论烹饪过程中对食物营养素的保护

人们的日常生活离不开烹饪,烹饪过程中保护好食物的营养素,是制作精美菜肴的基础,才能发挥出食物的真正营养价值。如果在烹饪过程中破坏了食物的营养成分,会影响到食品的质量。本文主要论述烹调过程中对食物营养素的保护需注意的问题。

Comparative study of the nutritional composition and toxic elements of farmed and wild Chanodichthys mongolicus

Information of the difference in quality between farmed and wild fish is central to better ensuring fish products produced in aquaculture meet regulatory and consumer requirements. Proximate composition, amino acid and fatty acid profiles, and toxic elements contents of fanned and wild Chanodichthys mongolicus were established and compared. Significantly higher crude protein content while lower moisture content in farmed fish compared to wild fish were observed （P〈0.05）. The percentages of total amino acids （TAA）, total essential amino acids （TEAA）, total non-essential amino acids （TNEAA） and total delicious amino acids （TDAA） in farmed fish were all significantly higher than those in the wild equivalent （P〈0.05）. Compared to the FAO/WHO recommended reference values, the ratios of TEAA/ TAA （39.84%o-40.33%） were comparable to 40% and TEAA / TNEAA （66.22%-67.60%） were above 60%. Fatty acid profiles in both farmed and wild C. mongolicus were dominated by monounsaturated fatty acid （MUFA）, with farmed fish contained much more MUFA content compared to wild counterpart （P〈0.05）. Notably, wild fish exhibited significantly higher levels of total polyunsaturated fatty acid （PUFA） including eicosapentaenoic acid （EPA） and docosahexaenoic acid （DHA） than fanned fish （P〈0.05）. The EPA （C20：503） and linoleic acid （C18：206） were the predominant PUFA in wild and farmed C. mongolicus, respectively. Moreover, farmed fish displayed an overall lower toxic element levels （As, Cd, Pb and Hg） in comparison with wild fish, and both were far lower than the established limit standard. In conclusion, our results suggest that the nutritional quality of fanned C. mongolicus was inferior to their wild counterpart with respect to fatty acids nutrition, and therefore further studies should focus on the improving C. mongolicus diet in order to enhance the overall nutritional composition.

Effects of nutrients and light intensity on the growth and biochemical composition of a marine microalga Odontella aurita

Algal biotechnology has advanced greatly in the past three decades. Many microalgae are now cultivated to produce bioactive substances. Odontella aurita is a marine diatom industrially cultured in outdoor open ponds and used for human nutrition. For the first time, we have systematically investigated the effects of culture conditions in cylindrical glass columns and fiat-plate photobioreactors, including nutrients （nitrogen, phosphorus, silicon, and sulfur）, light intensity and light path, on O. aurita cell growth and biochemical composition （protein, carbohydrate, β-1,3-glucan, lipids, and ash）. The optimal medium for photoautotrophic cultivation of O. aurita contained 17.65 mmol/L nitrogen, 1.09 mmol/L phosphorus, 0.42 mmol/L silicon, and 24.51 mmol/L sulfur, yielding a maximum biomass production of 6.1-6.8 g/L and 6.7-7.8 g/L under low and high light, respectively. Scale-up experiments were conducted with fiat-plate photobioreactors using different light-paths, indicating that a short light path was more suitable for biomass production of O. aurita. Analyses of biochemical composition showed that protein content decreased while carbohydrate （mainly composed of 15-1,3-glucan） increased remarkably to about 50% of dry weight during the entire culture period. The highest lipid content （19.7% of dry weight） was obtained under 0.11 mmol/L silicon and high light conditions at harvest time. Fatty acid profiles revealed that 80% were Cx4, C^6, and C20, while arachidonic acid and eicosapentaenoic acid （EPA） accounted for 1.6%-5.6% and 9%-20% of total fatty acids, respectively. High biomass production and characteristic biochemical composition profiles make O. aurita a promising microalga for the production ofbioactive components, such as EPA and D-1,3-glucan.

Planting Performance of Several Elephant Grass Species in Northern Guangxi Zhuang Autonomous Region

This study aimed to screen suitable species of Pennisetum purpureum for planting in northern Guangxi Zhuang Autonomous Region. During 2012-2014, a comparative field trial was carried out in Lingyun County of Baise City in northern Guangxi to compare plant height, yield, stem-leaf ratio and nutrient composition am-ong Pennisetum purpureum Schumab cv. Purple, P. purpureum Schum cv. Guimin and P. purpureum Rich ＆#215; P. americana King grass cv. Reyan No.4. The results in-dicated that average annual fresh yield of P. purpureum Schumab cv. Purple reached 141.4 t/hm2, which was 2.3 t/hm^2 higher than that of P. purpureum_Rich×P. americana_King grass cv. Reyan No.4; both average annual fresh yield of these two species was lower than that of P. purpureum Schum cv. Guimin. Stem-leaf ratio of P. purpureum Schumab cv. Purple was the lowest （1.17）, which was 17.8% lower compared with P. purpureum Schum cv. Guimin, with significant differences （P〈0.05）, indicating that P. purpureum Schumab cv. Purple had more leaves. Crude protein content of P. purpureum_Schumab cv. Purple was slightly lower than that of P. purpureum Rich×P. americana_King grass cv. Reyan No.4, while P. purpureum Schumab cv. Purple was superior to P. purpureum Schum cv. Guimin and P. pur-pureum Rich ×P. americana_King grass cv. Reyan No.4 in other indicators. Specifi-cal y, P. purpureum Schumab cv. Purple contained 26.6% of dry matter, 39.1% of nitrogen-free extract and 2.9% of crude fat.

Effects of glutamine-containing total parenteral nutrition on phagocytic activity and anabolic hormone response in rats undergoing gastrectomy

AIM: To investigate the effect of glutamine (Gln)-containing parenteral nutrition on phagocytic activity and to elucidate the possible roles of Gln in the secretion of anabolic hormones and nitrogen balance in rats undergoing a gastrectomy. METHODS: Rats with an internal jugular catheter were divided into 2 experimental groups and received total parenteral nutrition (TPN). The TPN solutions were isonitrogenous and identical in nutrient compositions except for differences in amino acid content. One group received conventional TPN (control), and in the other group, 25% of the total amino acid nitrogen was replaced with Gin. After receiving TPN for 3 d, one-third of the rats in each experimental group were sacrificed as the baseline group. The remaining rats underwent a partial gastrectomy and were killed 1 and 3 d, respectively, after surgery. Plasma, peritoneal lavage fluid (PLF), and urine samples were collected for further analysis. RESULTS: The Gln group had fewer nitrogen losses 1 and 2 d after surgery (d1, 16.6±242.5 vs-233.4±205.9 mg/d, d2, 31.8±238.8 vs-253.4±184.6 mg/d, P<0.05). There were no differences in plasma growth hormone (GH) and insulin-like growth factor-1 levels between the 2 groups before or after surgery. The phagocytic activity of peritoneal macrophages was higher in the Gln group than in the control group 1 d after surgery (A 1185±931 vs323±201, P<0.05). There were no differences in the phagocytic activities of blood polymorphonuclear neutrophils between the 2 groups at the baseline or on the postoperative days. No significant differences in interleukin-1β or interleukin-6 concentrations in PLF were observed between the 2 groups. However, tumor necrosis factor-α level in PLF was significantly lower in the Gln group than in the control group on postoperative d 3. CONCLUSION: TPN supplemented with Gln can improve the nitrogen balance, and enhance macrophage phagocytic activity at the site of injury. However, Gin supplementation has no effect on phagocytic cell activity in the systemic circulation, GH and insulin-like growth factor-1 might not be responsible for attenuating nitrogen losses in rats with a partial gastrectomy.

Macronutrient Composition and Digestibility of Extruded and Fermented Soya Protein Products

The macronutrient composition and in vitro protein digestibility of extruded fermented and unfermented extruded soya protein products （low, medium and high moisture）, raw and fermented soya meal and soya kernel were studied. The protein content （g/100g soya dry weight） ranged from 38.20 to 62.98 with the highest content in the high moisture extruded protein product fermented with 5 mL inoculum of Bacillus natto. Contents of carbohydrates ranged from 14.77 to 29.08 while those of crude fibre, fat and ash were generally low. Fermentation better improved protein digestibility in the raw soya meal and kernel than in the unfermented extruded and extruded fermented products. SDS-PAGE electrophoresis revealed some degradation of the protein sub units of fermented samples.

Multi-micronutrient Fortified Beverage Delivered through the School-Based System Improved Iron Status and Test Scores of Children

Fortifying commonly consumed foods and beverages offers a great opportunity of filling the nutrient gap between actual and the needed nutrient intakes of young children. Ready-to-drink beverage as a vehicle for fortification is easy to administer, more consistent and least obstructive, because it can be consumed without further processing/cooking. This study aimed to evaluate the effectiveness of fortified beverage on the improving of iron status and school performance test of schoolchildren. About 5,000 schoolchildren aged 6-12 years old from 19 schools in Quirino province, Philippines were invited to participate in the study. Samples of 4,875 children with parental consent were screened for hemoglobin and serum ferritin levels. About 4,495 children had complete participation in the school performance test, which were developed and administered by school supervisors. Children were fed 200 mL ready-to-drink juice fortified with iron, zinc, lysine, vitamins A and C for 120 d. The beverage was delivered through the baseline. At end of the intervention, only 1,050 children had complete data set and the anemia rate reduced from 100% to 60%. Iron deficiency has increased insignificantly from 3.6% to 4.5%. Mean percentage of test scores increased significantly between base and end of the study： English （40% to 60%）, math （35% to 58%） and science （32% to 58%）. In conclusion, consumption of 200 mL fortified juice drink had contributed to the reduction of anemia and increased tests scores of children.

Response of Two Sweet Potato （Ipomoea batatas L. Lam） Varieties Regenerated on Low Cost Tissue Culture Medium

Plant tissue culture continues to be of great interest within the realms of molecular biology, plant breeding and plant health However, different plant cultivars have different culture efficiencies to tissue culture. In this research, the response of two Kenyan sweet potato varieties, KEMB 36 and Tainurey, cultured on a low cost tissue culture medium was evaluated. The low cost medium contained plant nutrients that were obtained from locally available fertilizers. Each conventional Murashige and Skoog （MS） macronutrient was individually substituted with a locally available fertilizer. The conventional source of micronutrients was substituted with Stanes~ Iodized Microfood while sucrose was obtained from table sugar. Performance of the two cultivars was monitored over a period of six weeks. KEMB 36 had a better performance than Tainurey with an average of eight nodes, seven leaves, three roots and height of four centimeters per plantlet indicating genotype-dependent response.

Regulation of carotenoid biosynthesis in fruits

Carotenoids are a class of isoprenoids widely distributed in plants,algae,fungi and bacteria.Carotenoids are essential components for human diet,providing health promoting and nutritional benefits.Fruits are the major source of carotenoids for human consumption.Carotenoid biosynthesis and regulation in fruits are of great importance for development and maintenance of nutritional quality.In recent years,significant progress has been made in understanding the biosynthesis and regulation of carotenoids in tomato and other widely consumed fruits.Carotenoid accumulation in fruits is highly regulated by developmental programs,environmental factors,and metabolic signals at multiple levels.In this review,we highlight recent insights into transcriptional(transcription factor,alternative RNA splicing,epigenetic modification,miRNA),post-transcriptional and hormone regulation of carotenoid biosynthesis in plants,especially in fruits.