低剂量γ辐照对牛肉肌内脂肪酸组成及牛肉质量的影响

取8头黄牛的半腱肌,在60Co源下辐照,剂量分别1.13,2.09及3.17kGy,牛肉在7℃环境下储存10d,评估不同辐照剂量和储存时间(0d或10d)条件下肌内脂肪酸组成及牛肉质量的变化.肉样储存10d后,未辐照的肉样中SFA和MUFA含量比未储存未辐照的牛肉(0d,0kGy)显著上升,而辐照过的肉样SFA和MUFA含量基本不变.辐照后多不饱和脂肪酸(PUFA)、n-3PUFA、n-6PUFA含量和P/S显著下降(0d或10d).不同辐照剂量对脂肪酸的影响差异不显著.辐照后0d,牛肉样滴水损失及TBARS与辐照剂量呈正相关,随着辐照剂量的增加(从0kGy到3.17kGy),滴水损失及TBARS逐步升高;而10d储存后,滴水损失和TBARS则与辐照剂量呈负相关.辐照后牛肉样细菌总数随辐照剂量的增大显著下降.牛肉肌内脂肪脂肪酸组成和比值因辐照而产生变化,而辐照剂量的增加(1.13kGy到3.17kGy)对脂肪酸组成没有显著的影响.3kGy左右的低剂量辐照可以很好的确保牛肉质量,而不会引起脂肪营养较大的损失.     

Gamma Irradiation Effects on Thiamin and Riboflavin in Beef, Lamb, Pork, and Turkey

A study was made of the loss of thiamin and riboflavin due to gamma irradiation of beef, lamb and pork longissimus dorsi, turkey breast and leg muscles. Thiamin losses averaged 11%/kiloGray (kGy) and riboflavin losses 2.5%kGy above three kGy. The rate of loss of thiamin in beef was higher than that in lamb, pork and turkey leg, but not turkey breast. with losses of 16%/kGy in beef and 8%/kGy in lamb. The rate of thiamin loss was not related to sulfhydryl, protein, moisture, fat or water content, pH or reducing capacity by redox titration. Loss of riboflavin was not different among species. Any detriment from such slight losses would seem to be more than compensated by the advantage of controlling bacteriological contamination by irradiation processing.     

辐射对淀粉作用的研究概况

介绍了近年来国内外研究辐射对淀粉作用的概况，总结了电离辐射对淀粉理化性质的影响，简单阐述了辐射对淀粉作用的机制。研究表明：淀粉经辐射后，淀粉链断裂，聚合度下降，对酶的作用敏感，辐射对淀粉的破坏程度与辐射剂量成正相关。     

Effects of Gamma Irradiation at -78°C on Microbial Populations in Dairy Products

The effect of low temperature (-78°C) gamma irradiation was investigated on microbial populations in selected dairy products to determine the irradiation dosage needed to produce commercially sterile dairy products for immunosuppressed patients. 40 kGy irradiation was sufficient to sterilize ice cream and frozen yogurt, but not mozzarella or Cheddar cheeses. Up to 8 wk continued incubation of the 40 kGy irradiated products at 7°C or 35°C resulted in no resuscitative growth in ice cream or yogurt, but identifiable growth in the cheeses. The 12D for B. cereus preinoculated into cheese and ice cream was 43-50 kGy.     

Transformation of Tapioca Starch by Gamma Irradiation

Results indicated that gamma irradiation altered the physical and chemical properties of tapioca starch. There was a remarkable decrease in starch viscosity as well as gelatinization temperature and time, swelling capacity, and molecular degradation occured after treating starch with different doses of gamma irradiation. The acidity, reducing sugars and solubility increased when tapioca starch was treated with different doses of gamma irradiation.     

A High Yield of Amylase from Aspergillus niger by the Effect of Gamma Irradiation

When irradiated rice starch was used as a media for Aspergillus niger a noticeable increase of amylase production was observed. Molecular degradation of starch molecules did occure, and an increase in starch acidity and solubility was noticed, whereas a marked decrease in viscosity as well as swelling capacity was observed. Gelatinization time and temperature of irradiated starch became shorter or lower resp. These results showed that internal changes in irradiated starch molecules and an alteration in its molecular configuration occured. They may affect the pathway of the growth of the fungi Aspergillus niger. When the amount of amylase was determined by measuring enzyme activity, it was observed that amylases in the irradiated media were higher than in the control media.     

Degradation of Corn Starch under the Influence of Gamma Irradiation

Irradiation of corn (maize) starch with different doses of gamma irradiation ranging from 1 × 10⁵ rad to 1 × 10⁶ rad resulted in the increase of starch acidity and reducing power. Molecular degradation was observed as a result of marked decrease in starch viscosity and intrinsic viscosity as well as swelling capacity. The gelatinization time and temperature of the irradiated starch became shorter than in the control sample. Internal changes in the irradiated starch occured as a result of lowering the number of glucose unit per segment in the irradiated starch molecules. All changes were proportional to the doses of gamma irradiation used.     

Effect of Gamma Irradiation on Whole-cell Glucose Isomerase

Gamma-rays induced inactivation of Actinoplanes missouriensis and Streptomyces olivaceus glucose isomerase has been studied. This enzyme exhibits high resistance against ionizing radiation. The D₃₇ value was found to be equal to 131 kGy for Actinoplanes missouriensis cells and 88 kGy for Streptomyces olivaceus cells when irradiated in the dry state in the presence of air. Mg²⁺ ions do not affect the radiosensitivity of the enzyme in cells, while the addition of Co²⁺ ions to the cell suspension increases its stability against ionizing radiation.     

辐照处理对魔芋葡甘聚糖肠道益生作用的影响

为探究辐照改性技术对魔芋葡甘聚糖（konjac glucomannan,KGM）肠道益生性的影响,以60Co为辐射 源制备0、10、20、30 kGy辐照剂量的KGM样品,采用健康志愿者粪便体外厌氧发酵,比较不同辐照剂量KGM 体外发酵液pH值、短链脂肪酸含量、有益菌及有害菌数目、双歧杆菌数量/大肠杆菌数量（B/E值）、益生元指数 （prebiotic index,PI）的差异。结果表明：相对于葡萄糖阳性对照,不同辐照剂量KGM均能有效降低发酵液pH 值,维持酸性环境,促进短链脂肪酸生成,同时改善发酵液微生物构成,提高B/E值及PI。在0～30 kGy辐照范围 内,随辐照剂量增大,KGM发酵液短链脂肪酸生成量增加,PI升高,0、10、20、30 kGy KGM的PI分别为0.48、 0.61、0.76、0.78。综上,KGM具有良好的肠道益生元作用,γ-辐照改性有助于进一步提高KGM的肠道益生性,综 合考虑辐照效率及KGM肠道PI,推荐20 kGy作为制备KGM低聚糖的适宜辐射剂量。     

Improving of Egyptian Rice by Means of Gamma Irradiation

Gamma irradiation caused reduction in cooking time with rice grains. Improvement in texture, flavor and appearance was observed. Irradiation caused degradation of starch molecules followed by decrease of viscosity of rice starch. Irradiated rice became more soluble, and its swelling capacity was decreased. These changes enhanced the extent of softening upon cooking and shortened cooking time. Degradation of the thin protein film that covers rice starch granules due to irradiation is confirmed by the increase of free amino groups in the rice flour extract. This leads to a quicker penetration of water to the inner part of rice grains.     

Gamma Irradiation Influence on the Storage and Nutritional Quality of Mushrooms

SUMMARY– Growth of freshly harvested mushrooms subjected to 100 krad of gamma irradiation is markedly inhibited, as measured by the small number of broken veils. This could significantly increase the storage life of mushrooms even under suboptimal conditions. Untreated mushrooms were preferred to the treated, but hedonic scores indicated that the treated mushrooms would be acceptable. There was no significant change in rate of moisture loss, or in reducing sugar or dry matter content of the irradiated mushrooms. Respiration of irradiated mushrooms is accelerated up to about 3 days after treatment and then slows markedly. The inclusion of 20% irradiated mushrooms in mouse diets fed in late pregnancy and lactation had no significant effects on the average mouse weight of the offspring 40 days old or on their daily food intake and weight gain in a subsequent 6-wk feeding period.     

Effect of Gamma Irradiation on Egyption Sweet Potato Starch

Results showed that treatment of sweet potato starch with different doses of gamma irradiation caused increase in starch acidity and reducing sugars as well as molecular degradation, occurred as a result of the marked decrease in viscosity and intrinsic viscosity and water absorption while the solubility increased.     

Sterilization of Ground Prepacked Indian Spices by Gamma Irradiation

Prepacked ground Indian spices which included pepper. turmeric, chilli, and coriander were found to be heavily contaminated with bacteria and molds. The total bacterial counts ranged between 10⁵–10⁷. whereas total fungal counts ranged between 10²–10⁶. Red chilli was found to be the most contaminated spice. The bacterial population consisted mainly of spores. A dose of 10 kGy was found to be effective in destroying these microbes in prepacked spices without affecting their quality attributes. To eliminate mold contamination a dose of 5 kGy was sufficient. During a six-month storage study of irradiated and unirradiated spices, the irradiated spices were found to retain their quality.     

Improving of Starch Gel Electrophoresis Technique by Gamma Irradiation

Electrophoresis as well as starch gel technique are considered nowadays the best way of protein fractionation. This research was carried out towards improving that technique by modifying the gel properties by treating starch with gamma irradiation. Results indicated that gamma irradiation modified the starch molecules as its viscosity and its intrinsic viscosity were decreased and molecular breakdown and degradation occurred as well as modified amylose to amylopectin ratio and increased retrograded starch, leading to the improvement of the properties of the produced modified starch gel when compared to control sample. Protein electrophoresis confirmed this improvement because of the better fractionation of wheat gluten when the modified starch gel was used than with the control, as the modified starch gel was more transparent and flexible and had a longer distance of run than control sample. High molecular weight protein was able to migrate through modified starch gel contrary to unirradiated sample.     

Modification of Corn Starch and Fine Flour by Acid and Gamma Irradiation. Part 1. Chemical Investigation of the Modified Products

Fine flour from corn and the isolated starch were dextrinized in the presence of acid and irradiated with y-rays. Starch irradiated with high doses of y-rays was highly modified while fine flour was less affected. The irradiated starch was reduced with sodium borohydride and then hydrolysed. Erythritol and other compounds were identified in the hydrolysate. It was concluded that the C2-C3 bonds in the intermediate glucose units are probably broken by irradiation. Such hypothesis was confirmed by periodate oxidation, hydrolysis with α-amylase and ferricyanide number determination of the irradiated starch.     

北京市区流通领域生鲜牛肉及制品市场调查报告

为摸清我国牛肉生产流通领域分割现状,促进牛肉产业的进一步发展,我们对北京市进行了为期近1个月的市场调查。结果发现,我国存在牛肉分割方法不统一,命名混乱,地区间价格差异大,食用方法不清等问题并给出了几种牛肉增值途径。     

Liking of Ground Beef Patties is Not Affected by Irradiation

ABSTRACT: Our objectives were to determine the acceptability of irradiated fresh ground beef and to determine whether the acceptability was affected by information about benefits or by identifying the samples. The 218 subjects were separated into 4 groups comprising a 2 × 2 design of benefits and information. All subjects tasted 4 patties: 2 irradiated and 2 control. Ratings of overall liking, toughness, and flavor and texture liking were equal for both. Subjects rated the irradiated beef patties juicier than the nonirradiated. Benefit information and sample identification increased the liking ratings of the patties-because the group with no benefit information and no sample identification generally rated all samples lower.     

辐照对Pen a1抗原表位免疫原性的影响

辐照处理刀额新对虾中主要过敏原Pen a1,采用SDS-PAGE,MOLDI-TOF MS方法分析辐照处理对虾致敏蛋白Pen a1分子质量的影响,同时利用表位抗体进行免疫印迹及间接竞争ELISA法评估Pen a1中5种抗原表位免疫原性的变化情况。结果显示:与未处理相比,6.7 k Gy辐照处理能够破坏部分Pen a1蛋白结构,导致裂解和聚合现象的发生。5种抗原表位免疫原性均未降低,并有不同程度的增加,其中Epitope1,2,3,4的IC50值约为对照的4/5,Epitope5的IC50值变化不大,说明其对辐照处理较稳定。低剂量的辐照处理不能降低Pen a1抗原表位的免疫原性。     

Effects of Gamma Irradiation on the Texture of Minimally Processed Apple Slices

ABSTRACT: Fresh-cut apples with or without calcium treatments were irradiated at doses up to 5 kGy at 0.4 and 2 kGy.h^-1 dose rates with a Co⁶⁰ source in 0, 21, and 100% O₂ atmospheres. Firmness decreased as irradiation dose increased beyond a 0.34 kGy threshold. High dose rate initially resulted in less softening compared to low dose rate, but dose rate became insignificant upon storage. Irradiation atmosphere did not affect firmness. Softening of irradiated slices correlated positively with water-soluble pectin, and negatively with oxalate-soluble pectin content. Calcium prevented irradiation-induced softening of thin slices (3-4 mm thick), but was not effective with thicker wedges due to limited penetration.