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A new repeated freeze-thaw extraction was employed to extract crude polysaccharide from Ganoderma lucidum, named as GLPf, in order to improve its extraction yield and bioactivity. Single-factor tests and response surface experiment were used to obtain the optimal extraction conditions. Three novel G. lucidum polysaccharide fractions (GLPf30, GLPf60, and GLPf80) were isolated and purified from GLPf by stepwise alcohol precipitation. Results showed that the optimal parameters were as follows: Swelling ratio 1:14 (g/mL), free-ze-thaw time 140 min, and free-ze-thaw times was 3. Under these conditions, its extraction rate was 2.71%, which was significantly higher than that of polysaccharide extrcted by traditional water extraction (GLP, 2.36%). The preliminary structural features of all polysaccharide fractions were determined by highperformance anion-exchange chromatography with pulsed-amperometric detection (HPAEC-PAD) and Fourier transform infrared spectrophotometer (FT-IR) analyses, which showed that all sugar fractions were acidic polysaccharides, and they all were composed of six monosaccharides (fucose, glucosamine, galactose, glucose, xylose and mannose) with pyranose as the backbone. However, there were significant differences in both monosaccharide composition and physicochemical property, and GLPf30 had the highest percentage of GlcN (up to 37.66%). The results of antioxidant activity assays showed that antioxidant power of GLPf30 was significantly higher than that of the other two polysaccharides (GLPf60 and GLPf80) and their precursors GLPf. These findings would provide scientific basis for the rational development and high value utilization of G. lucidum polysaccharides.

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Summary: The fraudulent practice of beef adulteration is a growing concern, as it violates consumer rights. Electrical impedance spectroscopy (EIS) combined with machine learning has emerged as a widely used approach to identify low‐quality meat. Unlike traditional biochemical methods that require expensive instruments, complex sample preparation, and chemical reagents, EIS is a cost‐effective alternative. However, EIS data are susceptible to temperature fluctuations, requiring a waiting period under consistent temperature conditions for data stabilisation before measurements. This process becomes impractical when dealing with a large number of samples. To overcome this limitation, standardisation, normalisation, and smoothing methods were introduced in the meat quality detection based on EIS data. A recognition model for detecting carrageenan adulteration in beef was established. Under an inconsistent temperature condition, by applying the spectra pre‐processing methods to the prediction dataset, the model accuracy reached 84%, whereas the accuracy of the unprocessed prediction dataset dropped to 54%. This study demonstrates that acquiring EIS data under consistent temperature conditions is unnecessary if proper spectra pre‐processing methods are applied. By eliminating the waiting time for data stabilisation, this practical approach enhances the efficiency and accuracy of meat quality detection. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of FI (Fraction I, molecular weight < 1 kDa), which is separated from natural whey protein, on the antioxidant activity, sensory quality, color, texture characteristics, and microbial growth of pork balls during repeated freeze–thaw cycles (F-T cycles). The results indicated that pork balls mixed with FI significantly improved in quality after repeating the F-T cycle, especially with the addition of 10% FI. The quality was improved significantly after repeated F-T cycles by adding 10% FI, and the antioxidant activity after seven F-T cycles decreased by 40.78%, a similar result to that obtained with the addition of 0.02% BHA. In addition, FI effectively reduced the sensory damage of pork balls caused by repeated freezing–thawing and also significantly inhibited the growth of microorganisms. In summary, FI not only has excellent antioxidant capacity under repeated freeze–thaw conditions but also has significant antibacterial and quality preservation effects and is expected to be quantified as a kind of natural food additive with antibacterial and antioxidant properties. This paper not only explores the effect of FI on the quality characteristics of frozen and thawed pork balls in prepared dishes but also provides a theoretical basis for the application of whey polypeptides in prepared meat. [ABSTRACT FROM AUTHOR]

Whey protein hydrolysate (WPH) has made a breakthrough in inhibiting oxidative deterioration and improving the quality of meat products during storage. Based on our previous study of extracting the most antioxidant active fraction I (FI, the molecular weight < 1 kDa) from whey protein hydrolysates of different molecular weights, the present study continued to delve into the effects of WPH with fraction I on the structure and function of myofibrillar proteins (MP) in ground pork during the freeze–thaw (F-T) cycles. With the number of F-T cycles raised, the total sulfhydryl content, the relative contents of α-helix, Ca2+-ATPase activity, K+-ATPase activity, solubility, emulsion activity index (EAI), and emulsion stability index (ESI) of MP gradually decreased. Conversely, the carbonyl content and the relative content of random curl showed an increasing trend. In particular, the damage to the structure and the function of MP became more pronounced after three F-T cycles. But, during F-T cycles, FI stabilized the structure of MP. Compared to the control group, the 10% FI group showed a remarkable improvement (p < 0.05) in the total sulfhydryl content, Ca2+-ATPase activity, K+-ATPase activity, solubility, EAI and ESI after multiple F-T cycles, suggesting that 10% FI could effectively inhibit protein oxidation and had the influence of preserving MP function properties. In conclusion, WPH with fraction I can be used as a potential natural antioxidant peptide for maintaining the quality of frozen processed meat products. [ABSTRACT FROM AUTHOR]

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The freeze-tolerant anuran Dryophytes chrysoscelis, Cope's gray treefrog, mobilizes a complex cryoprotectant system that includes glycerol, glucose, and urea to minimize damage induced by freezing and thawing of up to 65% of body water. In this species' eastern Northern American temperate habitat, oscillations of temperature above and below freezing are common; however, the effects of repeated freezing and thawing in this species are unstudied. The biochemical and physiological effects of repeated freeze-thaw cycles were therefore evaluated and compared with cold acclimation and single freeze-thaw episodes. Glycerol was elevated in plasma, liver, and skeletal muscle of both singly and repeatedly frozen and thawed animals compared with cold-acclimated frogs. In contrast, urea was unchanged by freezing and thawing, whereas glucose was elevated in singly frozen and thawed animals but was reduced toward cold acclimation levels after repeated bouts of freezing. Overall, the cryoprotectant system was maintained, but not further elevated, in all tissues assayed in repeatedly frozen and thawed animals. For repeated freeze-thaw only, hepatic glycogen was depleted and plasma hemoglobin, indicative of erythrocyte hemolysis, increased. Postfreeze recovery of locomotor function, including limb and whole body movement, was delayed with repeated freeze-thaw and was associated with glycerol accumulation and glycogen depletion. Individuals that resumed locomotor function more quickly also accumulated greater cryoinjury. Integrated analyses of cryoprotectant and cryoinjury accumulation suggest that winter survival of D. chrysoscelis may be vulnerable to climate change, limited by carbohydrate stores, cellular repair mechanisms, and plasticity of the cryoprotectant system. [ABSTRACT FROM AUTHOR]

In order to study the effects of freezing-thawing times on the quality characteristics of frozen mutton. After freezing and thawing repeatedly for 0, 1, 3, 5 times and then refrigerated at 4 ℃ for 1, 3, 5, 7 days, the nutritional quality, edible quality, texture characteristics and lipid oxidation degree of Oula Tibetan mutton were determined. The results showed that with the increase of freeze-thaw times, the nutritional quality of Tibetan mutton deteriorated significantly, the moisture content and protein content decreased significantly (P < 0.05); The overall eating quality of Tibetan mutton decreased significantly, especially after 5 freeze-thaw cycles, the color stability and water holding capacity decreased significantly (P < 0.05), the tenderness decreased slightly, but the change was not significant, and the meat hardness and chewiness decreased, while the viscosity, elasticity and adhesiveness increased; Meanwhile, peroxide value (POV) and thiobarbituric acid value (TBARS) reached the maximum after 5 freeze-thaw cycles (P < 0.05), indicating that the degree of lipid oxidation increased with the increase of freeze-thaw cycles; At the same time, the longer the cold storage time, the worse the meat quality. The above results showed that the increase of freeze-thaw cycles had a great impact on the meat quality, and the repeated freeze-thaw phenomenon should be avoided in the actual production, processing and transportation of meat.

Repeated freeze-thaw cycles are among the main causes of quality deterioration in frozen oysters. Here, we focused on changes in texture, pH, moisture distribution, salt-soluble protein content, secondary structure, sulfhydryl (-SH), malondialdehyde (MDA), and Ca2+-ATPase activity of Pacific oysters (Crassostrea gigas) after each freeze-thaw cycle for five cycles. The protein and fat content of C. gigas deteriorated, and the content of salt-soluble protein decreased significantly in the first three freeze-thaw cycles. MDA and -SH levels decreased significantly in the first two freeze-thaw cycles (P < 0.05), and Ca2+-ATPase decreased significantly in the first three cycles (P < 0.05). Therefore, the number of freeze-thaw cycles of C. gigas should be reduced to the greatest possible extent during freezing and storage, and it would be better to limit the cycle to one time to preserve the quality of C. gigas. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of FI (Fraction I, molecular weight < 1 kDa), which is separated from natural whey protein, on the antioxidant activity, sensory quality, color, texture characteristics, and microbial growth of pork balls during repeated freeze–thaw cycles (F-T cycles). The results indicated that pork balls mixed with FI significantly improved in quality after repeating the F-T cycle, especially with the addition of 10% FI. The quality was improved significantly after repeated F-T cycles by adding 10% FI, and the antioxidant activity after seven F-T cycles decreased by 40.78%, a similar result to that obtained with the addition of 0.02% BHA. In addition, FI effectively reduced the sensory damage of pork balls caused by repeated freezing–thawing and also significantly inhibited the growth of microorganisms. In summary, FI not only has excellent antioxidant capacity under repeated freeze–thaw conditions but also has significant antibacterial and quality preservation effects and is expected to be quantified as a kind of natural food additive with antibacterial and antioxidant properties. This paper not only explores the effect of FI on the quality characteristics of frozen and thawed pork balls in prepared dishes but also provides a theoretical basis for the application of whey polypeptides in prepared meat.

Whey protein hydrolysate (WPH) has made a breakthrough in inhibiting oxidative deterioration and improving the quality of meat products during storage. Based on our previous study of extracting the most antioxidant active fraction I (FI, the molecular weight < 1 kDa) from whey protein hydrolysates of different molecular weights, the present study continued to delve into the effects of WPH with fraction I on the structure and function of myofibrillar proteins (MP) in ground pork during the freeze–thaw (F-T) cycles. With the number of F-T cycles raised, the total sulfhydryl content, the relative contents of α-helix, Ca2+-ATPase activity, K+-ATPase activity, solubility, emulsion activity index (EAI), and emulsion stability index (ESI) of MP gradually decreased. Conversely, the carbonyl content and the relative content of random curl showed an increasing trend. In particular, the damage to the structure and the function of MP became more pronounced after three F-T cycles. But, during F-T cycles, FI stabilized the structure of MP. Compared to the control group, the 10% FI group showed a remarkable improvement (p < 0.05) in the total sulfhydryl content, Ca2+-ATPase activity, K+-ATPase activity, solubility, EAI and ESI after multiple F-T cycles, suggesting that 10% FI could effectively inhibit protein oxidation and had the influence of preserving MP function properties. In conclusion, WPH with fraction I can be used as a potential natural antioxidant peptide for maintaining the quality of frozen processed meat products.

Repeated freeze-thaw (FT) cycles damage the quality of frozen starch-based foods and accelerate the digestion rate of starch. This study investigated how potato soluble dietary fiber (PSDF) affects the physicochemical characteristics and digestibility of potato starch (PS) after repeated FT cycles. Results indicated that repeated FT cycles of potato starch resulted in the enlargement of gel pores, an increase in hardness (from 322.5 g to 579.5 g), and a decrease in gel porosity, leading to reduced water-holding capacity (from 94.2 % to 85.4 %). However, the addition of PSDF stabilized the 3D structure of the PS/PSDF gel, with minimal fluctuations in hardness (413.0–447.5 g) and water-holding capacity (94.4–93.6 %). Meanwhile, PSDF enhanced intramolecular hydrogen bonding within starch molecules and promoted molecular interactions, increasing the PS/PSDF gel's helix structure; therefore, PSDF effectively addressed the increase in rapidly digestible starch caused by repeated FT cycles. Furthermore, PSDF might attach to the surface of starch particles, so limiting starch granule expansion and decreasing the peak viscosity increase caused by repeated FT cycles. The findings suggest that PSDF could be an effective component for improving the quality of potato starch-based frozen food. • PSDF could aid repeated FT-treated PS to form a more uniform gel structure. • PSDF reduced fluctuations in hardness and WHC of gel made by repeated FT-treated PS. • PSDF effectively solved the increase in starch digestion rate caused by repeated FT. • PSDF can be an effective component the quality of frozen potato starch-based food. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

One of the major concerns with WMA is degradation due to the presence of moisture during production. In the field, moisture in the aggregates may not be completely expelled due to a lower production temperature which increases the potential for moisture damage, including stripping. The objectives of this paper are: (1) to investigate the impact of hydrated lime on the moisture resistance of WMA mixtures prepared using saturated surface dried (SSD) moist aggregates; (2) to examine the effects of multiple freeze–thaw cycles on the moisture susceptibility of WMA mixtures. Testing samples were prepared in the laboratory with the materials from a local asphalt plant in Michigan according to the Superpave mix design. The control samples (HMA) were mixed and compacted at 165 °C and 155 °C, respectively. The WMA samples were prepared using different additives, which were Advera, Sasobit, Cecabase RT, and water as a foaming agent. For the moisture susceptibility evaluation, the mixtures were prepared using SSD aggregates and the WMA mixtures were both mixed and compacted at a similar temperature, 130 °C. Hydrated lime was added as an anti-stripping agent to determine whether or not it can improve the moisture susceptibility of the HMA and WMA prepared using SSD moist aggregate. The samples for the multiple freeze–thaw study were prepared according to a similar mix design at numerous temperatures (100 °C, 115 °C and 130 °C) and different percentages of WMA additives based on the specific ranges recommended by the manufacturer of each WMA technology. Each additive was added to the asphalt binder prior to mixing with aggregate based on the designated percentage. Based on the results, the presence of hydrated lime in the WMA has resulted in the TSR values passing the minimum requirement of 0.80. This indicates that by adding hydrated lime, the moisture susceptibility of the WMA can be improved. The WMA samples that were tested under multiple freeze–thaw cycles do not perform as well as the HMA samples. Different additives perform better at different quantities in the mixture, as well as at different temperatures. Lower mixing and compaction temperatures negatively affect the TSR after repeated freeze–thaw conditions. [ABSTRACT FROM AUTHOR]