Conversion of acid oil by-produced in vegetable oil refining to biodiesel fuel by immobilized Candida antarctica lipase

Acid oil, which is a by-product in vegetable oil refining, mainly contains free fatty acids (FFAs) and acylglycerols, and is a candidate of materials for production of biodiesel fuel. A mixture (acid oil model) of refined FFAs and vegetable oil was recently reported to be converted to fatty acid methyl esters (FAMEs) at >98% conversion by a two-step reaction system comprising methyl esterification of FFAs and methanolysis of acylglycerols using immobilized Candida antarctica lipase. The two-step system was thus applied to conversion of acid oil by-produced in vegetable oil refining to biodiesel fuel. Under similar conditions that were determined by using acid oil model, however, the lipase was unstable and was not durable for repeated use. The inactivation of the lipase was successfully avoided by addition of excess amounts of methanol (MeOH) in the first-step reaction, and by addition of vegetable oil and glycerol in the second-step reaction. Hence, the first-step reaction was conducted by shaking a mixture of 66 wt% acid oil (77.9 wt% FFAs, 10.8 wt% acylglycerols) and 34 wt% MeOH with 1 wt% immobilized lipase, to convert FFAs to their methyl esters. The second-step reaction was performed by shaking a mixture of 52.3 wt% dehydrated first-step product (79.7 wt% FAMEs, 9.7 wt% acylglycerols), 42.2 wt% rapeseed oil, and 5.5 wt% MeOH using 6 wt% immobilized lipase in the presence of additional 10 wt% glycerol, to convert acylglycerols to FAMEs. The resulting product was composed of 91.1 wt% FAMEs, 0.6 wt% FFAs, 0.8 wt% triacylglycerols, 2.3 wt% diacylglycerols, and 5.2 wt% other compounds. Even though each step of reaction was repeated every 24 h by transferring the immobilized lipase to the fresh substrate mixture, the composition was maintained for >100 cycles.     

印楝素与脂肪酸甲酯联合使用对豆蚜的防治效果

本文对新疆博州豇豆豆蚜Aphis craccivora (Koch)田间消长规律进行调查,研究了0.3%印楝素与脂肪酸甲酯喷雾助剂联合对豆蚜的防治效果,并对豆蚜天敌消退率进行了调查。结果表明,在博州,豆蚜以卵在苦豆子和苜蓿上越冬,3月下旬至4月初开始孵化,5月上中旬出现有翅蚜在杂草上繁殖蔓延,5月中旬开始迁入棉花上危害,6月中旬陆续迁入豇豆上危害,7月上中旬在豇豆上达到危害高峰时期,7月中下旬慢慢迁入苜蓿地,9月中旬出现性蚜,9月下旬-10月中旬在苜蓿和杂草上产卵越冬。施药后1 d,20%啶虫脒可湿性粉剂1 000倍液对豆蚜的防效最高,达到82.91%; 施药后3 d,20%啶虫脒可湿性粉剂1 000倍液防效仍最高为97.92%;施药后7 d,0.3%印楝素乳油60 mL/667m2+脂肪酸甲酯喷雾助剂1 000倍液防效达97.38%,显著高于其他处理。总体来说,在豇豆豆蚜发生期施用1次0.3%印楝素+脂肪酸喷雾助剂防治豇豆豆蚜,防效好、持效期长,对豇豆及蚜虫天敌安全性较好。     

Physiological responses of Opuntia ficus-indica to growth temperature

The influences of various day/night air temperatures on net CO₂ uptake and nocturnal acid accumulation were determined for Opuntia ficus-indica, complementing previous studies on the water relations and responses to photosynthetically active radiation (PAR) for this widely cultivated cactus. As for other Crassulacean acid metabolism (CAM) plants, net nocturnal CO₂ uptake had a relatively low optimal temperature, ranging from 11°C for plants grown at day/night air temperatures of 10°C/0°C to 23°C at 45°C/35°C. Stomatal opening, which occurred essentially only at night and was measured by changes in water vapor conductance, progressively decreased as the measurement temperature was raised. The CO₂ residual conductance, which describes chlorenchyma properties, had a temperature optimum a few degrees higher than the optimum for net CO₂ uptake at all growth temperatures. Nocturnal CO₂ uptake and acid accumulation summed over the whole night were maximal for growth temperatures near 25°C/15°C, CO₂ uptake decreasing more rapidly than acid accumulation as the growth temperature was raised. At day/night air temperatures that led to substantial nocturnal acid accumulation (25°C/15°C.). 90% saturation of acid accumulation required a higher total daily PAR than at non-optimal growth temperatures (10°C/0°C and 35°C/25°C). Also, the optimal temperature of net CO₂ uptake shifted downward when the plants were under drought conditions at all three growth temperatures tested, possibly reflecting an increased fractional importance of respiration at the higher temperatures during drought. Thus, water status, ambient PAR, and growth temperatures must all be considered when predicting the temperature response of gas exchange for O. ficus-indica and presumably for other CAM plants.     

Effects of long term oral acrylamide administration on alpha naphthyl acetate esterase and acid phosphatase activities in the peripheral blood lymphocytes of rats

ABSTRACT

Acrylamide is an important industrial chemical; it also is formed in starch-rich foodstuffs during baking, frying and roasting. Most acrylamide exposure occurs by ingestion of processed foods. We investigated possible immunotoxic effects of extended administration of low doses of acrylamide in rats. To do this, we measured alpha-naphthyl acetate esterase (ANAE) and acid phosphatase (ACP-ase) activities in peripheral blood lymphocytes. Male and female weanling Wistar rats were administered 2 or 5 mg acrylamide/kg/day in drinking water for 90 days. Peripheral blood was sampled at the end of the administration period. We found ANAE staining in eosinophils and T-lymphocytes, but not in monocytes, platelets, B-lymphocytes and neutrophils. ACP-ase was found in B-lymphocytes. We found a significant reduction of the ratio of ANAE:ACP-ase in lymphocytes of the experimental animals compared to controls. We found no statistically significant differences between the doses or sexes. We found that acrylamide ingested in processed foods might affect the immune system adversely by decreasing the population of mature T- and B-lymphocytes.     

Effects of Feeding Pigs Increasing Levels of C 18:1 Trans Fatty Acids on Fatty Acid Composition of Backfat and Intramuscular Fat as well as Backfat Firmness

Forty Large White pigs were fed from 30kg to 103kg body mass on diets supplemented with 6% of pure high-oleic sunflower oil (HO) or HO plus increasing amounts of partially hydrogenated rape seed oil (HR; 1.85%, 3.70%, 5.55%), containing high levels of j 6 to j 11 C 18:1 trans fatty acid isomers. Increasing dietary C 18: trans fatty acids resulted in a linear increase in C 18:1 trans fatty acids and conjugated linoleic acid (cis-9, trans-11 CLA) in backfat (BF) as well as in neutral lipids (NL) and phospholipids (PL) of M. long. dorsi. Thus, the rate of bioconversion of trans vaccenic acid (TVA) into CLA and incorporation of C 18:1 trans and CLA into pig adipose tissue was not limited up to 25g total C 18:1 trans fatty acids including 3.3g of TVA perkg feed. BF was higher in C 18:1 trans fatty acids and CLA than M. long. dorsi NL and PL. In BF and NL the sum of saturated fatty acids (SFA) increased with increasing dietary amounts of HR, while in PL SFA were reduced. Thus, according to their physical properties, C 18:1 trans fatty acids partly replaced SFA in PL. Firmness of backfat was also significantly increased (P<0.05) with increasing amounts of HR in feed.     

Heat–moisture treatment under mildly acidic conditions alters potato starch physicochemical properties and digestibility

Potato starch was subjected to heat–moisture treatment (HMT; 120 °C, 3 h) under mildly acidic conditions (pH 5, 6, or 6.5 [control]) at moisture levels of 15, 20 or 25%. HMT starches exhibited significantly delayed pasting times and reduced overall paste viscosities, amylose leaching, and granular swelling characteristics relative to native starch, as well as enhanced levels of thermo-stable resistant starch (≈24%). HMT appeared to alter/enhance short-range chain associations (FT-IR) within amorphous and/or crystalline regions of starch granules. However, the extent of physicochemical change and RS enhancement during HMT was most facilitated by a mildly acidic condition (pH 6) at higher treatment moisture levels (20 or 25%). These conditions promoted limited hydrolysis of amylopectin molecules, primarily at α-(1 → 6) branch points, likely enhancing mobility and interaction of starch chains during HMT. Thus, a slightly acidic pH might reduce conditions and/or timeframe needed to impart physicochemical changes and reduced digestibility to potato starch.     

人牙根龋发生中有机质破坏的酶学研究

目的 :了解牙根部有机质破坏的机制。方法 :将健康恒牙根颈 1/ 3牙体硬组织 ,磨制成 38.5～149m组织粉粒作样本 ,乳酸 (p H 4.0和 p H5 .5 )及醋酸 (p H 4.5和 p H5 .5 )溶液预处理后 ,测定钙、总蛋白和胶原含量 ;再经胰酶、胶原酶处理后分析释出的胶原量。结果 :乳酸和醋酸预处理不能降解人牙根部的胶原 ,但采用 p H4.0的乳酸处理牙齿后可以使酶对牙本质胶原的降解量明显增高 ,达 (4 4.0 5± 4.5 0 ) μl/ mg;随 p H升高 ,胰酶和胶原酶对根部牙体组织胶原的降解量明显下降 ,脱矿程度减弱 ,钙释出减少。结论 :酸和酶有协同降解胶原的作用。     

Clinical trials testing cardiovascular benefits of antioxidant supplementation

Self-selected supplementation of vitamin E has been associated with reduced coronary events and atherosclerotic progression, but the evidence from clinical trials is controversial. ASAP was a 6-year randomized trial to study the effect of supplementation with vitamin E plus slow-release vitamin C on carotid atherosclerotic progression in 520 hypercholesterolemic men and women aged 45-69 years. The supplementation reduced the progression of carotid atherosclerosis by 26% ( P =0.014), by 33% ( P =0.024) in men and 14% (not significant) in women. The effect was larger in subjects with low baseline vitamin C or atherosclerotic plaques. In the Harvard IVUS trial, the combined supplementation with vitamins E and C significantly inhibited the progression of coronary atherosclerosis in one year. These data confirm that the supplementation with a combination of vitamins E and C can retard atherosclerotic progression. The findings of completed trials testing the effect on cardiovascular events are less consistent. The major on-going clinical trials include the SU.VI.MAX, WHS, WACS and WAVE studies. These involve in total over 80,000 subjects, who are treated with antioxidative supplements for years. The results of these studies will become available during 2003-2006. They may provide the necessary additional information concerning the effect of antioxidants on cardiovascular events.