内标法同时测定挥发性脂肪酸和乳酸的方法探究

选用巴豆酸作为内标物,以内标标准曲线法定量,探讨无需任何前处理便能同时测定挥发性脂肪酸和乳酸的最佳色谱条件。用HP-INNOWAX(19091N-133)毛细管柱,以高纯氮作为载气,用氢火焰离子化检测器对挥发性脂肪酸和乳酸进行测定。结果表明:其理想检测条件为载气总压力160kPa,气化室温度250℃,检测室温度270℃,柱温采用程序升温法,初始温度120℃,然后以10℃/min升温速率升至220℃,保持2min。     

Spontaneous postharvest fermentation of açai (Euterpe oleracea) fruit

Açai (Euterpe oleracea) fruit (EOF) are widely commercialized in the Brazilian Amazon. These fruit contain a high bacterial load and are transported on boards stowed inside or outside the holds of small boats. In this context, postharvest parameters were assessed under conditions that simulated these two methods of EOF transport: stowage in closed polystyrene boxes, simulating the inside of cargo holds, i.e., transport in a closed system; and open baskets, simulating transport in an open environment, i.e., transport in the prow or bow of the boat. EOF suffered spontaneous fermentation of alcoholic, acetic, and lactic types in the closed system, which is the most common type of transportation of this fruit. In the closed system, there was a predominance of lactic acid bacteria over acetic acid bacteria, with 82% and 95% of the initial content of d-glucose and d-fructose being consumed, respectively, after 27 h of experiment. The weight loss reached 1.7% and there was a logarithmic decrease of the major phenolic compounds of the fruit in the closed system, with losses of 78% of cyanidin-3-rutinoside, 88% of cyanidin-3-glucoside, 78% of homorientin, and 72% of orientin after 27 h, which was higher than in the open system (58%, 66%, 73% and 62%, respectively). Analyses on EOF stowed in a closed system indicated that the respiratory rate was characteristic of a non-climacteric fruit, i.e., it showed a logarithmic decay in the production of CO₂ (R² = 0.995; P < 0.05). Thus, transport in a closed system results in more drastic nutritional and functional changes on EOF than when transport is carried out in an open system, suggesting that transportation in continuous aerobic conditions and a short period of time between picking and processing are preferable.     

Varietal differences in phenolic content and astringency in skin and flesh of hardy kiwifruit resources in Japan

Varietal differences in the total phenolic content and astringency in the skin and flesh were determined among the cultivars and local collections of hardy kiwifruit with a ploidy variance found in Japan. The average values of the total phenolic content in the skin and flesh were 2.66 and 0.18 g 100 g⁻¹ FW, respectively. There were large varietal differences in the total phenolic content in the skin in the range of 1.3–5.0 g 100 g⁻¹ FW. Kochi (tetraploid), while Gassan and ‘Mitsuko’ (hexaploid) contained a larger amount of total phenolics. High astringency was found in Gassan, ‘Mitsuko’ and ‘Hoko’ (hexaploids) and Kochi. HPLC analysis showed that the major components of phenolics in the flesh were (+)-catechin, chlorogenic acid, rutin, (−)-epicatechin and quercetin.     

Evaluation of Streptocephalus dichotomus nauplii as a larval diet for freshwater prawn Macrobrachium rosenbergii

This study was performed to assess the nutritional value of Streptocephalus dichotomus nauplii and compared with standard larval diet and parthenogenetic strain of Artemia nauplii. The effectiveness of live feed was determined by feeding freshwater prawn Macrobrachium rosenbergii postlarvae. Results on the growth rate, weight gain, survival, fatty acid and amino acid composition show a significant variation between the dietary treatments. Mean larval growth was significantly different ( P  < 0.001) between control diet (13.5 ± 0.5 mm) and live feeds ( Streptocephalus nauplii; 18.4 ± 0.5 mm and Artemia nauplii 18.7 ± 0.2 mm). The weight of larvae-fed Streptocephalus (41.1 ± 1.44 mg) and Artemia nauplii (41.7 ± 0.2 mg) was not significantly different; however, treatment with live feeds was significantly higher than the control (16.3 ± 0.5 mg) ( P  < 0.001). Proximate composition on the fairy shrimp reveals that they are rich in protein, lipid, essential amino acids (EAA) and essential fatty acids (EFA). The polyenoic unsaturated fatty acid (18 : 2 n-6 and 18 : 3 n-3) and highly unsaturated fatty acid (20 : 4 n-3 and 20 : 5 n-3) show a dramatic increase in larval tissue relative to its proportional composition in the live diets. Amino acid composition in the live feeds, Streptocephalus and Artemia nauplii, perfectly reflects on the amino acid proportions in the larvae-fed diets which confirm its utilization.     

印度Leh地区沙棘叶中脂肪酸的含量

本文用气相色谱仪分析了印度Leh地区沙棘叶油中种脂肪酸的含量，结果显示：该地区沙棘叶油中富含硬脂酸，其值可以达到13．853％，山嵛酸13．938％，亚油酸7．579％，掬焦油酸6．638％，十八稀酸4．622％。     

Use of differently enriched rotifers,Brachionus plicatilis,during larviculture of haddock,Melanogrammus aeglefinus: effects on early growth,survival and body lipid composition

We evaluated the effects of enriched rotifers on growth, survival and on the lipid composition of haddock larvae. The treatments tested were (1) AlgaMac 2000^®, (2) AquaGrow^® Advantage and (3) Pavlova sp. paste and AlgaMac 2000^®. The treatments did not influence larval growth rate throughout the experimental period (P = 0.70). Larvae from all treatments grew approximately 8% of their dry weight per day between 1 and 29 days post hatch (dph). Treatment 3 resulted in the best survival, estimated to be 3 on a scale from 0 to 5, whereas for the two other groups the survival estimates were 0 and 2. Rotifers from treatment 1 had low sterol concentrations, high eicosapentaenoic acid/arachidonic acid ratio and their feeding resulted in high larval mortality. Rotifers enriched with Pavlova sp. had the lowest proportions of the sum of saturated fatty acids, docosahexaenoic acid and sum of ω3 and the highest proportions of the sum of monounsaturated fatty acids (ΣMUFA). This was partially reflected in larvae from treatment 3 in that they had the highest proportions of ΣMUFA and the lowest proportions of Σω3 (P < 0.0001 for both analyses). In addition, these larvae had the highest and lowest ΣC₂₀ and ΣC₂₂ polyunsaturated fatty acids (PUFA) respectively (P < 0.0001 for both analyses). We suggest that more research with ω3 and ω6 PUFA can lead to improvements in the rearing of haddock larvae produced in hatcheries.     

In vitro analyses for predicting standardised ileal digestibility of protein and amino acids in actual batches of feedstuffs and diets for pigs

In vitro digestibility analyses of feedstuffs and diets are integrated in the new Danish feed evaluation system for pigs. This system is based on potential physiological energy and standardised digestible amino acids. For characterisation of the energy value of actual batches of feedstuffs and complete diets for pigs, two different in vitro methods have been developed and proved to analyse precisely the digestibility of organic matter at faecal, as well as at ileal, level in the pigs. For characterisation of the protein value in the diet, table values for standardised digestibility of amino acids from the individual feedstuffs are used for calculation of their contribution to the amino acid recommendations for the specific pig category. The results in the present paper indicate that in vitro analyses for digestibility of crude protein in feedstuffs are a reliable tool for calculation of standardised ileal digestibility of the individual amino acids. Thus, the results may question the need for future experiments with surgically modified pigs for analysing ileal digestibility of amino acids in protein sources. Alternatively, in vitro digestibility analyses appear to have a general potential for a precise evaluation of amino acid digestibility in actual batches of feedstuffs and pig diets.     

假地豆响应缺磷胁迫的代谢衍生物分析

为探究假地豆（Desmodium heterocarpon）对缺磷胁迫的生理和代谢响应,本研究通过水培试验,分析了正常供磷（+P处理）和缺磷（-P处理）对假地豆生长及代谢物积累的影响。结果表明：缺磷胁迫降低了假地豆地上部干重和磷含量,但促进了根系生长。随后,代谢组共检测到假地豆叶片和根系的267个代谢物,可被分为12类。其中,叶片和根系的缺磷胁迫差异累积代谢物（DAMs）均为79个。缺磷处理导致假地豆叶片和根系的原花青素、槲皮素及其衍生物的积累显著增加,而2'-脱氧腺苷5'-单磷酸（dAMP）的积累显著减少。此外,缺磷处理使根系的8个有机酸和4个糖及醇类的积累显著增加。综上,假地豆通过促进根系生长和调整代谢物积累来提高对缺磷胁迫的适应性。本研究将为进一步解析假地豆适应缺磷胁迫的机理提供理论参考。