New package system for fresh berries

This paper presents the design criterion and evaluation of a new package system designed to ship fresh strawberries and raspberries. the study describes the evaluation of the new package systems for pre-cooling after field picking. in addition data is presented describing damage to berries in the form of bruising and cutting owing to vibration in shipment. the paper compares this new concept to the traditional polyethylene injection moulded baskets used in the usa for the past 30 years.     

生鲜鸡肉货架期预测模型的建立与评价

为了建立生鲜鸡肉货架期的动力学模型,将自然污染的生鲜鸡肉经PS/PE托盘包装后,置于0、5、10、15、20、25℃贮藏,分别测定不同贮藏时间的假单胞菌数量,同时对5℃贮藏的生鲜鸡肉进行品质分析,确定腐败限控量。结果表明:假单胞菌用来预测生鲜鸡肉时的腐败限控量为5.39(lg(CFU/g)),Gompertz函数能很好的描述假单胞菌在不同温度下的生长动态,建立6种温度条件下假单胞菌在生鲜鸡肉中的生长模型。采用Belehradek方程描述温度对最大比生长速率和延滞时间的影响,呈现良好线性关系,模型残差值的绝对值均小于0.07,表明该模型描述的温度与比生长速率和延滞时间是可信的。在此基础上,建立了生鲜鸡肉贮藏过程中货架期的预测模型。     

Performance of MUF resins for particleboard before and after spray-drying

Melamine-urea-formaldehyde (MUF) resins can be spray-dried to obtain resins in powder form and indefinite shelf-life. Application as particleboard adhesives of such resins after redissolving in water yield resins of excellent performance as particleboard adhesives if the natural advancement caused by the heat in the spray-drier chamber is taken into account. Solid-state cross-polarization/magic angle spinning ¹³C nuclear magnetic resonance (CP–MAS ¹³C NMR) analysis of the spray-dried resin in powder form and thermomechanical analysis (TMA) has shown some difference in behavior in relation to MUF resins of the same level of water tolerance which have not been spray-dried. These small but significant differences can be ascribed to differences in resin structure.     

Quality of rainbow trout chilled-stored after post-catch holding

The shelf-life of headed and gutted rainbow trout (Salmo gairdneri) was evaluated over period of storage at 0°C. There were three groups of samples: (i) fish held at 10°C for 6h and iced, (ii) fish held at 20°C for 6h and iced and (iii) fish held at 30°C for 6h and iced. Quality was assessed over the period of iced storage by measurements of total volatile bases (TVB), hypoxanthine, thiobarbituric acid, pH, water holding capacity (WHC) and tissue compressibility (TC). The results indicated that holding at various time/temperature periods before icing influences quality over the period of iced storage. Deterioration in quality was most pronounced when the fish had been held at high ambient temperatures of 30°C. Hypoxanthine values appeared to give an accurate indication of quality of freshwater fish. There was a linear increase in hypoxanthine values over the period of iced storage for all samples. However, for trout held at 30°C for 6 h before icing the values appeared to be highest. The coefficients of linear regression for fish iced immediately on receipt were lowest per day. It is suggested that hypoxanthine values may be used as chemical indicators of quality of freshwater trout.     

Detection of expired vacuum-packed smoked salmon based on PLS-DA method using hyperspectral images

Consumers want fresh food with a long shelf-life, which in 2010, resulted in an important increase in packaged and processed food. This is especially important for fishery products due to their highly perishable nature. One problem is that it is not possible to measure freshness in packaged food only using the visible spectrum. Moreover, the detection of freshness is a complex problem as fish has different tissues with different biodegradation processes. Therefore, it would be especially interesting to have a non-destructive method to evaluate the shelf-life of packed processed fish. This paper proposes a method for detecting expired packaged salmon. Firstly, this method uses hyperspectral imaging spectroscopy (HIS) using visible and SW-NIR wavelengths. Secondly, a classification of different salmon tissues is carried out by image segmentation. Finally, classifications of expired or non expired salmon are performed with the PLS-DA statistical multivariate method due to the large amount of captured data. In a similar way, spectral data and the physicochemical, biochemical and microbiological properties of salmon are correlated using partial least squares (PLSs). The result obtained has a classification success rate of 82.7% in cross-validation from real commercial samples of salmon. Therefore, this is a promising technique for the non-destructive detection of expired packaged smoked salmon.     

Effect of the gas/product ratio and CO2 concentration on the shelf-life of MA packed fish

Rainbow trout and Baltic herring fillets were gas packed at two different gas/product ratios and two different CO² concentrations. Two reference samples were used; one frozen and one vacuum packed. Changes in gas composition in the gas packages, microbial and sensory quality, K values and drip formation of the fillets were investigated during storage at 2°C. A gas/product ratio of 100 ml/100g gas package was as effective as a vacuum package in preserving the microbial quality of fish and a gas/product ratio of 40ml/100g gas package was as effective as a vacuum package in preserving the sensory quality of fish.     

Yield and storage stability of patties from pre-rigor beef previously dipped in potassium sorbate and ginger solutions

Pre-rigor beef strips dipped for up to 3 min in solutions of 2% ginger, 4% potassium sorbate or both were minced and made into patties. Meat yield before frying did not increase, but after frying the cooked pattie yield did increase with the mixed treatment. Yield increase was greatest with microwave cooking. There were no significant effects on pH, free fatty acids or TBA values, but slightly reduced total aerobic plate counts with the sorbate treatments when patties were stored at 5–7°C.     

Physical measurement of the quality of fresh scad (Trachurus trachurus) and rainbow trout (Oncorhynchus mykiss) during ice storage using the RT Freshmeter

The RT Freshmeter was used to obtain a quality index of two Portuguese fish, scad ( Trachurus trachurus ) and farmed rainbow trout ( Oncorhynchus mykiss ). The curves obtained were comparable to those previously published using the GR Torrymeter. However variations were lower during the first phase of storage and it was observed that the curves could be divided into two distinct regions. The slope of the linear regression was higher during the first 5 days of storage, representing the first region of the curve, in both fish studied.
It is proposed that the two different rates of change of the quality index obtained with the meter reflect the two predominant spoilage mechanisms, enzymic and microbiological. The RT Freshmeter measurements are compared to organoleptic changes.
Preliminary results obtained with the RT Freshmeter on rainbow trout fillets without skin indicate that this instrument is not suitable for use with this product due to large variations and curve slopes close to zero.     

Age gelation in UHT-processed reconstituted concentrated skim milk

UHT reconstituted concentrated skim milks made from high-heat powder had considerably longer gelation times than those made from medium- or low-heat powders. Addition of hexametaphosphate to the concentrated milk before UHT processing markedly delayed the onset of gelation during storage. Sediment formation was greatest in the UHT concentrated skim milk made using high-heat powder followed by samples made using medium- and low-heat powders, respectively. The extent of proteolysis, as measured by 12% TCA-soluble amino groups, increased at a faster rate in the UHT milks stored at 40°C than in those stored at 22°C but decreased with increasing heat treatment of the milk prior to powder manufacture. The electrophoretic patterns of samples stored at 22°C clearly showed the breakdown of β-casein with a corresponding increase in slower moving bands, presumably γ-casein and proteose-peptone components. However, storage of samples at 40°C resulted in diffused 'blurred' protein patterns with some protein material not entering the resolving gel. At 22°C there was some evidence of proteolysis but no evidence of high molecular weight polymer formation, while at 40°C both proteolysis and high molecular weight polymer formation increased with storage time. It appeared that both physico-chemical and proteolytic processes play some part in the mechanism of gelation in UHT reconstituted concentrated skim milk.     

Limitations to modified atmosphere packaging for extending the shelf-life of partly ripened Doyenné du Comice pears

Although some retardation in ripening of Doyenne du Comice pears can be obtained when unripe fruit are held in modified atmosphere packs (MA) at 20°C, softening proceeds at a faster rate than chlorophyll loss so that the appearance of the fruit fails to match its internal condition. However, a 4-day extension in shelf-life was obtained by packing the fruit in a part-ripe condition and, although the effects on rate of softening were less than those seen for unripe fruit, the yellower ground colour was more consistent with the eating qualities of the fruit. Increases in fruit-to-fruit variability, and in the risk of skin injury as the pears ripen in MA packs which were also recorded, are likely to preclude the commercial adoption of this technique for Comice pears.