豆腐保质期研究进展

豆腐是中国的传统食品,豆腐的保质期短是限制其工业化发展的关键因素.为解决此问题,本文从影响豆腐保质期的微生物种类及来源和延长豆腐保质期的杀菌抑菌措施几方面综述了国内外对豆腐保质期的研究进展,同时展望了豆腐保质期研究的新方向.     

天然防腐剂在豆腐中的应用研究

为了保证豆腐产品的食用安全,研究了天然食品防腐剂对豆腐感官质量和保质期的影响。采用天然食品防腐剂壳聚糖、牡蛎壳粉和乳酸链球菌素(Nisin)应用于豆腐保鲜,以菌落总数和感官评价作为考核指标,通过单因子的豆腐保鲜试验和正交试验,筛选了3种保鲜剂的最佳复配比例。结果表明,壳聚糖、牡蛎壳粉、Nisin复配比例分别为1.50%、0.10%、0.10%时的豆腐产品,在20℃条件下保存5天,菌落总数≤105cfu/g,感官上保持了豆腐原有的色泽、香味、风味和质地结构,切面平整光滑,产品符合国家标准要求。     

可食性壳聚糖复合涂膜对干豆腐货架期的影响

壳聚糖是一种理想的防腐涂层材料,主要探索可食性壳聚糖复合涂膜的最适配方,以及可食性壳聚糖复合涂膜延长干豆腐货架期的效果。采用可食性壳聚糖涂膜剂对干豆腐进行保鲜处理,通过单因素试验和正交试验对干豆腐涂膜进行配方和工艺的优化。在常温下以干豆腐样品的感官评价、菌落总数为衡量指标,确定干豆腐涂膜的保鲜效果。通过正交试验设计和验证试验确定干豆腐最佳涂膜保鲜配方和工艺:壳聚糖添加量为1.6%、柠檬酸添加量为1.5%、乳酸链球菌素(Nisin)添加量为0.04%、氯化钙添加量为0.8%、甘油添加量为1.0%,在80℃下涂膜2 min,并对涂膜处理后的干豆腐进行保鲜密封包装。在常温条件下,普通包装保质期达到4 d。     

壳聚糖在加压内酯豆腐加工中的应用研究

利用壳聚糖的增稠、凝胶和防腐作用性质,将其应用于加压内酯豆腐生产过程中。于添加壳聚糖前后,比较加压内酯豆腐相关性质,如失水性、保水性和贮藏性的变化情况。通过正交实验设计得到加压内酯豆腐的最佳生产工艺参数为:生豆浆浓度比为1:12,凝固剂葡萄糖酸内酯(GDL)用量为生豆浆质量的0.20%,壳聚糖用量为生豆浆质量的0.01%,点脑保温为70℃,凝固时间为30min。在该条件下生产出的加压内酯豆腐具有较好的持水性和水分含量,在5℃下保质期为21d,29.4℃条件下可保鲜24h。     

茶多酚、壳聚糖、乳清蛋白复配保鲜剂对干豆腐保鲜效果的影响

目的 研究茶多酚、壳聚糖和乳清蛋白为复配保鲜剂对干豆腐保鲜效果的影响。方法 以茶多酚、壳聚糖和乳清蛋白为原料制备4种复配保鲜剂,在无菌条件下,将干豆腐分切成10 cm边长的正方形,每份样品均匀喷洒5 mL复配保鲜剂,干豆腐叠摞层数为4层, 4℃低温保存条件下,以感官特征、理化指标、微生物指标等方面来评价复配保鲜剂对豆腐的保鲜效果。结果 0.3%茶多酚-0.6%壳聚糖-0.3%乳清蛋白复配保鲜剂对干豆腐的保鲜效果最好,保鲜的干豆腐感官评分最高,能显著延缓干豆腐的挥发性盐基氮、pH、水分流失率、脂肪酸氧化,可有效抑制干豆腐中微生物的生长,从而降低干豆腐腐败变质速度,可将干豆腐的货架期延长至8 d。结论 茶多酚、壳聚糖和乳清蛋白复配保鲜剂安全、营养价值高,对干豆腐具有良好的保鲜效果。     

豆腐保鲜研究进展

豆腐具有很高的营养价值,但是因其蛋白质、脂肪、糖类等物质含量丰富,且水分多,导致微生物滋生,豆腐极易腐败变质,阻碍豆腐行业的发展。通过分析引起豆腐腐败变质的细菌,总结从物理方法、生物方法等方面延长豆腐的保质期的方法,并对豆腐保鲜的发展方向进行展望,旨在为探索和研究延长豆腐保质期的技术方法提供借鉴和参考。     

采用低温等离子体处理对豆腐保鲜效果的影响

以新鲜豆腐为原料,采用低温等离子体处理,以处理电压、时间及豆腐厚度为试验因素,以豆腐表面菌落总数及豆腐质构特性为指标进行响应面试验,建立回归模型并优化工艺参数,分析交互作用对豆腐保鲜效果的影响。研究结果表明：低温等离子体处理的电压、时间和豆腐厚度与豆腐表面菌落总数降低对数值的回归模型显著（P<0.05）,失拟项不显著（P> 0.05）,模型可用于分析和预测等离子体处理对豆腐保鲜效果的影响。低温等离子体处理豆腐最优工艺参数为：处理电压73.66 kV,处理时间4.51 min,豆腐厚度2.94 cm。在最优参数条件下,豆腐表面菌落总数降低对数值预测值为2.603 2 lg(CFU/g);低温等离子体处理对豆腐质构特性等影响均不显著（CV<0.05）,豆腐保持良好的品质特性。说明采用低温等离子体处理新鲜豆腐能有效抑制豆腐表面微生物的生长繁殖,降低豆腐表面微生物数量,且可实现带包装杀菌,这在一定程度上减少豆腐在转运或包装过程中的污染,延长了豆腐保质期。该成果可为豆腐保鲜技术研究开发提供一定参考。     

壳聚糖延长高水分含量番薯果脯保质期的研究

目的:为生产低糖、高水分含量番薯果脯;方法:研究果脯中水分含量与水分活度的关系及细菌总数和霉菌数在保温试验中的变化,并采用不同黏均分子量的壳聚糖降低果脯的水分活度;结果:果脯中霉菌数是影响产品保质期的主要微生物指标,壳聚糖的黏均分子量越低,降低水分活度的幅度越大;结论:通过添加0.5%、9kD黏均分子量的壳聚糖,产品水分含量为20%、总糖为26%时,番薯果脯常温放置保值期达到12个月.     

油煎豆腐饼加工工艺的研究

在实地调查、收集扬州民间豆腐饼配方的基础上,将扬州豆腐饼与各种文献记载的豆腐丸子进行比较研究,研制出优化的工艺配方。研究其熟制工艺,使色泽更为均匀。对主副料比例进行分组研究,使产品口感更为酥松鲜美,结构更加致密,并便于包装和堆垛。比较其低温、速冻、辐照和化学保鲜的效果,筛选出成本低、品质好、保质期满足销售要求的适用保鲜技术。     

新型天然豆腐凝固剂的研究

选用壳聚糖和乙酸作为复合凝固剂,对壳聚糖的絮凝性能进行了初步研究,确定最佳凝固剂的配方。结果表明,壳聚糖保健豆腐的最佳凝固剂配方为壳聚糖浓度1.0%、乙酸溶液浓度1.2%,点浆温度为90 ℃,蹲脑时间为30 min。     

Preparation of tofu using chitosan as a coagulant for improved shelf-life

The potential of chitosan as a coagulant in commercial tofu preparation was investigated with six chitosans of different molecular weights using various treatments. The following optimum processing conditions for tofu preparation were proposed: chitosan with a molecular weight of 28 kDa; chitosan solution type, 1% chitosan/1% acetic acid; chitosan solution to soymilk ratio, 1 : 8; coagulation temperature, 80 °C; coagulation time, 15 min. However, the sensory quality of tofu was notably improved using a 1 : 1 mixture of 1% acetic acid and 1% lactic acid instead of 1% acetic acid alone as a chitosan solvent. Tofu prepared with chitosan had lower ash and higher protein content than those of commercial products tested. In storage tests, the chitosan‐tofu had a longer shelf‐life, about 3 days, than tofu made with CaCl₂. This added shelf‐life is significant in view of the magnitude (366 000 tonnes year^?1) of tofu produced from commercial tofu plants (1407 plants as of 1998) in Korea.     

壳低聚糖作为豆腐凝固剂研究进展

豆腐凝固剂主要有传统盐卤和熟石膏,及近年发展应用葡萄糖酸内酯,但现有凝固剂制成豆腐货架期均较短;壳低聚糖能使大豆蛋白发生胶凝,具有较强抑菌作用,能有效延长豆腐货架期。该文综述壳低聚糖作为豆腐凝固剂研究进展,分析壳低聚糖替代现有豆腐凝固剂优势及存在难点。     

南方臭豆腐的研究现状及加工研究进展

对臭豆腐卤水中微生物及挥发性风味物质构成,安全性问题的研究现状进行综述,阐述臭豆腐生产新工艺的研究现状并探讨下一步研究对策和方向。对臭豆腐生产的标准化进行规范,提高产品产率,减少食用安全性风险,延长产品货架期。为更好的开发及改进臭豆腐工业化生产上提供理论依据。     

Evaluation of physico-chemical characteristics and microstructure of tofu containing high viscosity chitosan

Tofu, containing high viscosity chitosan dissolved in a δ-gluconolactone solution, was prepared and physico-chemical properties, microstructure, textural properties and sensory characteristics were investigated. Moisture content and pH of the chitosan tofu were slightly lower than those of the control tofu. The textural properties of tofu such as hardness, cohesiveness, gumminess and chewiness measured by an instrumental method were not significantly changed by the addition of chitosan to tofu. Springiness of chitosan tofu, however, was significantly higher than that of the control tofu. All characteristics except the roasted nutty aroma and yellowness in the sensory evaluation, did not exhibit significant differences between the chitosan tofu and control tofu. Therefore, the quality of tofu was little affected by the addition of the chitosan content employed in this experiment.     

EVALUATION OF MICROBIOLOGICAL, PHYSICOCHEMICAL AND SENSORY QUALITIES OF CHITOSAN TOFU DURING STORAGE

Tofu containing both low and high viscosity chitosan was prepared and changes in the microbiological, physicochemical and sensory properties of the tofu during storage were investigated. The colony forming units of mesophilic and psychrotrophic microorganisms in tofu containing high viscosity chitosan were markedly lower during storage than those in the control tofu as well as the tofu containing low viscosity chitosan. The _pH of the tofu samples increased during storage. The L and a values of the tofu, especially the control tofu, increased during storage. In the sensory test, the roasted nutty and beany aromas of the tofu decreased during storage. Instrumental analysis of hardness and chewiness of the tofu decreased during storage. Overall preference for the tofu gradually decreased during storage, but overall preference for the tofu containing high viscosity chitosan scored higher than the other tofu samples.     

The effect of oyster shell powder on the extension of the shelf life of tofu

The effects of oyster shell powder addition (0%, 0.05%, 0.1% and 0.2% of soy milk) on quality and shelf life of tofu (soybean curd) were investigated. Yield and moisture of tofu prepared with 0.1% of shell powder were higher than that coagulated with a single use of MgCl₂. Syneresis was low when shell powder was added to tofu, but higher when MgCl₂ was added. Shell powder addition (0.05% and 0.2% of soymilk) showed a high level in hardness and gumminess comparing with tofu prepared with a single use of MgCl₂. However, there was no significant difference (p > 0.05) between 0.05% and 0.2% addition of shell powder. When 0.05% of shell powder was added, overall acceptability showed a high score because tofu had a good mouthfeel, moderate firmness and lower beany-flavour. However, there was not a significant difference (p > 0.05) between no addition and 0.05% and 0.1% addition of shell powder. Tofu prepared with shell powder (0.05% and 0.1% addition) had a shelf life of above 2 days longer than that prepared with a single use of MgCl₂. The addition of shell powder (0.05% and 0.1%) for tofu manufacturing resulted in a good sensory evaluation and the extension of shelf life.     

非发酵型臭豆腐变红现象的抑制

非发酵型臭豆腐在销售贮存过程中会出现表皮变红的腐败现象,从其中分离得到1株红色细菌(CR),对其从物理、化学及生物控制三个方面进行了研究。结果表明,当双乙酸钠浓度为1.0 g/kg、丁香提取液浓度为0.07 g/mL、4℃保存或真空包装的条件下,该腐败菌的生长均可得到有效抑制。结合生产实际,同时向卤中添加1.0 g/kg双乙酸钠和0.07 g/mL丁香提取液,可将臭豆腐在常温(30℃)的保质期延长至48 h,从而有效地控制非发酵型臭豆腐在储藏期出现的变红现象。     

Effect of Chitosan Film Coating Combined with Orange Peel Essential Oil on the Shelf Life of Deepwater Pink Shrimp

In this study, effect of chitosan films combined with orange (Citrus sinensis (L.) Osbeck) peel essential oil on the shelf life of deepwater pink shrimp (Parapenaeus longirostris Lucas 1846) was aimed. Chitosan (CH) and 2% orange peel essential oil (OPEO) combinated chitosan (CH+OPEO) were used for preparing film forming solution. Thickness and microstructure of the films, nutritional composition, sensory and melanosis evaluation, chemical, physical, and microbiological analyses were performed periodically and shelf-life was performed during the storage period of 15 days. The combination of chitosan film with OPEO was effective in prolonging the shelf life of fresh shrimps to 15 days (CH+OPEO), whereas the only chitosan-coated group had a shelf life of 10 days (CH) and the samples packaged without chitosan film had a shelf life of 7 days (control). The results of the study suggested that edible chitosan coatings together with OPEO preserved the shrimps and maintained the shelf life throughout the refrigerated storage period.     

壳聚糖结合1- 甲基环丙烯处理对李果实货架期品质的影响

为改善贮藏后李果实品质和开发综合贮藏保鲜技术,研究贮藏前壳聚糖涂膜处理及其结合贮藏后1- 甲基环丙烯(1-MCP)熏蒸处理对货架期“牛心”李果实品质的影响。结果表明：贮藏前采用10、15、20g/L 壳聚糖溶液涂膜处理及其结合贮藏后采用1.0μl/L 1-MCP 熏蒸可以有效保持低温贮藏(2℃、4 周)后货架期(23～25℃)李果实的硬度,延缓果实VC 含量的下降和果皮色泽的转红,抑制果实腐烂的发生。壳聚糖和1-MCP 的结合处理比两者各自的处理效果都好,能进一步显著地改善李果实在货架期的品质表现,为李果实综合贮藏保鲜技术开发提供依据。     

茶多酚结合壳聚糖对冷却肉的保鲜效果

为了延长冷却肉的货架期,文中采用不同浓度茶多酚结合壳聚糖与可食性膜溶液混合制成涂膜保鲜剂,通过测定贮存过程中冷却肉的细菌总数、挥发性盐基氮(TVB-N值)、pH值、色差值、硫代巴比妥酸值(TBA值)等指标的变化,对冷却肉保鲜效果进行研究。结果表明:0.7%茶多酚、1.0%壳聚糖涂膜保鲜冷却肉效果较好,显著优于对照组和单纯使用壳聚糖涂膜保鲜组,在0～4℃条件下能将冷却肉保鲜期延长至16 d以上。