In order to investigate the effect of cryoprotectant on the freezing preservation of frozen tilapia surimi,goods cryoprotectant(sucrose/sorbitol) and trehalose were added in the tilapia surmi before being frozen.In this artice,the protein freezing denaturation of tilapia surimi during the freezing and frozen process was primary discussed by using gel strength,salt-solubility of myofibrillar protein and Ca2+-ATPase activity as parameters.The results showed that the additive of trehalose compared with goods cryprotectant more effective with preventing the protein freeze denaturation in tilapia surimi during the frozen storage and improve the quality of its products.

对鱼油的提取工艺、鱼油的功能性研究和市场开发进行了综述,鱼油中DHA和EPA含量较高,具有很高的营养价值和很好的开发利用前景。以罗非鱼加工下脚料提取鱼油不仅能提高罗非鱼产品的附加值,而且还能促进罗非鱼养殖加工产业良性发展,具有重要的经济价值和现实意义。

Fish oil was extracted from Tilapia byproduct by hydrolysis,regarding the extraction rate of crude fish oil as the experimental indexes.The optimum Alcalase hydrolysis condition was studied by using orthogonal experiment.The results showed the following optimal conditions:collagen was heated directly for 2 h at pH 7.5 and 55℃by added alcalase enzyme 1 750 U/g of collagen(solid to liquid was 1:2).Under these conditions extraction rate offish oil was 12.56%.the sentry evaluation was carried and the physical and chemical indicators are conducted of fish oil extracted.The results show that the crude fish oil with light fishiness was reddish brown and slightly turbid.Water and volatile matter concentration was 0.42%.The acid value of fish oil extracted was 9.29 mg/g,the peroxide value of fish oil was 8.35 mmol/kg.The iodine value was 135.87 g/(100 g).The impurity content was 0.32%.The physics and chemistry indexes achieved to the second crude fish oil in standard specifications of the aquatic products.

The protoplasts of Aspergillus fumigatus was prepared by dissolving it with mixed-enzyme system.After the protoplasts were induced by ultraviolet ray and LiCl,a high-yield strain UV-26 was obtained by first screening of flat plate and second screening of shake flask.The enzymatic ability of the strain was increased from the initial 1.1 U/mL to 3.4 U/mL.And it can descend stably after six generation.

Chitosanase were immobilized in polyvinyl alcohol(PVA)and sodium alginate carrier system by a freezing-thawing method.The optimal composition of the PVA and sodium alginate was obtained by central composite design and response surface analysis was 10.88% and 1.07%.And the characteristics of free and immobilized enzyme were compared.The immobilization in cryo PVA-gel stabilized the chitosanase and ensured high mechanical and chemical stability of the biocatalyst.Compared with the free enzyme,the optimum pH value and temperature ofimmobilized chitosanase respectively shifted from 5.0 to 4.5 and from 60℃ to 65℃.And immobilization increased in Km value from 7.24mg/mL to 10.12mg/mL.After seven times repeated batch operation,the relative activity ofimmobilized enzyme was about 79%.

为牟取暴利经营者在水发水产品在加工过程中,往往加入国家明令禁止的非食品添加剂改变水发水产品的外观,诱引消费者购买,不仅损害了消费者的利益,对消费者的健康也构成了威胁。水发水产品的主要不合格项为:甲醛超标、重金属超标、pH值过高、双氧水超标,消费者可以通过感官"看、闻、摸、尝"和一些简易的化学方法来鉴别,从而维护自身利益。

对实验室选育的Aspergillus niger CU-1菌株在最佳培养条件下菌体生长与产酶的关系进行测定,在最佳培养条件下,72 h生物量达到最大值,88 h左右α-葡萄糖转苷酶活力达到最高点,溶液pH 5.0有利于α-葡萄糖转苷酶稳定积累;将A.niger CU-1按照10%接种量接入25%木薯淀粉和3%麸皮的转苷反应培养基中,在30℃、160 r/min下培养3.0 d,定时取样检测pH、还原糖、总糖、菌体干重、异麦芽低聚糖(IMO)含量,绘制发酵过程曲线.产物经过HPLC分析,表明主要的有效组分是异麦芽糖、潘糖、异麦芽三糖和异麦芽四糖,还有明显的聚合度为5和6的低聚糖,异麦芽低聚糖含量≥80%,葡萄糖含量约4%.结果表明,高浓度底物和长时间发酵策略,适合于Aspergillus niger CU-1的发酵生产高含量异麦芽低聚糖.