Use of Cryoprotectants to Stabilize Functional Properties of Prerigor Salted Beef During Frozen Storage

Changes in functional properties (gelforming ability, water-holding capacity, and protein solubility) of salted prerigor beef and postrigor beef were measured over 6 months frozen storage at ?28°C, as affected by addition of 5.6% cryoprotectants [Polydextrose® or a mixture (1:1) of sucrose and sorbitol]. Addition of NaCl to comminuted muscle prior to freezing accelerated destabilization of muscle proteins with respect to functional properties. This effect was reduced by cryoprotectants; most effectively by sucrose/sorbitol and only slightly less effectively by polydextrose. As evidenced by the parameters investigated, quality of prerigor salted muscle treated with cryoprotectants and stored 6 months was approximately equal to that of untreated postrigor meat prior to freezing.     

Functional Stability of Antioxidant-washed, Cryoprotectant-treated Beef Heart Surimi During Frozen Storage

Beef heart surimi was prepared in the presence or absence of propyl gal late and blended with or without cryoprotectants (sorbitol, sucrose) prior to frozen storage at 15°, 29°, and 70°C up to 52 wk. Protein solubility, gelling characteristics, water-holding capacity, cooking yield, and emulsifying properties decreased during storage at 15° and 29°C for control surimi (without cryoprotectants). Propyl gallate alone did not influence functionality changes. However, functional properties were largely protected by cryoprotectants as well as at 70°C independent of cryoprotectants. Thus, unless extremely low temperatures are used, beef heart surimi subjected to long-term cryogenic storage should be mixed with cryoprotectants and antioxidants to preserve functionality.     

Cryoprotectants improve physical and chemical properties of frozen blue crab meat (Callinectes sapidus)

The storage stability of cryogenically frozen crab meat treated with cryoprotectants was compared with pasteurised and water-treated frozen samples to determine changes in physical and chemical properties. Commercially processed, hand-picked blue crab meat was treated with solutions of polydextrose, sucrose + sorbitol/sodium tripolyphosphate or water, vacuum packaged, and cryogenically frozen prior to storage at ?29°C. All treatments were compared with an untreated reference control stored at ?65°C and a pasteurised sample stored at 1.1°C. Samples were evaluated for physical and chemical changes at 4-week intervals over 32 weeks of storage. Cryoprotectants improved oxidative stability, drip loss, expressible moisture, texture, and colour compared to untreated reference and pasteurised samples.     

Application of Antifreeze Protein for Food Preservation: Effect of Type III Antifreeze Protein for Preservation of Gel-forming of Frozen and Chilled Actomyosin

Type III antifreeze protein (AFP) remarkably preserved Ca²⁺ ATPase activity of actomyosin during frozen and chilled storage. Under frozen conditions, AFP helped to retain the Ca²⁺ ATPase activity of actomyosin much higher than that of conventional cryoprotectants (sucrose‐sorbitol mixture). The Ca²⁺ ATPase activity increased with increasing AFP concentration and reached a maximum at 50g/L AFP. After 3‐d chilled storage, the Ca²⁺ ATPase activity of control and sucrose‐sorbitol samples had lost 80% and 50%, respectively, while the AFP samples remained unchanged. A Type III AFP mechanism based on freezing temperature depression (more unfrozen water) and inhibition of ice recrystallization that protects against the freezing of muscle proteins in chilled or frozen conditions is proposed.     

Cryoprotectant Effects during Short Time Frozen Storage of Chicken Myofibrillar Protein Isolates

The purpose of our study was to determine whether stabilization of myofibrillar protein isolates (MPI) during frozen storage could be achieved by addition of certain cryoprotectants. For 2–4 wk at - 21°C MPI were exposed to different freezing and thawing treatments to also determine to what extent cryoprotectants may prevent denaturation of MPI. Overall evaluation of color, weight losses of gels during cooking as well as texture proved that 2.8% sorbitol in combination with 4% starch was the best cryoprotectant. A positive effect was also noted for a mixture of 2.8% sorbitol and 4% sucrose. In contrast, the addition of a dextrose polymer mixture to MPI was not effective in maintaining product integrity.     

Studies on the role of gelatin as a cryo- and lyo-protectant in the stability of capsicum oleoresin nanocapsules in gelatin matrix

The purpose of this study was to determine the effect of freezing process in the absence or presence of excipients on the stability of capsicum loaded nanocapsules (NC) during freeze-thawing and freeze-drying procedures. Capsicum loaded nanocapsules were prepared by the modified-emulsion-diffusion method combined with the microfluidization method. The prepared samples were frozen at freezing temperatures of −40, −20, and −15 °C to study the effects of cooling temperature on the properties of the capsicum oleoresin loaded nanoparticles. From results, a relatively high freezing temperature had an effect on the maintenance of nanocapsule size after freeze-thawing and freeze-drying. Regarding the addition of excipients, gelatin and κ-carrageenan played roles as cryoprotectants and lyoprotectants, and represented R values of 1.01 and 1.13 in size comparisons before and after treatment, respectively. Furthermore, the morphologies of NC made with gelatin or κ-carrageenan were conserved after freeze-drying showing spherical forms according to electron microscope observations.     

EFFECTS OF CRYOPROTECTANTS IN MINIMIZING PHYSICOCHEMICAL CHANGES OF BOVINE NATURAL ACTOMYOSIN DURING FROZEN STORAGE1

Physicochemical changes in bovine natural actomyosin extracted from prerigor semimembranosus muscle were investigated during frozen storage at ?28°C as affected by the addition of cryoprotectants (5.6% Polydextrose® or 5.6% mixture (1:1) of sucrose and sorbitol). Proteins were destabilized during freezing and frozen storage as reflected by decreases in protein solubility, the visual appearance of aggregates in protein sols, decrease in intensity of flow birefringence, intrinsic viscosity and ATPase activity, and changes in size, shape, or charge of the protein (especially myosin) as evidenced by nondenaturing electrophoresis. These effects were reduced to some extent by the two cryoprotectant treatments.     

Cryoprotective effects of trehalose and sodium lactate on tilapia (Sarotherodon nilotica) surimi during frozen storage

The cryoprotective effects of trehalose and sodium lactate at level of 8% (w/w) in tilapia surimi were studied in comparison with a conventional cryoprotectant (sucrose/sorbitol, 1:1) during extended storage at −18 °C for up to 24 weeks. All present cryoprotectants retarded the protein changes as evidenced by the lowered decrease in salt extractable protein (SEP), Ca²⁺-ATPase activity, total sulfhydryl content as well as the impeded increase in disulfide bond content and surface hydrophobicity. The gel-forming ability of frozen surimi was more retained with addition of cryoprotectants. Among all cryoprotectants used, trehalose exhibited the greatest protective effect on protein denaturation as shown by the effectiveness in maintaining Ca²⁺-ATPase activity and protein solubility. Additionally, the greatest breaking force and deformation were obtained in surimi added with 8% trehalose throughout the frozen storage up to 24 weeks. Sodium lactate showed a similar cryoprotective effect to sucrose/sorbitol blend. Therefore, trehalose and sodium lactate appeared to be promising alternative cryoprotectants for surimi owing to their low sweetness and caloric value.     

提高冷冻鸡肉丸食用品质的复合抗冻剂配方优化

为缓解冷冻贮藏对冷冻鸡肉丸食用品质的影响,拟得到"低甜、低热"且经济适用的复合抗冻剂。选择海藻糖和聚葡萄糖与传统商业抗冻剂(蔗糖和山梨醇)混合进行L_9(3~4)正交试验,并测定了解冻汁液流失率、总压出汁液损失率和质构特性等指标。结果表明:冷冻鸡肉丸中复合抗冻剂的最佳添加量(质量分数)为:海藻糖1.0%、聚葡萄糖4.0%、蔗糖3.0%和山梨醇2.0%。在冷冻鸡肉丸中添加该复合抗冻剂,可以有效地提高其保水性和质构特性。     

Cryostabilization of Functional Properties of Pre-Rigor and Post-rigor Beef by Dextrose Polymer and/or Phosphates

Cryostabilization of functional properties of pre-rigor and post-rigor beef throughout 5 mo frozen storage was investigated as affected by the addition of 8% neutralized high molecular weight dextrose polymer (polydextrose), alone or in combination with 0.5% phosphates (a 1:l mixture of sodium tripolyphosphate and tetrasodium pyrophos-phate). Pre-rigor meat to which polydextrose had been added prior to freezing was nearly equivalent in functional properties after 5 mo frozen storage to fresh, pre-rigor meat. Addition of the same level of phosphates plus polydextrose to nontreated muscle (control) after 5 mo frozen storage resulted in higher values for most measured indices of functionality. The effect was almost totally attributable to addition of the phosphates. However, addition of phosphate did not appear to increase the protein cryoprotective effect.     

Cryopreservation of competent intact yeast cells for efficient electroporation

We have developed a simple method for cryopreserving Schizosaccharomyces pombe and Saccharomyces cerevisiae competent intact cells that permits high transformation efficiency and long-term storage for electroporation. Transformation efficiency is significantly decreased if intact cells are frozen in common permeating cryoprotectants such as glycerol or dimethyl sulphoxide. On the other hand, we found that a high transformation efficiency could be maintained if the cells were frozen in a non-permeating cryoprotectant such as sorbitol. The optimum concentration of sorbitol was found in a hypertonic solution of around 2 M. It was also very important to use S. pombe cells grown in minimal medium and S. cerevisiae cells grown in nutrient medium in the exponential growth phase. A slow freezing rate of 10 degrees C/min and a rapid thawing rate of 200 degrees C/min resulted in the highest transformation efficiency. We also found it necessary to wash the thawed cells with 1.0 M of non-electrolyte sorbitol, since the intracellular electrolytes had leaked as a result of cryoinjury. The frozen competent cells stored at -80 degrees C could be used for more than 9 months without any loss of transformation efficiency. This cryopreservation method for electroporation is simple and useful for routine transformations of intact cells. Frozen competent cells offer the advantages of long-term storage with high efficiency and freedom from the preparation of fresh competent cells for each transformation.     

Effect of Sucrose Addition on the Sugar and Sorbitol Composition of Frozen Sweet Cherries and Their Derived Concentrates

Glucose, fructose, sucrose, and sorbitol contents of Van and Black Republican varieties of sweet cherries were determined by high performance liquid chromatography (HPLC) and enzymic analytical procedures. Samples analyzed included frozen fruit, fruit packed as 3.6 parts fruit plus 1 part added sucrose, and cherry juice concentrates derived from the sugar-packed fruit. Cherry fruit showed invert patterns of glucose and fructose and contained trace amounts of sucrose, and 2.6—3.9g sorbitol/100g. Sucrose was either not detected or found in trace amounts in samples to which sucrose had been added. There is evidence that sucrose hydrolysis was caused by presence of invertase. The percent sorbitol content could be used to detect addition of sucrose. Results for sugar and sorbitol content as determined by HPLC or enzymic methods were very similar.     

Cryoprotection Affects Physiochemical Attributes of Rainbow Trout Fillets

ABSTRACT: Stabilization of trout myofibrillar proteins during −20°C, 90-d storage and after soaking fillets in water, 8.0% sucrose/sorbitol, or 1.0% sodium lactate was investigated with or without 0.5% phosphate and with or without 0.05% MgCl₂. Fillets not soaked were the control. Compared with the control, cryoprotectants increased total protein and myofibrillar protein solubility; decreased surface hydrophobicity, total, free, and disulfide sulfhydryl content, and myosin susceptibility to thermal denaturation. There were no differences in total protein solubility and actin susceptibility to thermal denaturation between cryoprotectants and the water treatment. Phosphate minimized frozen storage effects on actin solubility and reduced protein surface hydrophobicity and myosin susceptibility to thermal denaturation, while MgCl₂ increased the negative effects of frozen storage.     

Rheological properties of washed and unwashed tilapia (<Emphasis Type="Italic">Oreochromis mossambicus</Emphasis>) fish meat: effect of sucrose and sorbitol

In the present study, the dynamic viscoelastic behavior (DVB) and flow behavior of fresh tilapia (Oreochromis mossambicus) meat containing cryoprotectants were evaluated with and without water washing. The DVB profile of washed meat with 4% sucrose and sorbitol indicated the maximum structure buildup reaction up to 56.8 °C; thereafter, hydrophobic interactions leading to decreased gelation were suppressed. In both the samples, there was no clear indication of the sol–gel transition temperature. In flow-profile measurements, the presence of cryoprotectants gave rise to the minimum thixotropic area, indicating a low level of impairment in structure. The shear-stress sweep of water-washed tilapia proteins added with cryoprotectants did not reveal significant changes at 28 and 40 °C. In texture-profile analysis, the hardness values were lower in fresh meat than cooked meat. The findings of this study will be helpful in the formulation and design of various mince-based products and in determining the appropriate use of cryoprotectants and water washing in the processing of minced meat.     

Textural Changes and Functional Properties of Cod Mince Proteins as Affected by Kidney Tissue and Cryoprotectants

The addition of cryoprotectants, e.g., a mixture of sucrose and sorbitol or polydextrose (PDT) with sodium hexametaphosphate (SHMP), to improve the texture and water retention properties of cod mince with kidney tissue (modified mince) was studied at ?47°C. Kidney tissue provided trimethylamine oxide (TMAO) demethylase to accelerate dimethylamine (DMA) and formaldehyde formation. Expressible moisture (EM), water uptake ability (WUA), protein solubility, cook loss, DMA production, and textural profile analysis were determined to detect changes in modified mince during frozen storage. Modified mince with SHMP and sucrose/sorbitol or PDT at ?14°C had improved EM, WUA, and cook loss and was more tender.     

两种抗冻剂对罗非鱼鱼糜的凝胶性及抗冻性的影响

以凝胶性能、盐溶性蛋白含量及肌原纤维蛋白Ca2+-ATPase活性的变化为指标,研究了商业抗冻剂(蔗糖/山梨醇)和海藻糖在罗非鱼鱼糜冻藏过程中对蛋白质变性的影响。结果表明,冷藏20周后,添加8%商业抗冻剂和8%海藻糖组鱼糜的破断强度分别比对照高出39.14%和601.11%,凹陷强度分别比对照高出34.14%和39.85%,凝胶强度分别比对照高出36.03%和41.05%,盐溶性蛋白含量分别比对照高出30.00%和38.86%,肌原纤维蛋白Ca2+-ATPase活性分别为下降了67.12%和57.89%,而对照的肌原纤维蛋白Ca2+-ATPase没有活性。结论:添加8%海藻糖比8%商业抗冻剂更能有效抑制罗非鱼鱼糜在冻藏过程中的蛋白质变性,减缓凝胶强度的降低,提高鱼糜制品的质量。     

Cryoprotectants for frozen red meats

This present research explores the sensory characteristics of several cryoprotectant carbohydrates that could be added to frozen red meat. The cryoprotectants were sucrose, dsorbitol, maltodextrin DE 24-38 and synthetic polydextrose. The sweetness of aqueous solutions of sorbitol, maltodextrin and polydextrose was compared to standard 0.8% sucrose solution. The relationship between sweetness and cryoprotectant concentration was determined by a sensory panel using the calibration method. The recognition thresholds of cryoprotectants were determined in aqueous solutions and in beef and pork meat by the staircase method. The time course of the sweetness sensation was evaluated in aqueous sucrose, sorbitol, maltodextrin and polydextrose solutions at concentrations corresponding to the concentration of equal sweetness. The data suggest that polydextrose is the cryoprotectant of choice in red meat. Polydextrose was the least sweet; its taste was distinctly suppressed by meat, the duration of sweetness was the shortest one and the total flavour impact, i.e. the total area under the time-intensity curve, was smallest.     

巨大芽孢杆菌NCT-2冻干菌剂的制备及冻干保护剂响应面优化

采用真空冷冻干燥法制备巨大芽孢杆菌NCT-2菌剂,采用单因素实验并用响应面方法对冻干保护剂配方进行了优化。以巨大芽孢杆菌NCT-2冻干存活率为考察因素,从离心浓缩条件、保护基质、保护剂筛选与复配、复水种类等方面探究影响。结果表明,离心条件为5000 r/min,10 min,选取新鲜培养基为保护基质时对巨大芽胞杆菌NCT-2冻干保护效果最佳。不同复水水质对菌体存活率无较大影响。当冻干保护剂浓度为:蔗糖4.51 mg/g、海藻糖0.90 mg/g、葡萄糖9.60 mg/g时冻干存活率最高,经验证存活率最高可达91.8%。      

Effect of oleic acid on the viability of different freeze-dried Lactiplantibacillus plantarum strains

Freeze drying is one of the most convenient ways to preserve microorganisms, but in the freeze-drying process, strains will inevitably suffer varying degrees of damage under different conditions. The deterioration of cell membrane integrity is one of the main forms of damage. The type and ratio of fatty acids in the cell membrane affect its characteristics. Therefore, it is worth investigating whether certain fatty acids can increase freeze-drying resistance. In this study, we found that adding a low concentration of oleic acid to a cryoprotectant could increase survival rate of strains of Lactiplantibacillus plantarum following freeze drying, and the optimal concentration of oleic acid was determined to be 0.001%. When 0.001% oleic acid was added to phosphate-buffered saline, the freeze-drying survival rate of L. plantarum increased by up to 6.63 times. Adding 0.001% oleic acid to sorbitol, the survival rate of L. plantarum increased by as much as 3.65 times. The 0.001% oleic acid–sucrose cryoprotectant resulted in a freeze-drying survival rate of L. plantarum of about 90%, a 2.26-fold improvement compared with sucrose alone. Although the effect of oleic acid depends on the cryoprotectants used and the strain treated, addition of oleic acid showed significant improvement overall. Further experiments showed that adding a low concentration of oleic acid to the cryoprotectants improved the freeze-drying survival rate of L. plantarum by maintaining cell membrane integrity and lactate dehydrogenase activity. Our findings provide a new strategy for safeguarding bacterial viability in commonly used cryoprotectants by the addition of a common food ingredient, which may be extensively applied in the food industry.     

Freezing Points of Bulking Agents Used in Manufacture of Low-Calorie Frozen Desserts

Freezing points of solutions of polydextrose, polydextrose partially neutralized with potassium hydroxide, sorbitol, and microcrystalline cellulose at concentrations commonly used in frozen desserts were compared with those of similar concentrations of sucrose. Solutions of polydextrose and polydextrose partially neutralized with potassium hydroxide exhibited higher freezing points. Freezing points of sorbitol solutions were lower and microcrystalline cellulose had no measurable effect on freezing point. Most bulking agents affect freezing points; thus, addition to frozen dessert mixes must be regulated carefully.