几种天然防腐剂对延长HTST消毒奶保质期的研究

对天然防腐剂对HTST消毒奶的防腐效果进行研究,根据不同防腐剂的性能对添加方法、添加量、防腐效果进行比较,为中小型企业延长HTST消毒奶保质期提供一种科学方法。      

复合天然防腐剂对低温火腿保质期的影响

本文探讨了复合天然防腐剂(nisin、纳他霉素、EDTA-2Na、溶菌酶)对低温火腿保质期的影响。通过正交试验,确定了4种防腐剂的最佳配比。试验结果表明在低温火腿中加入0.30g/kg的nisin,0.2g/kg的纳他霉素,0.15g/kg EDTA-2Na,0.25g/kg溶菌酶的复合防腐剂,保存效果最好,在室温下保质期最长达145d。     

复合天然防腐剂应用于薏苡奶的研究

初步研究了甘草、乌梅、丁香、花椒四种中药材的抑菌作用,分别得出了它们对几种食品污染微生物的最低抑菌浓度及它们与糖的协同抑菌作用。在此基础上,探讨了将复合天然防腐剂应用于薏苡奶的抑菌效果,并优化了复合天然防腐剂的配比。      

复合天然防腐剂应用于薏苡奶的研究

初步研究了甘草、乌梅、丁香、花椒四种中药材的抑菌作用,分别得出了它们对几种食品污染微生物的最低抑菌浓度及它们与糖的协同抑菌作用。在此基础上,探讨了将复合天然防腐剂应用于薏苡奶的抑菌效果,并优化了复合天然防腐剂的配比。     

延长低温火腿肠保质期的nisin复合防腐剂

采用正交试验方案筛选得到ｎｉｓｉｎ为主的复合防腐剂,应用于低温火腿肠中,明显地延长了低温火腿肠在常温下的保质期。结果表明,以Ｎｉｓｉｎ为主的复合防腐剂可以延缓低温火腿肠中的微生物引起的腐败,保质期达到３个月。     

复合防腐剂延长鱼糕保质期研究

为解决传统鱼糕储藏难的问题,研究应用复合防腐剂有效延长鱼糕保质期的方法。通过单因素试验,从6 种防腐剂中选取了Nisin(乳酸链球菌素)、ε- 聚赖氨酸和山梨酸钾3 种对鱼糕腐败菌抑制作用较强的防腐剂;运用响应面法,复配出最优组合复合防腐剂,其配比量为Nisin 质量分数0.023%～0.034%、ε- 聚赖氨酸质量分数0.022%～0.028%、山梨酸钾质量分数0.04%～0.06%。验证实验结果表明,复合防腐剂能有效抑制鱼糕微生物的生长,在0～4℃条件下储藏,鱼糕的保质期可达10 周左右。     

天然防腐剂对真空包装鲜牛肉冷藏条件下保鲜作用的研究

选择植物乳杆菌及其代谢产物和天然物质对在0－4℃贮藏鲜羊内的保鲜效果进行研究,测定不同冷藏期鲜羊肉中挥发性盐基氮、pH值、细菌总数,并进行了感官评定。结果表明,经天然保鲜剂处理的各组样品和保质期均有不同程度的提高。     

几种天然防腐剂的抑菌性能研究

本试验以金黄色葡萄球菌、大肠杆菌、假单胞菌、热死环丝菌为供试验菌,通过滤纸片试验法对常见十种天然防腐剂的抑菌性能进行研究,试验结果显示茶多酚对这四类菌都具有很强的抑菌作用;壳聚糖的抑菌谱也比较宽,但对各菌的抑菌力不如茶多酚强;大蒜对大肠杆菌和金黄色葡萄球菌表现出很强的抑菌作用;溶菌酶、蜂胶和Nisin都主要对G+有较强的抑制作用,而对G-作用弱或无作用;丁香提取液对金黄色葡萄球菌和热死环丝菌的抑菌作用较强;桂皮提取液对金黄色葡萄球菌和大肠杆菌的抑菌作用较强,但对假单胞菌的抑菌作用相对较弱;生姜在试验中未表现出有抑菌作用,迷迭香的抑菌作用也很弱.由此可作为进一步优选几种天然防腐剂复配时的优选依据.     

天然食品防腐剂及其在食品中的应用

天然食品防腐剂来源天然,或从生物体内提取,或其本身为食品的组分.本文简要介绍天然食品防腐剂的抗菌机理,重点阐述几种常用防腐剂的特性及其在食品中的应用和研究现状,以期为其在食品防腐保鲜中的广泛应用提供思路,为提高食品质量提供安全保障.     

不同防腐剂对油酥锅盔保质期的影响

对应用不同浓度纳他霉素（NT）、乳酸链球菌（Nisin）、双乙酸钠（SDA）和脱氢醋酸钠（DHA）处理的油酥锅盔的保质期效果进行了研究。结果表明,不同浓度的防腐剂可不同程度地抑制油酥锅盔表面的茵落生长。最优组合为NT：Nisin=8：2（0．24g/kg：O．04g／kg,保质期为33d）和NT：SDA=7：3（0．21g／kg：1．2g/kg,保质期为33d）,与对照组（保质期为20d）相比,大大延长了保质期。     

Effect of various dairy packaging materials on the shelf life and flavor of pasteurized milk

Milk from three different dairies (each a separate trial: 1, 2, and 3) was standardized to 2% fat and pasteurized at 92.2, 84.0, and 76.4 degrees C (temperatures 1, 2, and 3, respectively) for 25 s and packaged into six different packaging boards, [standard (A) milk boards with standard seam; juice boards with standard (B) and J-bottom (D) seams; barrier boards with standard (C) and J-bottom (E) seams; and foil (F) boards with J-bottom seam], resulting in 18 different treatments. Standard plate count (SPC) was used to test for microbial quality, and taste a panel was employed for flavor acceptability and difference on the milk stored at 6.7 degrees C at 1, 2, 3, and 4 wk. Statistical analysis of taste panel data showed that the flavor of milk samples A2, B2, and D2 deteriorated faster than the blind control (freshly high temperature, short time pasteurized low fat milk processed at 80.6 degrees C for 25 s). The flavor of milk packaged in standard (A) and juice (B and D) boards deteriorated at a faster rate than milk packaged in barrier (C and E) and foil (F) boards. Microbial counts showed that milk samples stored at 6.7 degrees C in trials 2 and 3 produced high SPC at wk 3 (ranges of bacteria in cfu/ml for trial 2: 9.9 x 10(1)-1.8 x 10(6) and trial 3: 2.5 x 10(5)-5.5 x 10(8)). In trial 1, high SPC began at wk 4 (9.9 x 10(1)-5.5 x 10(5) cfu/ml). Milk processed at 76.4 degrees C had the lowest bacterial growth rate, and milk processed at 84.0 degrees C had the highest bacterial growth rate. Different boards had no effects (P > 0.05) on the bacterial growth rates. It appeared that the lower the SPC of the raw milk, the slower the bacterial growth rate after 2 wk of storage. Milk samples stored at 1.7 degrees C maintained low SPC at wk 4, with counts of 0 to 40 cfu/ml for trial 2 and 0 to 200 cfu/ml for trial 3.     

Extension of shelf life of pasteurized trim milk using ultraviolet treatment

The demand for minimally processed foods has increased in the last few years and gains high acceptability among consumers as it has better nutritional value than highly processed foods. Pasteurized milk is minimally processed and consumed largely for its fresh taste and higher nutritional value compared to ultrahigh temperature (UHT) and powdered milk. However, one of the constraints is its limited shelf life under refrigeration, as it cannot retain quality and safety for more than 14 days. Nonthermal technologies can extend the shelf life of milk while using low energy. Ultraviolet (UV-C) is well known to inactivate spores as well as vegetative cells. In this study, it was shown that 2.64 J/ml of UV-C treatment applied on pasteurized trim milk can extend shelf life up to 53 days under refrigeration. This finding was also supported by the inactivation of 3.40 ± 0.14 log of thermoresistant Geobacillus stearothermophilus spores (ATCC 7953) in UHT (or sterilized) trim milk with similar UV-C operating conditions. Therefore, microbial study together with physicochemical properties demonstrated that pasteurization followed by UV-C can enhance the shelf life of trim milk considerably.     

盒装巴氏奶货架期的快速预测

采用阻抗法进行盒装巴氏奶货架期预测,结果表明,巴氏奶货架期与细菌数对数值密切相关,在30℃、6h预培养下加样300,400μL及37℃、6h预培养下加样100－400μL进行阻抗测定,建立回归方程式均可快速准确地进行盒装巴氏奶货架期预测,整个预测过程耗时14－20h.     

Nisin协同CO2在巴氏杀菌乳保鲜中的应用

研究了乳酸链球菌素(Nisin)和CO2对巴氏奶的协同保鲜效果.结果表明:4℃充入浓度为42.87 mmol/L的CO2可贮存9 d,而对照组(普通巴氏奶)只贮存6 d;CO2与Nisin协同作用效果更显著,添加浓度为42.87mmol/L的CO2和400IU/g的Nisin可分别在0,4,28℃贮存18,15和2 d(略超国标),而仅充入42.87 mmol/L的CO2的对照组相应可贮存10,9,1 d.相关产品的感官均可接受.     

几种多酚类物质用于延长花生牛轧糖货架期的对比研究

通过测定55 ℃和45 ℃2个加速破坏温度条件下花生牛轧糖的过氧化值、酸价、菌落总数、大肠菌群4个指标,对比研究苹果多酚、葡萄籽多酚、茶多酚3种天然酚类物质对花生牛轧糖货架期的影响.结果 表明,添加0.04％的3种酚类物质都具有减缓花生牛轧糖过氧化值升高,抑制花生牛轧糖酸价增高,抑制菌落总数和大肠菌群增加的作用;在花生...     

A survey of the quality of extended shelf life (ESL) milk in relation to HTST and UHT milk

Thirty milk samples [high‐temperature short‐time (HTST) milk, extended shelf life (ESL) milk (directly heated, indirectly heated, microfiltered), ultra‐high temperature milk] from 17 German dairies were analysed. Total viable counts of directly or indirectly heated ESL milk were significantly lower than those in microfiltered ESL and HTST milk. Evaluation of indigenous enzyme activity revealed sufficient heat treatments in all milk samples. The manufacturing processes were differentiated by estimating furosine and acid soluble whey proteins. Sensory examinations revealed a preference for HTST heated and microfiltered ESL milk. However, a significant discrimination of drinking milk types was not possible. Vitamin losses were not detected, and concentrations of vitamins in different types of milk were comparable.     

Use of chitosan to prolong mozzarella cheese shelf life

This study was undertaken to evaluate the feasibility of using chitosan, a natural antimicrobial substance, to improve the preservation of a very perishable cheese. The effectiveness of chitosan to inhibit the growth of spoilage microorganisms in Mozzarella cheese was studied during refrigerated storage. A lactic acid/chitosan solution was added directly to the starter used for Mozzarella cheese manufacturing. Mozzarella cheese samples were stored at 4°C for about 10 d and microbial populations as well as the pH were monitored. Results demonstrated that chitosan inhibited the growth of some spoilage microorganisms such as coliforms, whereas it did not influence the growth of other microorganisms, such as Micrococcaceae, and lightly stimulated lactic acid bacteria.     

添加脱脂小麦胚水解物延长肉类制品的货架寿命

香肠中添加一种无苦味、无盐的脱脂小麦胚水解物，可明显延长产品在室温下的货架寿命，在室温条件下经10d的需氧贮藏，添加20％小麦胚水解物的香肠（aw=0.903)，其CFU／g是末添加小麦胚水解物香肠（aw=0.957)的1／5000。感官分析结果显示，两种香肠的差别显著，但可接受性方面差异并不显著。     

Active packaging solution to prolong the shelf life of rocket salad

The best packaging conditions for rocket salad were assessed by subsequent experimental trials. In the first step, a preliminary screening of different packaging materials was performed and two micro‐perforated oriented polypropylene films with different micro‐hole diameters (90 and 110 μm) were selected as best packaging solutions. In the subsequent experimental step, modified headspace conditions were applied without any improvement on product quality. In the last step, the effects of an ethylene adsorbent were analysed. Rocket salad packaged in both films with the ethylene adsorbent recorded a shelf life of about 16 days, compared to the control samples that remained acceptable for 13 days. During storage, the microbial quality (mesophilic and psychrotrophic bacteria, pseudomonadaceae, lactic acid bacteria, yeasts, total coliforms and enterobacteriacae), the pH, the colour changes and the main sensory parameters were also monitored.     

嗜冷菌对牛乳货架期的影响

采用Azocasein法和碱式滴定法对嗜冷茵产蛋白酶和脂肪酶的活力进行了测定.研究了嗜冷茵在原料乳中的生长规律.结果表明,嗜冷茵产蛋白酶和脂肪酶的最佳pH值为7.0,最适培养温度在30℃,产酶高峰分别出现在30 h和24 h,在最适培养条件下嗜冷茵数的动态增加与蛋白酶和脂肪酶活力变化趋势大致相同.原料乳在低温贮藏过程中,嗜冷茵数与蛋白质、脂肪、水分、密度、pH值也存在有数学相关性.