【作者】 凌萍华；

【导师】 谢晶；

【作者基本信息】 上海海洋大学 ， 食品科学与工程， 2011， 硕士

【摘要】 为了改善南美白对虾黑变快、货架期短的情况,本研究以上海南汇地区所产南美白对虾为研究对象,通过测定贮藏过程中多酚氧化酶活力、感官评价、细菌总数、常规理化指标,研究了冰温、气调包装和保鲜剂等保鲜方法对南美白对虾的保鲜效果。为南美白对虾保鲜加工的规模化,提供一定的理论依据和技术支持。主要研究结果如下:1、冰温贮藏对南美白对虾保鲜效果的影响的研究。通过冻结实验,得知南美白对虾的冰点为-2.2℃。在贮藏的过程中,冰温贮藏组的多酚氧化酶（PPO）活力与黑变、挥发性盐基氮（TVB-N）含量、pH值、菌落总数（TBC）的变化速率均显著低于冷藏方式;冰温贮藏组的感官得分显著高于冷藏组。冰温贮藏的南美白对虾货架期可达8 d,常规冷藏仅为4 d。冰温贮藏作为一种物理保鲜方法,能显著减缓南美白对虾品质下降速度,延长货架期,而且无需添加保鲜剂,避免了食品安全性问题,在实际应用中具有潜在推广价值。2、南美白对虾气调包装工艺及保鲜效果评价。采用高阻隔包装材料K-PET/PE复合袋,对南美白对虾进行气调包装,（4±1）℃冷藏。通过测定各处理组的综合感官评定分、色差L*值、色差b*值、pH值、菌落总数、挥发性盐基氮等指标评价保鲜效果,实验结果表明:85% CO₂ / 5% O₂/10% N₂和40% CO₂/30% O₂/30% N₂两种气调包装的保鲜效果最佳,使南美白对虾的冷藏货架期延长至12天。3、4-己基间苯二酚（ 4-hexylresorcinol , 4-HR ） +1%壳聚糖（A组）、0.01%4-HR+1%壳聚糖（B组）和0.05%4-HR+1%壳聚糖（C组）在冷藏条件下对生鲜南美白对虾黑变的抑制作用的研究。测定了南美白对虾的理化指标和4-HR的残留量。结果表明:在整个贮藏过程中,C组一直具有最低的多酚氧化酶活性和最低的黑变感官评分,但是在第4天4-HR的残留量已经超过了1mg/kg;A组和B组在4天内黑变感官评分和酚酶活性无显著差异（P>0.05）,两组4-HR的残留量分别在第8天和第6天超过1mg/kg,根据TBC、TVB-N的变化可知A、B、C三组的货架期分别为6天、6天和8天,而对照组1只有4天。一定浓度的4-HR与壳聚糖复配保鲜不仅能高效且安全地减缓南美白对虾黑变进程,而且能延长货架期。4、冰温技术结合保鲜剂对南美白对虾品质影响的研究。通过正交试验确定黑变抑制组分（M）,使用黑变抑制组分（M）及1%的壳聚糖处理南美白对虾,进行冰温贮藏。结果表明: M保鲜剂配方为0.01% 4-己基间苯二酚+1.5%柠檬酸+1%抗坏血酸,冰温贮藏能显著减缓TVB-N值、pH值和TBC值增加速度,M配方保鲜剂能有效抑制虾的多酚氧化酶活性和黑变,冰温技术结合M配方保鲜剂保藏南美白对虾能互补二者优缺点,能显著减低黑变感官得分,PPO活性、TVB-N、pH值和TBC的增长速度。比（4±1）℃冷藏的货架期延长近1倍。冰温技术结合保鲜剂能有效防止虾类黑变和延长品质货架期。5、涂膜及气调保鲜对南美白对虾品质影响的研究。使用黑变抑制组分（M）和1%壳聚糖（Chitosan）的复合保鲜剂,结合气调保鲜南美白对虾,气调采用高阻隔复合包装袋（ K-PET/PE ）,使用40%CO₂/30%O₂/30%N₂ （Ⅰ）和85%CO₂/5%O₂/ 10%N₂（Ⅱ）2种气调包装,（4±1）℃冷藏。组合（Chitosan+Ⅰ）、（Chitosan+M+Ⅰ）、（Chitosan+Ⅱ）、（Chitosan+M+Ⅱ）分别在第6天、第8天、第12天和第14天开始出现显著黑变;相比对照组,所有处理组在整个贮藏期内的菌落总数、挥发性盐基氮、pH值、多酚氧化酶的活性的增长速度均有所下降,组合（Chitosan+M+Ⅱ）保鲜效果最佳,使（4±1）℃条件下的货架期延长约2倍。涂膜保鲜剂结合气调包装（MAP）的处理方式是南美白对虾保鲜的有效手段,具有应用推广价值。6、气调包装结合冰温贮藏对南美白对虾品质影响的研究。对南美白对虾实施（85%CO₂/5%O₂/10% N₂）的气调包装,并且进行冰温贮藏（通过冻结试验以及温度波动情况确定冰温贮藏温度）。结果表明:对照组的货架期为4天,冰温组的为8天,气调包装组为12天,气调结合冰温组为16天。气调包装和冰温技术具有明显的协同效应,两者的结合使用可有效防止虾类黑变和延长虾的品质货架期。更多还原

【Abstract】 In order to inhibit melanosis of Pacific white shrimp（Litopenaeus vannamei） and prolong their shelf-life, Pacific white shrimp（Litopenaeus vannamei）cultivated in Nanhui District, Shanghai were selected and they were treated respectively with super-chilling, modified atmosphere packaging, preservative and differet combinations of these methods. Polyphenol oxidase （PPO） activity, sensory evaluation,total bacterial count and other physical indexs were determined to evaluate the effects of the different preservation methods on shrimps. The research datas can provide some theoretical and technical support for processing of pacific white shrimp. The results were gotten as follows:1、Effects of super-chilling on preservation of pacific white Shrimp were studied. Based on the freezing experiments, the ice point of Pacific white shrimp was -2.2℃, Magnitude of changes of sensory evaluation score, PPO actives, melanosis, TVB-N, pH, TBC of the treated were rather less than those of the controlled. The shelf-life of the treatment was 8 days, while the shelf-life of the controlled was only 4 days. The super-chilling technolgy which was a safe physical preservation method with out preservative which can prolong the shelf-life and delay the quality losses of Pacific white shrimp obciously, It was valuable to extensively popularize the super-chilling method on preservation of Pacific White Shrimp in the light of its safeties and effects.2、The techniques and freshness keeping effect of modified atmosphere packaging （MAP） of the different combinations proportion of CO₂, O₂ and N₂ on Pacific white shrimp were studied. Shrimps were modified atmosphere packaged with the K-PET/PE bags of the high-barrier compound packaging materials, then all groups were preserved at 4℃. The sensory evaluation, L* value, b* value, pH, total bacterial count （TBC） and total volatile basic nitrogen （TVB-N） were examined to assess freshness-keeping effects of all groups. The results showed that the freshness keeping effects of 85% CO₂/5% O₂/10% N₂ and 40% CO₂/30% O₂/30% N₂ were the best of all, they obviously extended the shelf-life of Pacific white shrimp at the cold storage to 12 days.3、Melanosis inhibition of 0.002% 4-HR with 1% chitosan （Group A）, 0.01% 4-HR with 1% chitosan （Group B） and 0.05% 4-HR with 1% chitosan （Group C） on Pacific white shrimp were examined under cold store. The changes of sensory evaluation of melanosi（sMSE）, polyphenol oxidase （PPO）, total bacterial count （TBC） and total volatile basic nitrogen （TVB-N） of shrimp were determined, the residual levels of 4-hexylresorcinol（RLOHR）was also detected. The results showed that the values of PPO and MSE of Group C were the lowest compared with the others throughout the storage process, but the RLOHR of Group C had exceeded 1 mg / kg on on the 4^th day, The PPO and MSE of Group A and Group B were no significant difference （P>0.05） on the 4^th day, but the time of RLOHR of two groups exceeded 1 mg / kg was the 4^th and 6^th day, respectively. According to TBC and TVB-N values, the shelf life of A, B and C were 6 days, 6 days and 8 days, respectively. The shelf life of the controlled was only 4 days. A certain concentration of 4-HR combined with chitosan can not only delay the melanosis safely and effectively, but also extend the shelf-life.4、Effects of super-chilling combined with preservatives on melanosis and qualities of Pacific white shrimps were examed. The results showed that the temperature of super-chilling ranged from 0 to -2.2℃, and the temperature fluctuation of a common refrigerator met the requirements of super-chilling. The formulation was optimized using orthogonal array design. A blend containing 0.01% 4-hexylresorcinol, 1.5% citric acid and 1% ascorbic acid provided an optimal inhibitory effect against the darkening of Pacific white shrimps and could effectively inactivate PPO activity. Super-chilling could make the growth of TVBN,pH and TBC slow down significantly. The combination of super-chilling with the optimized blend gave a mutual complement between them, presented a more significant inhibitory effect against the darkening of Pacific white shrimps and the growth of PPO activity, TVB-N, pH and TBC, and resulted in a 2-fold prolongation of shelf-life when compared with cold storage at （4±1）℃. These results showed that super-chilling provides a promising technique for delaying the darkening and prolonging the shelf-life of Pacific white shrimp.5、Effects of film-forming combined with modified atmosphere packaging on qualities of Pacific white shrimp were studied. 1% chitosan was combined with a kind of mixed anti-melanosis component （M） to prevent corrosion of Pacific white shrimp under modified atmosphere packaging （MAP） of two gas mixtures （40% CO₂ /30% O₂ /30% N₂ （Ⅰ） and 85% CO₂ /5% O₂ /10% N₂ （Ⅱ） ）with high-barrier packaging bag （K-PET/PE） at （4±1）℃. The mixed anti-melanosis component （M） were optimized by orthogonal experiment, the optimal combination was as follows, 0.01% 4-hexylresorcinol+1.5% citric acid+1% ascorbic acid, the Group （Chitosan+Ⅰ）, （Chitosan+M+Ⅰ）, （Chitosan+Ⅱ） and （Chitosan+M+Ⅱ） began to generate melanosis dramatically at 6th, 8th, 12th and 14th day, respectively; all treatment groups, compared with the control, could slow down the increase of TBC, TVB-N, PPO activity and the pH significantly during the whole storage period. The fresh-keeping effect of Group （Chitosan + M +Ⅱ） was the best in all groups, extending the shelf-life of Pacific white shrimp more than two times compared with that of the control when stored at （4±1）℃. Film-forming combined with modified atmosphere packaging is an effective preservation method for Pacific white shrimp, which has application values.6、The effects of modified atmosphere packaging （MPA） combined with Super-chilling on pacific white shrimp were studied. The shrimps were treated with modified atmosphere packaged （85%CO₂/5%O₂/10% N₂） and were preserved at the super-chilling temperature （confirmed by the freezing experiment and temperature fluctuation of refrigerator）. The shelf-life of the control, the group MAP, the group super-chilling and the group MAP plus super-chilling was respectively 4days, 8days, 12days and 16days.MAP and super-chilling have a extraordinarily collaborative effects, MAP plus super-chilling can strikingly delay the melanosis and extend shelf-life of Pacific White Shrimp.更多还原