Chemical analysis of volatiles emitted by Pinus svlvestris after induction by insect oviposition

Gas chromatography – mass spectrometry analyses of the headspace volatiles of Scots pine (Pinus sylvestris) induced by egg deposition of the sawfly Diprion pini were conducted. The odor blend of systemically oviposition-induced pine twigs, attractive for the eulophid egg parasitoid Chrysonotomyia ruforum, was compared to volatiles released by damaged pine twigs (control) that are not attractive for the parasitoid. The mechanical damage inflicted to the control twigs mimicked the damage by a sawfly female prior to egg deposition. The odor blend released by oviposition-induced pine twigs consisted of numerous mono- and sesquiterpenes, which all were also present in the headspace of the artificially damaged control twigs. A quantitative comparison of the volatiles from oviposition-induced twigs and controls revealed that only the amounts of (E)--farnesene were significantly higher in the volatile blend of the oviposition-induced twigs. Volatiles from pine twigs treated with jasmonic acid (JA) also attract the egg parasitoid. No qualitative differences were detected when comparing the composition of the headspace of JA-treated pine twigs with the volatile blend of untreated control twigs. JA-treated pine twigs released significantly higher amounts of (E)--farnesene. However, the JA treatment induced a significant increase of the amount of further terpenoid components. The release of terpenoids by pine after wounding, egg deposition, and JA treatment is discussed with special respect to (E)--farnesene.     

Analysis of Volatiles Induced by Oviposition of Elm Leaf Beetle Xanthogaleruca luteola on Ulmus minor

Egg deposition of the elm leaf beetle Xanthogaleruca luteola causes the emission of volatiles from its food plant, Ulmus minor. These volatiles are exploited by the egg parasitoid, Oomyzus gallerucae, to locate its host. In contrast to other tritrophic systems, the release of volatiles is not induced by feeding but by egg deposition. Previous investigations showed that the release is systemic and can be triggered by jasmonic acid. Comparison of headspace analysis revealed similarities in the blend of volatiles emitted following egg deposition and feeding. The mixture consists of more than 40 compounds; most of the substances are terpenoids. Leaves next to those carrying eggs emit fewer compounds. When treated with jasmonic acid, leaves emit a blend that consists almost exclusively of terpenoids. Dichloromethane extracts of leaves treated with jasmonic acid were also investigated. After separation of extracts of jasmonate induced elm leaves on silica, we obtained a fraction of terpenoid hydrocarbons that was attractive to the parasitoids. This indicates that jasmonic acid stimulates the production of terpenoid hydrocarbons that convey information of egg deposition to the parasitoid.     

Resistances to UV-C irradiation of Salmonella Typhimurium and Staphylococcus aureus in wet and dried suspensions on surface with egg residues

To clarify the effects of food sediments on ultraviolet-C (254 nm) sanitation in food-related environments, we examined the resistance of pathogenic bacteria (Salmonella Typhimurium and Staphylococcus aureus) cells, in wet and dried suspensions adhered with 1.5-15% w/v egg albumen, 1.5-15% yolk or 3.0-30% whole egg solutions, against UV-C irradiation. Bacterial suspensions (0.1 ml of 8 log CFU/ml) were put on 47 mmφ glass dishes and dried at room temperature (20-24 °C) for 180 min in a bio safety cabinet with ventilation. Viable S. Typhimurium and S. aureus cells in distilled water decreased during the drying period from 7.2 to 3.2 and from 8.0 to 6.5 log CFU/dish, respectively,. On the other hand, the bacteria cells were protected from drying by egg compounds, even by the lowest concentration. The UV-C treatment (0.16 mW/cm² for 10 min) showed a clear bactericidal effect in the absence of egg compounds. However, the bactericidal effect was inhibited by 15% yolk and 30% whole egg. Results in this study suggested that the small food sediment protect bacteria on the surfaces from dryness and UV-C irradiation and it might introduce cross contamination.     

Bioavailability of the antioxidative thyme compounds thymol and p-cymene-2,3-diol in eggs

  p-Cymene-2,3-diol and thymol are components of thyme that exhibit antioxidative activities. The effect of dietary thyme extract on the bioavailability of these antioxidative compounds in egg was evaluated. A new method of analysing the dietary modified egg yolk was developed. Results showed that p-cymene-2,3-diol and thymol are bioavailable in egg yolk but not in albumen. Received: 26 August 1998 / Revised version: 28 October 1998     

超滤法提取蛋清溶菌酶

对蛋清料液进行前处理:采用磷酸盐缓冲液稀释10倍,在24MPa压力下均质;对超滤工艺进行了研究,采用截留相对分子质量为30000的聚醚砜(PES)膜进行超滤;溶菌酶制品活力为14610U/mg.     

Rheological properties of foams generated from egg albumin after pH treatment

Rheological properties of foams at pH 4.5 and 8.5 made from egg albumin proteins after pH-induced unfolding and refolding treatments were investigated. The foams behaved as highly elastic materials. Static and dynamic yield stress was investigated using small, steady shear experiments. Yield stress was measured also in oscillation mode and high correlation was found between dynamic yield stress and critical stress amplitude. All pH treatments led to firmer foams than untreated foams at pH 8.5. At pH 8.5 the control foam had a very weak structure (static yield stress at 3.4 Pa and dynamic yield stress at 5.5 Pa for the fresh made foams), while pH-treated foams at pH 8.5 had values (static yield stress up to 39.2 Pa and dynamic yield stress up to 47.1 Pa for the fresh made foams) that were even higher than the values for the control at pH 4.5 (static yield stress at 22.4 Pa and dynamic yield stress at 25.4 Pa for the fresh made foams, which is a good foaming pH for egg albumin). It was shown that an increase in yield stress of foams after drainage is related to foam stability and liquid drainage. This study demonstrated that unfolding egg albumin at low or high pH followed by refolding leads to a substantial increase in foam firmness and gives the foam different properties than foams from untreated egg albumin.     

鸡蛋素食肠生产工艺的研究

研究了5种食品添加剂、加水量和加热情况对鸡蛋素食肠凝胶性的影响，得出了鸡蛋素食肠的配方。     

袖珍型禽类产品的制作技术

本文介绍以禽类为原料加工生产传统型袖珍产品的新工艺，采用肉鸽加工烧鸡，用分割后的鹅腿加工中国传统型火腿，用鹌鹑蛋生产皮蛋等。该工艺在继承传统工艺的基础上，结合各原料的特点对传统工艺加以改进，并保持传统产品的特色和风味，对增加禽类产品的品种及促进禽类产品的销售，提高经济效益具有重要意义。     

溶菌酶及其在食品工业中的应用

溶菌酶是一种对人安全且具有保健作用的蛋白酶,是国际公认的绿色天然酶制剂。它在食品工业中被广泛用作食品添加剂和防腐剂。溶菌酶广泛存在于人、动植物及微生物体内,尤以鸡蛋清中含量较高,具有巨大的开发应用价值。     

木耳多糖鸡蛋素食肠加工工艺的研究

研究了黑木耳提取工艺，通过黑木耳多糖提取液、绿豆淀粉、复合磷酸盐和加水量四因素的正交试验，得出了鸡蛋木耳素食肠最佳配方为：鸡蛋38．5％、0．9％的黑木耳多糖提取液25％、绿豆淀粉5％、复合磷酸盐0．5％、水30％、食盐1．0％。