STUDIES ON POSTHARVEST PHYSIOLOGY AND THE STORAGE TECHNOLOGY OF MANGO (MANGIFERA INDICA L.)

Mango (Mangifera indica L. cv. Hongxiangya and Wacheng) was chosen to study the effect of postharvest biological characters in different storage conditions. The determining items included respiratory rate, total sugar, vitamin C (Vc) content, firmness, polyphenol oxidase (PPO) and peroxidase (POD). The results showed that both 8 and 11C were the better storage temperatures, and the storage life would last 50 days in this situation. The respiration rate increased quickly between the 16th to the 22nd days; the peak values were the 28th and 25th days at 8C for Hongxiangya and Wacheng, respectively. The flesh firmness decreased dramatically at 6 days after harvest. Total sugar content, Vc content, PPO and POD increased at first and then decreased. The color changed from green to yellow with the increase of carotenoids content. After treatment with thiabendozole and iprodione, the number of rot fruits was markedly lower than the other treatments. The best temperature is 11 and 14C for Hongxiangya and Wacheng, respectively. The rot rate is 6.77 and 8.33% with 1,000‐ppm iprodine treatment after 50‐days storage.     

POSTHARVEST CHANGES OF PECTIC SUBSTANCES IN CHILLED PEACHES

ABSTRACT Red Globe peaches were harvested at the threshold-mature stage and either stored at OC after preripening at 20C for 48 h or stored directly at 2C. Total pectin increased from 7.49 mg/g fresh weight in the threshold-mature sample to 10.21 mg/g in pre-ripened fruit stored at OC and 12.83 mg/g in fruits stored directly at 2C. Depending on extraction and storage protocol, between 26% and 73% of total pectin was solubilized. Chelator-soluble fractions had a low degree of esterification (DE ca. 20%), whereas other fractions were highly methylated (DE ca. 56% to 74%). Average DE did not vary between samples. DEAE-cellulose chromatography revealed an uneven distribution of methoxyl groups. Two prominent peaks were observed in chromatograms of chelator-soluble extracts from threshold-mature fruit and fruit stored directly at 2C. One peak was observed in chelator-soluble pectin from preripened fruit stored at OC.     

RETARDATION OF OXIDATIVE COLOR CHANGES IN RAW GROUND BEEF

SUMMARY— Ascorbic acid plus either BHA or PG effectively retarded both lipid and pigment oxidation in raw ground beef for up to 8 days of refrigerator storage in oxygen-permeable film. Both trained and consumer-type panels judged the additive-treated meat to be significantly better than controls. Percent metmyoglobin was found to be a useful objective measurement of color in raw beef, but total pigment concentration did not provide an adequate evaluation of color. Treatment with these additives did not appear to mask bacterial spoilage.     

EFFECTS OF DIETARY CABBAGE (BRASSICA OLERACEA L.) ON THE TUMORIGENICITY OF 1, 2-DIMETHYLHYDRAZINE IN MICE

Diets containing dehydrated cabbage (Brassica oleracea L.) were fed to weanling male C57 BL/6 mice for nine months. Diets known to be adequate in all nutrients for mice were modified to include ground dehydrated cabbage leaves to 0, 10, 20, and 40% of their diet while holding protein, crude fiber, and lipid at constant levels. The animals were subcutaneously injected with 20 mg of 1, 2-dimethylhydrazine (DMH) per kg body weight at weekly intervals for 36 weeks. The DMH carcino-genicity varied with the proportion of cabbage in the diet and the tissue. Diets containing 10 and 20% cabbage enhanced DMH tumorigenicity while cabbage at 40% provided a protective effect. Tumors on the spermatic cord were the most predominant with occasional occurrence of kidney and liver tumors. Tumorigenicity is discussed in terms of two hepatic enzymes, cytochrome p-450 and p-nitroanisole-o-demethylase.     

ANTTNUTRITIONAL FACTORS AND TOXICITY IN RAW DRY BEANS (Phaseolus vulgaris, L.) OF 12 BRAZILIAN CULTTVARS

In the present work, the relative toxicity of 12 cultivars of raw dry beans was studied. When raw dry bean flours were given in the diets as the only source of protein the Wistar rats died within 3.8 (Goiano Precoce) to 8.4 days (Aroana). When whole seed flour was mixed with casein, strong impairment to ration utilization and animal development was observed, which was measured as loss of weigh:, decreased protein digestibility, decreased biological value and net protein utilization. A positive and significant correlation between toxicity and hemagglutination activity was established. On the other hand, antitryptic activity and tannin content did not show any correlation with the toxic effect. The deterimental effect of the lectins was evident by their interaction with the intestinal mucosa, which resulted in rupture of intestinal villii thus causing interference with absorption. These effects, when strong and prolonged, can cause the rat's death, in spite of the rat's adaptive and recovering capacity.     

刹克龙在浸出车间的运用

简要介绍了刹克龙用于浸出车间气—固,固—液,气—液等介质分离的实例,并说明了问题所在。     

图谱法在采后果蔬果胶分子结构研究中的进展

细胞壁中的果胶物质是维持果蔬质地的重要成分.阐明果蔬中果胶的结构及在贮藏中的变化对指导采后果蔬有重要意义.简述近年来应用较广的傅里叶变换红外光谱(FTIR)、基质辅助激光解吸电离质谱(MAlDI-MS)、核磁共振(NMR)、原子力显微镜(AFM)等图谱法的原理、优点以及它们在检测采后果蔬中果胶分子结构及变化的进展,并对果胶分子结构检测技术的发展方向进行展望.