Advanced Materials Research Vols. 781-784

Abstract: Response surface methodology (RSM), based on Box-Behnken design principle, was employed to obtain the optimum combination of three natural preservatives in beef storage with controlled freezing point technique. Chitosan, Nisin and tea polyphenols were chosen as the optimization factors while investigated responses was total volatile basic nitrogen (TVB-N). The response surface plot and the contour plot derived from the mathematical models were applied to determine the optimal conditions. The Optimum combination of three preservatives was chitosan 1.70%, Nisin 0.03% and tea polyphenols 0.24%. The increasing rate of TVB-N was 49.34% on the 20^th day when beef was stored in controlled freezing point condition with the optimum combination of three preservatives, which was in good agreement with the value predicted by the model.

Abstract: HPLC (High Performance Liquid Chromatography) method for chloramphenicol residues in freshwater fish was developed. The samples were extracted with ethyl acetate. The LC was performed on a C18 column, mobile phase consisted of methanol-water (45:55 v/v) and eluted at 0.2mL/min at 20°C, inject volume was 20μl. The linear rang for chloramphenicol residual is within 0.5-20μg/mL, the limit of detection is 0.01ng/g. The average recovery is 80.06%-92.71%, and the RSD is 1.46%-5.61%. This method is employed to analyze freshwater fishes, such as catfish, chub and carp.

Abstract: The effects of 1-MCP treatment on the ethylene synthesis of Yali pear seeds of different harvest maturity were evaluated during storage. Yali pear fruit (early harvested and late harvested) were treated with 1.0 μL.L^-1 1-MCP for 20 h at room temperature, packaged in PE plastic film and then stored at 0±1°C for 180 days. The results show that the respiration, ethylene production, ACC content, ACO and ACS activities of the seeds of early harvested Yali pear fruit with 1-MCP treatment decrease significantly during storage, the peaks decrease and are delayed for 60 days. But 1-MCP treatment has no significant effects on the indexes related with ethylene synthesis to the seeds of late harvested fruit. 1-MCP can be used to inhibit the synthesis of ethylene in the seeds effectively and keep the quality and extend the shelf life of early harvested Yali pear fruit.

Abstract: A convenient way of producing effective antibody against maize seed storage proteins is present.The protein patterns of maize hybrid seed Ludan50 have two special protein bands with Polyacrylamide gel electrophoresis (PAGE) which was corresponding to its parent inbred lines Luyuan92 and Qi319. We purified the two proteins respectively by acid-PAGE and then immunized rabbit and laying hens, obtained the antiserums and yolk antibodies. Both antiserums and yolk antibodies have good specificity against the antigens, except that the yolk antibody has a higher titer. We also measured its specificity against different protein components extracted with pure water, 2.5% NaCl (w/v) , 70%(v/v) alcohol , 10mM HCl and 50mM KOH. The results appears that the water-soluble proteins tended to be more specific than othors to the antibodies, so the two inbred lines can be identified from each other by ELISA with the antibody we have been produced.

Abstract: The different factors of influencing viscosity of acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) from Amiurus nebulosus skin were studied. Influence of concentration, pH value, temperature and standing time on their viscosity properties were tested. The results showed that the viscosity of ASC and PSC increase with the increasing of the concentration of collagens, and decreased with the increasing of temperature. And the viscosity decreased at first with the prolonging of the storage time, after that increased up to maximum, then decreased again. The effect of pH on viscosity is very complex, the maximum viscosity value of ASC and PSC were at pH 7.0.

Abstract: During fish processing, a large amount of waste, of the original raw materials is generated, such as skin, bone, scale, viscera and head. These useful resources have been mainly used as feedstuff or fertiliser with low value. To make more effective use of underutilized resources, collagen was isolated from the skin of Amiurus nebulosus using acetic acid and characterized for their potential usage in commercial applications. The yield of acid-soluble collagen (ASC) was 62.05% while the maximum absorbance of ASC was at 234 nm. Amino acid composition and SDS - PAGE suggested that the collagen is possibly possessive of type I collagen. Moreover, FTIR investigations showed the existence of helical arrangements of collagen where the denaturation temperature (Td) and shrinkage temperature (Ts) were 29.8°C and 65.12°C, respectively. There is a possibility that ASC could be utilized as an alternative source of collagen for food, cosmetic, biomedical and pharmaceutical purposes.

Abstract: The effect of coconut water contents, sucrose and ammonium sulfate concentrations, cultivation modes on the growth of Gluconacetobacter xylinus Y15 was investigated. When 25%(V/V) coconut water, 3g/L (NH₄)₂SO₄ was added into the medium without sucrose, and G. xylinus Y15 was cultivated in shake flask culture at 130r/min for 24h, the cell number could reach as high as 4.9×10⁸CFU/mL, while the cell number was only 4.9×10⁴CFU/mL when cultivated in static culture. The growth curves of G. xylinus Y15 in coconut water medium and HS [ medium in shake flask culture were compared. The lag phase of G. xylinus Y15 in coconut water medium was 20h shorter than in HS medium, and the log phase was 20h longer.

Abstract: Maize is the second large crop in China that needed 100-120 million tons seeds for an average year and the production loss caused by inferior seeds was amazing. Bing an allogamous wind-pollinated plant, maize hybrid purity problem is mainly reflected the inbred lines seed mixed in hybrid. Therefore it is important to have specific and sensitive purity test methods to prevent the poor seeds into market. In this paper, we developed an inderect ELISA using polyconal antibody against maize inbred lines to bind extracts from whole grain with pure water. The single blind trial demonstrated that the average detectable rate of indrect ELISA was 95.2%. We also extended this method to other maize hybrid varieties, found it has no ability to descriminate the maize hybrid facticity.

Abstract: The presence of heavy metals in the environment can be detrimental to a variety of living species including human. River crabs are sensitive to heavy metals .The concentrations of cadmium, copper, lead and zinc were analyzed in muscles, hepatopancreas, gills and exoskeletons using ICP-MS . Zinc was greater in muscles and hepatopancreas, whereas copper was greater in muscles and gills. Cadmium and lead were within the range of limits for hazardous substance about the pollution-free food. Then river crab can be an effective bioindicator for assessing metal levels in environment.

Abstract: Using Box-Behnken center composite design of three variables with three levels, the optimal extraction process for carotenoids from tamarillo fruits were determined by response surface methodology. The optimal extraction process was obtained as followed: solid-liquid ratio of 1:19.02(g/mL), extraction temperature of 44°C, and extraction time of 33.68 min. Under these conditions, the extraction of carotenoids content was 5.755[mg/100, similar to the theoretical prediction of 5.885[mg/100. This study confirms the efficiency of RSM as a simple and effective method and the great potential of tamarillo fruits as a health food and a resource of carotenoids.