Water absorption and oxygen barrier characteristics of ethylene vinyl alcohol films

Oxygen transmission rates (OTR) of two multilayer films containing ethylene vinyl alcohol (EVOH) were analyzed after water absorption at 121 °C. The films, referred to as film A and film B, were laminated film of PET/EVOH/PP and coextruded film of PET/PP/nylon 6/EVOH/nylon 6/PP, respectively. OTR increased with water absorption for both films. Graphical representation of data revealed two apparent linear regions describing the change of OTR with water absorption for both films. At low water contents (up to 4%) OTR were similar for the two films but differed dramatically at higher water contents. Water sorption characteristics of two monolayer EVOH barrier films (biaxially oriented and non-oriented) were determined at 25 °C using standard gravimetric method. Moisture sorption isotherms were analyzed using the Guggenheim-Anderson-de Boer model and the cluster theory of Zimm and Lundberg to evaluate the interactions between water and EVOH.     

牛蛙软罐头加工工艺

采用腊肉与卤制品生产工艺相结合的方法，制成具有浓郁香味，肉质致密的牛蛙软罐头。介绍了其制作的加工工艺及配方。     

软包装米饭、面条罐头自加热效果的影响因子研究

通过在不同条件下软包装米饭或面条罐头的自加热实验,找出了影响加热效果的诸因子。实验结果表明,环境温度、软包装米饭或面条罐头的中心初温、水分含量、回生度、厚度以及加热片的重量等因子对加热效果有明显影响,而罐头的真空度没有明显影响。在室温条件下,使用相同重量的单片加热片或双片加热片,其加热效果没有显著性差异,但在5℃环境温度下,其加热效果差异显著。     

耐蒸煮软包装用聚氨酯胶黏剂的研制

耐蒸煮软包装用聚氨酯胶黏剂应用于制备需高温杀菌蒸煮的食品包装袋.为了满足耐蒸煮要求,提高胶黏剂的耐高温性、耐水解性,对胶黏剂的分子结构进行设计.通过环氧树脂与聚氨酯形成互穿网络结构,并在分子链中引入噁唑烷酮基团,提高了热稳定性;硅烷偶联剂的加入,提高了耐湿热粘接强度;所得胶黏剂与性能完全超过GB/F 10004-1998耐蒸煮复合膜、袋的要求(PA/CPP蒸煮前剥离力≥5.0N/15mm,蒸煮后剥离力≥4.0N/15mm),与日本同类产品性能相当.     

Optimisation of a process for shelf‐stable dietetic Chhana kheer and changes in physicochemical properties during storage

In the production of shelf‐stable dietetic Chhana kheer, optimised levels of Chhana and artificial sweeteners were examined using a stationary retort. The product was characterised by short lag period for heating (j_h) (0.78–1.03), small heating rate index (f_h) (7.69–17.00 min) and short lag factor for cooling (j_c) (0.76–1.06), implying convective heating regime. The total process time B was 19.13–32.98 min for corresponding process lethality values (F_o) of 4.56–25.50 min. Based on optimisation, processing of the dietetic Chhana kheer at 121.40 °C for 20 min was found to be the optimum. Optimised product was stable up to 90 days at 37 °C.     

The performance of organic and inorganic coated retort pouch materials on the shelf life of ready-to-eat rice products

The performance of organic and inorganic coated retort pouch materials on the shelf life of ready-to-eat (RTE) rice products was investigated. Two different retort pouch structures were used: the organic material coated retort pouch (ORG), organic material coated polyethylene terephthalate (PET)/biaxially oriented nylon (BON)/cast polypropylene (CPP); the inorganic material coated retort pouch (IND), aluminum oxide coated PET/BON/CPP. Two specific cooked rice products, plain and chicken-flavored cooked rice, were utilized for the comparison. For quantitative analysis, moisture content and lightness of the rice products were measured. The moisture content of both the plain and chicken-flavored rice packed in either pouch decreased slightly during the 12 week storage time after retort processing. However, there were no significant differences in quantitative analysis between the ORG and IND for both the plain and chicken-flavored cooked rice. A simple paired comparison test was used to evaluate the sensory characteristics of rice products. Overall, there were no significant sensory differences between the ORG and IND for both the plain and the chicken-flavored cooked rice. These results demonstrated that the newly developed ORG can be used as a retort pouch material for RTE rice products.     

Changes of radical-scavenging capacity and ferrous reducing power in chub mackerel Scomber japonicus and Pacific saury Cololabis saira during 4 °C storage and retorting

To clarify the effects of freshness of raw fishes and boil-retort process on the antioxidant activities, we determined stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging capacity and ferrous reducing power in the ethanol extract solution of chub mackerel Scomber japonicus and Pacific saury Cololabis saira meat before and after retort process (115 °C for 80 min). The antioxidant activities in boiled (mizu-ni) and canned fish were also investigated. The mizu-ni can products contain only fish meat and little salt. The radical-scavenging capacity was increased about ten times in chub mackerel and about six times in Pacific saury by the retort treatment. Both antioxidant activities of raw chub mackerel meat increased during 10 days storage at 4 °C. On the other hand, the increasing of antioxidant activity in the stored and retorted meat was observed until four days storage. In the case of mizu-ni canned products, the antioxidant activities were high in common-grade cans rather than high-grade cans. Almost the antioxidant activities shown in this study were correlated with absorbance at 245 nm. We consider that the results about differences of antioxidant activities between raw and retorted fishes or fresh and several day stored fishes are useful for the food functions and safeties.     

Textural and sensory characteristics of retort-processed freshwater prawn (Macrobrachium rosenbergii) in curry medium

Freshwater prawn in curry was thermally processed to three F₀ values of 6, 8, and 9 at 116°C. Total process times for F₀ values of 6, 8, and 9 were 53, 57, and 63 min, respectively. The cook value (CV) obtained at F₀ values of 6, 8, and 9 was 87.53, 107.93, and 117.55 min, respectively. Instrumental texture profile analysis revealed that except springiness, the values of hardness, gumminess, and chewiness decreased as the F₀ values increased. CIELAB values of L*, b*, and a* increased as the F₀ values were increased. The organoleptic evaluation scored the highest for the product processed to F₀ 7 min.     

Reliability of Destructive Leakage Detection Methods for Semirigid Retort Packages

Three different destructive testing methods for package integrity (biotesting, dye penetration and electrical conductance) were compared with each other using intact and leaking retort packages. In biotesting, both vegetative cells of Enterobacter aerogenes and spores of Bacillus subtilis were used as test microbes. The biotest results did not significantly differ from each other, most packages with a 50 μm channel leak through the seal area were contaminated. Biotesting with E. aerogenes was regarded as a more favourable method than testing with spores of B. subtilis since it was easier to perform and gas formation in the packages was a simple indicator for product contamination. The electrolytic test was able to discover most of the leaking packages more reliably than the biotests and the dye penetration test. The dye test had similar sensitivity in identifying leaks to that of the biotests. In conclusion, the microbial integrity of packages should not be estimated only by biotests, even if they are generally regarded as the most severe package integrity test methods.     

固体热载体干馏桦甸油页岩试验研究

设计并搭建了一套处理量为5 kg/h油页岩的回转干馏炉装置,以桦甸油页岩为原料,高温热灰作固体热载体,对该油页岩进行干馏特性试验研究。考察了干馏过程中油页岩出油率的影响因素,经试验发现主要包括固体热载体初温、回转干馏炉转速、固体热载体与油页岩混合比以及油页岩粒径大小。基于上述的实验结果研究了热载体初始温度600℃~800℃、回转干馏炉转速15 r/min~21 r/min、固体热载体与油页岩混合比2~5以及油页岩粒径分布0~5 mm对油页岩出油率的影响。研究结果表明：当固体热载体初温为750℃、回转干馏炉转速为19 r/min、固体热载体与油页岩比例为41及油页岩粒径大小在0~3 mm分布的工况下,油页岩的出油率达到最高,且为95%。