrasound thawing on emulsification properties of common carp (Cyprinus carpio) myofibrillar protein

The impact of ultrasound thawing (UT) at different power (0 W, 100 W/0.132 W·cm-2, 300 W/1.077 W·cm-2, and 500 W/1.997 W·cm-2, namely WT, UT-100, UT-300, and UT-500) on protein structure, aggregation, and emulsifying properties of common carp (Cyprinus carpio) myofibrillar protein were investigated in the present study. The result showed that the reactive sulfhydryl content, total sulfhydryl content, protein solubility, and absolute potential of UT-300 samples were obviously higher than those of other thawed samples, while the turbidity of UT-300 samples was lower (P < 0.05), which indicated that proper UT power was beneficial to inhibit protein aggregation caused by thawing, while too low (100 W) or too high (500 W) ultrasonic power had poor effect. The Ca2+-ATPase activity and thermal stability of UT-300 samples were much higher than those of other thawed samples (P < 0.05), indicating that UT-300 inhibited myosin denaturation and thermal stability reduction of thawed products. The α-helix content of UT-300 samples was higher than that of other thawed samples, while the β-sheet content was significantly lower than that of other thawed samples (P < 0.05). The fluorescence intensity of UT-300 samples was higher than that of other thawed samples, and the λmax of UT-300 samples and UT-100 samples were lower than that of other thawed samples, which indicated that UT-300 could effectively inhibit the alteration of protein secondary structure and tertiary structure during thawing. The emulsifying activity of UT-300 samples was significantly higher than that of WT samples, and the droplet diameter of UT-300 samples was also lower than that of WT samples (P < 0.05), which indicated that UT-300 inhibited the decrease of emulsifying property during thawing. Overall, moderate ultrasonic power (300 W) could effectively inhibit the protein aggregation and structural changes during thawing, led to the decrease of emulsifying activity.

Effects of taro [Colocasia esculenta (L.) Schott] slices on nutritional quality, sensory quality, and shelf life of Chinese pickled and steamed pork belly

This study aimed to investigate the influence of different ratios of taro slices (TS) on the nutritional quality, sensory quality, and shelf life of Chinese pickled and steamed pork belly (CPSPB). The study examined various aspects of CPSPB, including its proximate components, fat oxidation, fatty acid composition, protein hydrolysis, oxidation reaction, and induction period (IP). Additionally, the sensory quality and texture analysis were compared simultaneously. The results showed that the addition of TS to CPSPB significantly improved water and lipid loss (p < 0.05), increased the unsaturated/saturated ratio of fatty acids, and reduced lipid and protein oxidation. Additionally, the incorporation of TS extended the IP and enhanced the shelf life of CPSPB. Particularly, the addition of a specific amount of TS (60%) to CPSPB resulted in the highest organoleptic quality. Therefore, these results emphasize the positive impact of TS on the overall quality of CPSPB, highlighting its potential to enhance the nutritional value, sensory attributes, and shelf life.

Changes in, and correlation analysis of, volatile compounds, key enzymes, and fatty acids in lemon juice vesicles during freeze drying and hot-air drying

BACKGROUND

Lemon juice vesicles are distinguished by their unique and abundant volatile flavor compounds, which can undergo complex changes during drying. In this study, integrated freeze drying (IFD), conventional freeze drying (CFD), and hot-air drying (AD) were used to dry lemon juice vesicles to investigate the changes in, and correlations among volatile compounds, fatty acids, and key enzyme activity during the drying process.

RESULTS

Twenty-two volatile compounds were detected during the drying processes. Compared with fresh samples, seven compounds were lost in the dried samples after IFD, seven after CFS, and six after AD, and the loss rates of the total content of volatile compounds in the dried samples were 82.73% in CFD, more than 71.22% in IFD, and more than 28.78% in AD. In total, 1.015 mg/g of seven fatty acids were detected in the fresh samples; the content loss rates of total fatty acids after drying were 67.68% in AD, more than 53.00% in CFD, and more than 36.95% in IFD, respectively. During the three drying processes, IFD retained relatively higher enzyme activity in the samples.

CONCLUSION

Many positive and negative correlations (P < 0.05) were observed among the key enzyme effects, fatty acids, and volatile compounds, showing close associations. The current work provides information that is important for the selection of suitable drying techniques for lemon juice vesicles and suggests how to control their flavor during the drying process. © 2023 Society of Chemical Industry.

Mechanism of low-voltage electrostatic fields on the water-holding capacity in frozen beef steak: Insights from myofilament lattice arrays

This study investigated the impact of low-voltage electrostatic field-assisted freezing on the water-holding capacity of beef steaks. The enhances mechanism of water-holding capacity by electrostatic field was elucidated through the detection of dynamic changes in the myofilament lattice and the construction of an in vitro myosin filaments model. The findings demonstrated that the disorder of the myofilament array, resulted from the aggregation of myosin filaments during freezing, is a crucial factor responsible for the water loss. The intervention of the electrostatic field can effectively reduce the myofibril density by 18.7%, while maintaining a regular lattice array by modulating electrostatic and hydrophobic interactions between myofibrils. Moreover, the electrostatic field significantly inhibited the migration of immobilized water to free water, thus resulting in an increase in the water-holding capacity of myofibrils by 36%. This work provides insights into the underlying mechanisms of water loss in frozen steaks and its regulation.

The inhibition mechanism of nanoparticles-loading bilayer film on texture deterioration of refrigerated carp fillets from the perspective of protein changes and exudates

Herein, the protective pattern of bilayer film on the texture stability of fillets was discussed in terms of endogenous enzyme activity, as well as protein oxidation and degradation. The texture properties of fillets wrapped with nanoparticles (NPs) bilayer film were greatly improved. NPs film delayed protein oxidation by inhibiting the formation of disulfide bond and carbonyl group as evidenced by the increase of α-helix ratio (43.02%) and the decrease of random coil ratio (15.87%). The protein degradation degree of fillets treated with NPs film was lower than that of control group, specifically with a more regular protein structure. The exudates accelerated the degradation of protein, while NPs film effectively absorbed exudates to delay protein degradation. Overall, the active agents in the film were released into the fillets to play an antioxidant and antibacterial roles, and the inner layer of film could absorb exudates, thus maintaining the texture characteristics of fillets.

Effects of carboxymethyl chitosan on the oxidation stability and gel properties of myofibrillar protein from frozen pork patties

The effect of carboxymethyl chitosan (CMCH) on the oxidation stability and gel properties of myofibrillar protein (MP) from frozen pork patties was investigated. The results showed that CMCH could inhibit the denaturation of MP induced by freezing. Compared with the control group, the protein solubility was significantly (P < 0.05) increased, while the carbonyl content, the loss of sulfhydryl groups, and the surface hydrophobicity were decreased, respectively. Meanwhile, the incorporation of CMCH could alleviate the influence of frozen storage on water mobility and reduce the water loss. With the increased concentration of CMCH, the whiteness, strength, and water-holding capacity (WHC) of MP gels were significantly improved, in which the maximum value was at addition level of 1 %. In addition, CMCH inhibited the decrease in the maximum elastic (G') value and loss factor (tan δ) value of samples. By scanning electron microscopy (SEM) observation, CMCH stabilized the microstructure of the gel and maintained the relative integrity of the gel tissue. These findings suggest that CMCH could be used as a cryoprotectant to maintain the structural stability of MP in pork patty during frozen storage.

Comparison of biochemical characteristics and gel properties of chicken myofibrillar protein affected by heme-iron and nonheme-iron oxidizing systems

In this study, the effect of hemin and non-heme iron on the biochemical and gelling properties of chicken myofibrillar protein (MP) was compared. Results revealed that free radicals from hemin incubated MP were significantly higher than that in FeCl₃ incubated samples (P < 0.05), and had higher ability to initiate protein oxidation. The carbonyl content, surface hydrophobicity, random coil increased with oxidant concentration, whereas the total sulfhydryl and α-helix content decreased in both oxidizing systems. The turbidity and particle size were increased after oxidant treatment, indicating oxidation promoted the cross-linking and aggregation of protein, and the degree of aggregation was higher in hemin treated MP compared with that incubated with FeCl₃. The biochemical changes of MP resulted in an uneven and loose gel network structure, which significantly reduced the gel strength and water holding capacity (WHC) of the gel.

Recent innovations and emerging technological advances used to improve quality and process of plant-based milk analogs

The worldwide challenges related to food sustainability are presently more critical than ever before due to the severe consequences of climate change, outbreak of epidemics, and wars. Many consumers are shifting their dietary habits toward consuming more plant-based foods, such as plant milk analogs (PMA) for health, sustainability, and well-being reasons. The PMA market is anticipated to reach US$38 billion within 2024, making them the largest segment in plant-based foods. Nevertheless, using plant matrices to produce PMA has numerous limitations, including, among others, low stability and short shelf life. This review addresses the main obstacles facing quality and safety of PMA formula. Moreover, this literature overview discusses the emerging approaches, e.g., pulsed electric field (PEF), cold atmospheric plasma (CAP), ultrasound (US), ultra-high-pressure homogenization (UHPH), ultraviolet C (UVC) irradiation, ozone (O3), and hurdle technology used in PMA formulations to overcome their common challenges. These emerging technologies have a vast potential at the lab scale to improve physicochemical characteristics, increase stability and extend the shelf-life, decrease food additives, increase nutritional and organoleptic qualities of the end product. Although the PMA fabrication on a large scale using these technologies can be expected in the near future to formulate novel food products that can offer green alternatives to conventional dairy products, further development is still needed for wider commercial applications.

Effects of tea branch liquid smoke on oxidation and structure of myofibrillar protein derived from pork tenderloin during curing

This study focused on how different concentrations of tea branch liquid smoke (TLS) in the curing solution impacted the physicochemical properties and antioxidant properties of pork tenderloin. Five experimental (1.25 mL/kg, 2.5 mL/kg, 5 mL/kg, 10 mL/kg, 20 mL/kg) and blank groups set up over 4 days, and it was found that the physicochemical indexes, antioxidant capacity, thermal stability and protein network structure of the cured meat using 5 mL/kg of liquid smoke were excellent than the other groups used (P < 0.05). However, concentrations at 20 mL/kg accelerated protein oxidation. Low frequency nuclear magnetic resonance (LFNHR) revealed that TLS also improved the water holding capacity of the cured meat by increasing the percentage of bound water. Additionally, the correlation analysis demonstrated that the inoxidizability of myofibrillar protein was significantly related to cooking loss and water distribution, which were adjusted by changing the usage of liquid smoke.

The positive contribution of ultrasound technology in muscle food key processing and its mechanism-a review

Traditional processing methods can no longer meet the demands of consumers for high-quality muscle food. As a green and non-thermal processing technology, ultrasound has the advantage of improving processing efficiency and reducing processing costs. Of these, the positive effect of power ultrasound in the processing of muscle foods is noticeable. Based on the action mechanism of ultrasound, the factors affecting the action of ultrasound are analyzed. On this basis, the effect of ultrasound technology on muscle food quality and its action mechanism and application status in processing operations (freezing-thawing, tenderization, marination, sterilization, drying, and extraction) is discussed. The transient and steady-state effects, mechanical effects, thermal effects, and chemical effects can have an impact on processing operations through complex correlations, such as improving the efficiency of mass and heat transfer. Ultrasound technology has been proven to be valuable in muscle food processing, but inappropriate ultrasound treatment can also have adverse effects on muscle foods. In the future, kinetic models are expected to be an effective tool for investigating the application effects of ultrasound in food processing. Additionally, the combination with other processing technologies can facilitate their intensive application on an industrial level to overcome the disadvantages of using ultrasound technology alone.

Effect of maltodextrin on the oxidative stability of ultrasonically induced soybean oil bodies microcapsules

Introduction

Encapsulation of soybean oil bodies (OBs) using maltodextrin (MD) can improve their stability in different environmental stresses and enhance the transport and storage performance of OBs.

Methods

In this study, the effects of different MD addition ratios [OBs: MD = 1:0, 1:0.5, 1:1, 1:1.5, and 1:2 (v/v)] on the physicochemical properties and oxidative stability of freeze-dried soybean OBs microcapsules were investigated. The effect of ultrasonic power (150–250 W) on the encapsulation effect and structural properties of oil body-maltodextrin (OB-MD) microcapsules were studied.

Results

The addition of MD to OBs decreased the surface oil content and improved the encapsulation efficiency and oxidative stability of OBs. Scanning electron microscopy images revealed that the sonication promoted the adsorption of MD on the surface of OBs, forming a rugged spherical structure. The oil-body-maltodextrin (OB-MD) microcapsules showed a narrower particle size distribution and a lower-potential absolute value at an MD addition ratio of 1:1.5 and ultrasonic power of 250 W (32.1 mV). At this time, MD-encapsulated OBs particles had the highest encapsulation efficiency of 85.3%. Ultrasonic treatment improved encapsulation efficiency of OBs and increased wettability and emulsifying properties of MD. The encapsulation of OBs by MD was improved, and its oxidative stability was enhanced by ultrasound treatment, showing a lower hydrogen peroxide value (3.35 meq peroxide/kg) and thiobarbituric acid value (1.65 μmol/kg).

Discussion

This study showed that the encapsulation of soybean OBs by MD improved the stability of OBs microcapsules and decreased the degree of lipid oxidation during storage. Ultrasonic pretreatment further improved the encapsulation efficiency of MD on soybean OBs, and significantly enhanced its physicochemical properties and oxidative stability.

Insights into the effects of different drying methods on protein oxidation and degradation characteristics of golden pompano (Trachinotus ovatus)

The quality of dried fish products differs based on the drying method employed owing to the different drying principles, with changes in protein affecting the quality of these products. Therefore, we investigated the differences in golden pompano (Trachinotus ovatus) fish tissue structure and protein physicochemical properties under different drying methods. Freeze drying (FD) induced less tissue damage, leaving more intact myofibrils, than that of hot air drying (HAD) and heat pump drying (HPD). The structural stability of myofibrillar protein was retained to a greater extent after FD, while myoglobin oxidation was lower, and fish meat color was well maintained. Our findings not only elucidated the effects of several drying methods on the physicochemical properties of fish protein, but also determined the mechanism underlying quality changes observed during the drying process. This provides a theoretical reference for the study of dried fish filet processing.

Effects of Ultrasound-Assisted Immersion Freezing on the Protein Structure, Physicochemical Properties and Muscle Quality of the Bay Scallop (Argopecten irradians) during Frozen Storage

In this study, the comparison effects of ultrasound-assisted immersion freezing (UIF) at different ultrasonic power, immersion freezing (IF), and air freezing (AF) on the protein thermal stability, protein structure, and physicochemical properties of adductor muscle of scallop (Argopecten irradians) (AMS) during frozen storage were investigated. Principal component analysis and the Taylor diagram were used to comprehensively analyze all the indicators tested. The results showed that the UIF at 150 W (UIF-150) treatment was the most effective way to delay the quality deterioration of AMS during 90-day frozen storage. This was mainly because, compared to AF and IF treatments, UIF-150 treatment more effectively minimized the changes in the primary, secondary and tertiary structures of myofibrillar proteins, and it preserved the protein thermal stability of AMS by producing small and regular ice crystals in the AMS tissue during the freezing process. Moreover, the results of physicochemical properties indicated that UIF-150 treatment significantly inhibited the fat oxidation and microbiological activities of frozen AMS, and it finally maintained the microstructure and texture of AMS during frozen storage. Overall, UIF-150 has potential industrial application prospects in the rapid freezing and quality preservation of scallops.