壳聚糖溶液对豆腐保质期的影响

研究不同浓度壳聚糖溶液对豆腐保质期的影响。研究得出:壳聚糖添加量在1%时豆腐的感官评分较高,可在72 h内有效延缓pH降低,降低水分活度至0.78,可抑制大肠杆菌的增长,延长豆腐保质期3 d。     

Effects of mineral oil coating on internal quality of chicken eggs under refrigerated storage

The selected internal qualities (weight loss, Haugh unit, yolk index, and albumen pH) of noncoated and mineral oil‐coated chicken eggs during 15 weeks of storage at 4 °C and/or during 5 weeks of storage at 25 °C were evaluated. Results indicated that, without refrigeration, the noncoated and mineral oil‐coated eggs rapidly changed from AA to C and B grades as measured by Haugh unit, respectively, after 5 weeks of storage. However, the AA quality of the noncoated eggs could be maintained under refrigerated storage (4 °C) for at least 5 weeks. The mineral oil coating and refrigerated storage (4 °C) synergistically minimised weight loss and preserved the albumen and yolk qualities of chicken eggs during a long‐term storage. At 4 °C, the mineral oil‐coated eggs preserved the initial AA grade for at least 15 weeks with l.19% weight loss.     

白藜芦醇和壳聚糖复合生物保鲜剂对冷藏鱿鱼品质的影响

为了降低鱿鱼中甲醛含量和改善鱿鱼的贮藏品质,研究了白藜芦醇和壳聚糖对鱿鱼品质和货架期的影响。实验分为对照组、白藜芦醇组(0.2%)、壳聚糖组(1.0%)、白藜芦醇(0.2%+壳聚糖1.0%)组。鱿鱼在(0±0.5) ℃贮藏20 d。以挥发性盐基氮(TVB-N)、硫代巴比妥酸值(TBA)、硬度、弹性、甲醛含量的变化、菌落总数(TVC)和感官评分作为评价指标,研究其对鱿鱼的保鲜效果。结果表明:相对对照组,白藜芦醇+壳聚糖显著(p<0.05)降低菌落总数、TVB-N、TBA值和甲醛含量,使硬度和弹性下降程度变缓,显著提高感官评分。白藜芦醇+壳聚糖能够改善鱿鱼的品质,抑制微生物的增殖,并减缓脂肪氧化,延长鱿鱼的货架期,可以用于鱿鱼的保鲜。     

壳聚糖季铵盐复合薄荷提取物涂膜对冷藏草鱼片品质变化的影响

目的 研究新型壳聚糖季铵盐复合薄荷提取物涂膜保鲜方法对4℃下冷藏草鱼鱼片品质的影响.方法 设置壳聚糖季铵盐涂膜组、壳聚糖季铵盐复合薄荷提取物涂膜组与空白对照组3组实验,以pH值、离心损失率、色差值、硫代巴比妥酸值、挥发性盐基氮含量、K值、肌原纤维蛋白含量、活性巯基含量、Ca2+-ATP酶活性、菌落总数、感官评价、电子鼻...     

The effect of mincing method on the quality of refrigerated whiting burgers

Different mincing methods in the preparation of refrigerated whiting burgers had a significant effect on the products' quality during storage ( P  < 0.05). The burgers containing pre-cooked mince products (PCMP) had the lowest microbial load with longest sensory shelf life (10 days). Oven drying of dry ingredients with subsequent hygienic practices markedly decreased microbial load in final products, from 5.30 to <1.47 log CFU g⁻¹ for PCMP, 5.80–2.45 log CFU g⁻¹ for washed mince products (WMP), 5.65–2.14 log CFU g⁻¹ for unwashed mince products. The lowest trimethylamine and total volatile basic nitrogen (TVB-N) were observed with WMP reaching 14.7 and 42.03 mg per 100 g, respectively, at the end of storage. The differences in average surface colours of samples with different preparations and different additives were significant after mincing, but decreased after addition of ingredients, and after cooking. This study indicates the possibility of using pre-cooking as a method for formulated fish mince-based products as it had the highest consumer acceptance as well as longer sensory shelf life despite its higher values of trimethylamine and TVB-N compared with WMP.     

Effect of gelatin coating incorporated with cinnamon oil on the quality of fresh rainbow trout in cold storage

Cinnamon essential oil was used in gelatin coatings to maintain the quality of refrigerated rainbow trout fillets over a period of 20 days. Fish fillets were coated with a solution of 4% gelatin incorporated with cinnamon essential oil and then stored in refrigerator (4 ± 1 °C). Coating’s preservative effect was assessed periodically (every 5 days) by microbial analyses (aerobic plate count and psychrotrophic count), chemical determinations (total volatile basic nitrogen, thiobarbituric acid, free fatty acid) and sensory characteristics. When gelatin coating with cinnamon applied to the preservation of trout fillets, a reduction in the growth of total bacteria was observe after 15 days of storage. Fish fillets with gelatin coating containing 1%, 1.5% and 2% v/v cinnamon oil produced significantly lower (P < 0.05) total volatile basic nitrogen then gelatin‐coated fillets and control until 15 days of storage period (35, 22.86, 30.33, 57.76 and 53.26 mg per 100 g of fillet, respectively). The obtained results indicate that gelatin in the form of coating enriched with cinnamon oil is suitable for the preservation of rainbow trout fresh fillets and to efficiently maintain the quality attributes to an acceptable level during storage.     

Effect of chitosan on Bacillus cereus inhibition and quality of cooked rice during storage

Improper cooling of cooked rice at an inappropriate temperature or leaving cooked rice at room temperature can cause food poisoning attributed to Bacillus cereus. Natural food preservative of either squid or crab polymer chitosan solution was added to examine their antibacterial properties against Bacillus cereus in cooked rice during storage at 37 and 4 °C. Both types of chitosan could retard the growth of B. cereus and total aerobic counts in cooked rice stored at 37 °C up to 1 day. In addition, the effect of chitosans on the physical and textural properties of cooked rice during storage was studied. Both chitosans slightly increased the moisture content of cooked rice. However, chitosans had no effect on the whiteness and hardness of cooked rice during storage (P > 0.05). Therefore, both chitosans have a potential to be used as food preservative for cooked rice with no negative effects on rice quality.     

Applications of chitosan for improvement of quality and shelf life of foods: a review

ABSTRACT:  Chitosan is a modified, natural biopolymer derived by deacetylation of chitin, a major component of the shells of crustacean. Recently, chitosan has received increased attention for its commercial applications in the biomedical, food, and chemical industries. Use of chitosan in food industry is readily seen due to its several distinctive biological activities and functional properties. The antimicrobial activity and film-forming property of chitosan make it a potential source of food preservative or coating material of natural origin. This review focuses on the applications of chitosan for improvement of quality and shelf life of various foods from agriculture, poultry, and seafood origin.     

Effects of chitosan coating and storage position on quality and shelf life of eggs

Effects of chitosan coating and storage positions (small-end down, small-end up or horizontal) on internal quality and shelf life of eggs were evaluated during 5 weeks of storage at 25 °C. Compared with noncoated eggs, all chitosan-coated eggs, irrespective of storage positions, had significantly lesser weight loss, higher Haugh units and higher yolk index throughout the storage. Chitosan coating, irrespective of storage positions, extended the egg shelf life by at least 3 weeks at 25 °C compared with noncoated eggs. Noncoated and chitosan-coated eggs placed small-end down tentatively showed better quality than eggs placed small-end up after 3 and 4 weeks of storage. After 5 weeks of storage, storage positions did not significantly affect quality of noncoated and chitosan-coated eggs. There were no notable differences in total amino acid content of the albumen and fatty acid composition of the yolk between noncoated and chitosan-coated eggs after 5 weeks of storage.     

Plasticizer types and coating methods affect quality and shelf life of eggs coated with chitosan

ABSTRACT:  Effects of different plasticizer types (glycerol, propylene glycol, and sorbitol) and coating methods (brushing, dipping, and spraying) on the internal quality and shelf life of chitosan-coated eggs were evaluated during 5 wk of storage at 25 °C. The Haugh unit and yolk index values suggested that chitosan coating, irrespective of the plasticizer types, extended the shelf life of eggs by almost 3 wk at 25 °C compared with noncoated eggs. After 5 wk of storage, plasticizer types did not significantly affect the quality (weight loss, Haugh unit, and yolk index) of chitosan-coated eggs. However, there was an observable trend indicating that use of sorbitol rather than propylene glycol and glycerol as a plasticizer was better in reducing weight loss (whole egg) of chitosan-coated eggs during a 5-wk storage. After a 5-wk storage, there were no significant differences in weight loss and weight of albumen and yolk among chitosan-coated eggs, regardless of the coating methods. However, both brushing and dipping methods yielded chitosan-coated eggs with better yolk (higher yolk index values) and albumen (lower pH) qualities than did the spraying method. During 3 to 5 wk of storage, the Haugh unit values of chitosan-coated eggs by the brushing method were higher than or comparable to those by dipping or spraying. Therefore, coating of eggs with chitosan using sorbitol as a plasticizer and by the brushing method may offer a protective barrier in preserving the internal quality and thus extending shelf life of eggs.     

脆皮鸡柳制作工艺研究

以鸡肉块为主要原料,研究了面粉、玉米淀粉、香辣粉添加比例、腌制时间四个因素对脆皮鸡柳色泽外观、滋味气味、口感滋味以及咀嚼性等品质特性的影响。实验结果表明,当面粉添加比例为60%,玉米淀粉为30%,香辣粉为1.5%,腌制时间为6h时,生产的脆皮鸡柳具有较高的感官品质。     

Combined effect of electrical stimulation, aging time and marination on quality of chicken breast fillet processed under commercial conditions

BACKGROUND: Electrical stimulation (ES) in poultry processing is reported in the literature with varying degrees of effectiveness. Furthermore, the combined effects of ES and polyphosphate marination are not completely known. The objective of this study was to evaluate the combined effect of ES, aging time prior to deboning and phosphate marination on meat quality of broiler breast fillets. RESULTS: The implementation of ES accelerated pH decline in fillets at any aging time studied regardless of marination treatment, but no differences (P > 0.05) were found in pH of fillets deboned without aging. Warner–Bratzler (WB) shear values of ES fillets significantly decreased (P < 0.05) at 2 h of aging whereas WB of non‐ES fillets decreased at 6 h of aging in breast meat, with or without marination. In non‐marinated fillets the ES treatment reduced (P < 0.05) cooking loss in meat aged 0, 2 and 4 h. In marinated fillets the ES treatment decreased cooking loss at 2, 4, 6 and 8 h of aging. CONCLUSION: ES in carcasses aged 2 or 4 h improves tenderness and reduces cooking loss. Marination improves tenderness in both stimulated and non‐stimulated fillets, at all aging times. Copyright © 2012 Society of Chemical Industry     

Physical,antimicrobial and antioxidant properties of starch‐based film containing ethanolic propolis extract

Propolis is a natural product that meets the requirements as functional additive for food packaging due to its antioxidant and antimicrobial activities. In this work, ethanolic propolis extract (EPE) was incorporated in cassava starch films, and characterisations with respect to their microstructure, mechanical properties, water vapour permeability (WVP), moisture sorption kinetics as well as antimicrobial and antioxidant capacities were performed. The results showed that tensile strength was not affected (P > 0.05) by the presence of EPE but Young's modulus decreased about 50% when compared to control films possibly because of EPE plasticiser effect. When 1% EPE was used, changes in moisture sorption properties were detected by a slightly hydrophobic character at films WVP. When extracted from the films, propolis retained its antioxidant activity. The films exhibited antimicrobial activity against Staphylococcus aureus and Escherichia coli even at low EPE concentrations (0.5%) mainly due to its phenolic compounds.     

马铃薯淀粉添加量对真空滚揉调理鸡柳品质的影响

目的 探讨马铃薯淀粉结合真空滚揉腌制技术对调理鸡柳品质特性的影响。方法 通过测定调理鸡柳的出品率、蒸煮损失、水分含量、水分活度、色差、质构特征和剪切力等指标,探究不同马铃薯淀粉添加量（0.5、1.0、1.5、2.0和2.5%,w/w）对真空滚揉腌制调理鸡柳品质特性的影响。结果 随着马铃薯淀粉添加量的增加,调理鸡柳的出品率、嫩度、弹性、回复性、凝聚性、亮度值和红度值显著提高（P < 0.05）。然而,调理鸡柳的水分含量、水分活度、蒸煮损失、硬度则随着淀粉添加量的增加而显著下降（P < 0.05）,黄度值没有显著变化（P > 0.05）。结论 马铃薯淀粉的添加对真空滚揉腌制的调理鸡柳品质特性具有良好的促进作用,且以2.0%为最佳添加量。本研究为更高品质的调理鸡柳的工业生产提供技术支撑。     

壳聚糖/纳米银复合涂膜对鸡蛋的保鲜效果

将橘皮提取液还原制备的纳米银,按照0.5%,1.0%,2.0%的质量分数分别添加到壳聚糖溶液中,制成复合涂膜液,对鸡蛋进行涂膜,分别记为CS/Ag 0.5、CS/Ag 1.0、CS/Ag 2.0,纯壳聚糖涂膜组记为CS。将涂膜组与未处理组(CK1)、清水清洗组(CK2)置于温度25℃、相对湿度70%的条件下贮藏。定期对鸡蛋内容物的外观、失重率、气室高度、相对密度、哈夫单位(HU)、蛋清pH、蛋黄指数(YI)、鸡蛋内容物菌落总数以及蛋壳外表面微观形貌等指标进行测定。结果表明,纳米银在涂膜中的质量分数为1.0%时,涂膜鸡蛋可维持较低的失重率和气室高度,稳定的蛋清pH值,较高的相对密度、哈夫单位和蛋黄指数值。同时,该复合涂膜可显著抑制鸡蛋内容物中微生物的滋生,并能有效维持涂膜结构在贮藏期间的稳定性,从而提高保鲜效果的持续性。因此,CS/Ag 1.0组鸡蛋在25℃时的货架期可长达79d,相较于CS组延长了至少34d,而相较于CK1和CK2则至少延长了69d。     

Inhibition of selected pathogens inoculated on the surface of catfish fillets by high molecular weight chitosan coating

Antibacterial activity of high molecular weight water-soluble (HMWWS) chitosan (800 kDa) was investigated against four Gram-negative (Escherichia coli, Salmonella typhimurium, Vibrio cholerae and Vibrio parahaemolyticus) and two Gram-positive (Staphylococcus aureus and Listeria monocytogenes) bacteria. Catfish fillets were surface-inoculated with these food-borne pathogens and coated with chitosan dissolved in aspartic acid (AS) or acetic acid (AC) solution at different concentrations (1% or 3%). Samples were stored at 4 °C for 8 days, except for those inoculated with Vibrio species (10 °C for 6 days). Overall, the most effective coating treatment was the 3% HMWWS chitosan in AS solution (800AS3%). Compared with the control, significant (P < 0.05) reductions caused by 800AS3% were observed for all tested pathogens at the end of storage. The growth of V. parahaemolyticus was completely suppressed by 800AS3%. This study demonstrated that HMWWS chitosan in AS solution could be used as an alternative antimicrobial coating for catfish fillets.