Study on the glass transition for several processed fish muscles and its protein fractions using differential scanning calorimetry

ABSTRACT:   The glass transition behavior of processed fish muscles (bonito, tuna, mackerel, sea bream, cod) and its muscle protein fractions (sarcoplasmic and myofibrillar proteins) were studied using differential scanning calorimetry. Each dried processed fish muscle and the extracted protein fractions showed clear glass transition phenomenon. The T _g values of muscles and myofibrillar proteins from red muscle fishes tended to be lower than those from white muscle fishes though there was no difference on T _g of sarcoplasmic proteins. The T _g value of whole muscle was considerably lower than that of extracted protein fractions because of the plasticizing effects of low molecular weight materials contained in the muscle.     

Fractal analysis of ice crystals in frozen food

Fractal analysis of the morphology of ice crystal particles in frozen food was attempted for frozen soybean curd (tofu). From a microscopic image analysis of the ice crystal particles, it was found that the perimeter of the ice crystal particles could be recognized as a fractal. Effects of the storage time and storage temperature on the fractal dimension (d(p)) of the perimeter of the ice crystal particles were also investigated. As storage time was increased, the d(p) value tended to decrease. When the storage temperature was increased, the value of d(p) decreased more rapidly. The changes corresponded to the visual observation of the shape change for the ice crystal particles during storage reported by many researchers, suggesting that the fractal dimension d(p) could be used as a quantitative indicator reflecting the surface roughness of ice crystal particles.     

马传染性贫血病马与弱毒疫苗免疫马的区别试验

 本文应用淋巴细胞杂交瘤技术研制出具有抗马传染性贫血病驴白细胞弱毒抗原株系特异性的单克隆抗体（McAb）的酶结合试剂，以斑点试验（DB）与琼脂免疫双扩散试验（ID）相结合的方法，用于马传贫病马与马传贫驴白细胞弱毒疫苗免疫马血清抗体的鉴别。使用本方法对339匹实验马进行测试，共检出马传贫病马11匹，马传贫驴白细胞弱毒疫苗免疫马239匹，既未接种弱毒疫苗又未感染马传贫马89匹。另外，对106匹人工马传贫病马和21匹马传贫弱毒疫苗免疫马作了病理学验证，结果与免疫学检测相符。疫区在清除病马之后，病情停息。疫苗免疫马经贸易成交，更换畜主后，再次检疫未发现马传贫病例。结果表明，本方法对马传贫病马与马传贫驴白细胞弱毒疫苗免疫马的区别诊断有实用价值。     

Change of K value and water state of yellowfin tuna Thunnus albacares meat stored in a wide temperature range (20°C to −84°C)

SUMMARY: The study on K value change at low temperature storage had been carried out down to a temperature of −40°C, however, there was no evidence about this reaction rate if the temperature were lowered below the storage temperature normally used especially for tuna meat (−60^oC). The rate of K value change ( k_f ) of yellowfin tuna ( Thunnus albacares ) meat was determined during storage at a wide temperature range (20°C to −84°C). The logarithm of K '(= 100 − K value) was used in this study and its plot against storage time yielded a straight line, which indicated an apparent first-order reaction for all temperature storage. Furthermore, physicochemical characterization of water in tuna muscle was carried out using Differential Scanning Calorimetry (DSC) at very low temperature. The temperature dependence of this reaction was analyzed by an Arrhenius's plot that resulted in two break points. The first break point occurring at freezing point might be due to the freeze effect. The second break point was at −10°C. The reaction rate change steeply declined at the temperature range of −70°C to −84°C, and was thought to be related to glass transition which may occur in the fish sample.