新疆脱脂葡萄籽天然蛋白的研究现状

综述了新疆脱脂葡萄籽的基本成分,脱脂葡萄籽天然蛋白的分离方法、功能性研究以及改性技术研究。     

Effect of incubation temperature on carbohydrate digestion in important teleosts for aquaculture

The activity and capacity (activity × tissue weight) of digestive carbohydrases (total carbohydrase, α‐glucosidase, α‐amylase) was examined in vitro under a range of (more realistic) incubation temperatures (5, 18 and 25°C) and pH (7.6) more likely to be encountered during rearing, along the digestive tract of important teleost species for aquaculture (Dicentrarchus labrax, Sparus aurata, Oreochromis aureus, Oncorhynchus mykiss and Salmo salar). Results indicate, among other things, an overestimation of digestive carbohydrase levels when performing assays at 37°C, a different effect of temperature on digestive enzyme performance along the digestive tract of examined species, and the increased importance of α‐glucosidase towards carbohydrate digestion. Implications regarding the capacity of each species for carbohydrate digestion in nature, as well as feed manufacturing, are discussed.     

Effect of a carbohydrase admixture in growing pigs fed wheat-based diets in thermoneutral and heat stress conditions

The efficacy of exogenous carbohydrases in pig diets has been suggested to depend on enzyme activity and dietary fiber composition, but recent evidence suggests other factors such as ambient temperature might be important as well. Therefore, we investigated the effect of heat stress (HS) on the efficacy of a multienzyme carbohydrase blend in growing pigs. Ninety-six (barrows: gilts; 1:1) growing pigs with initial body weight (BW) of 20.15 ± 0.18 kg were randomly assigned to six treatments, with eight replicates of two pigs per pen in a 3 × 2 factorial arrangement: three levels of carbohydrase (0, 1X, or 2X) at two environmental temperatures (20 °C or cyclical 28 °C nighttime and 35 °C day time). The 1X dose (50 g/tonne) provided 1,250 viscosimetry unit (visco-units) endo-β-1,4-xylanase, 4,600 units α-l-arabinofuranosidase and 860 visco-units endo-1,3(4)-β-glucanase per kilogram of feed. Pigs were fed ad libitum for 28 d and 1 pig per pen was sacrificed on day 28. There was no enzyme × temperature interaction on any response criteria; thus, only main effects are reported. Enzyme treatment quadratically increased (P < 0.05) BW on day 28, average daily gain (ADG) (P < 0.05), and average daily feed intake (ADFI) (P < 0.05) with the 1X level being highest. HS reduced the BW at day 14 (P < 0.01) and day 28 (P < 0.01), ADG (P < 0.01), and ADFI (P<0.001). There was a trend of increased feed efficiency (G:F) (P < 0.1) in the HS pigs. HS increased apparent jejunal digestibility of energy (P < 0.05) and apparent ileal digestibility of calcium (P < 0.01). At day 1, HS reduced serum glucose (P < 0.001) but increased nonesterified fatty acid (P < 0.01). In the jejunum, there was a trend of increased villi height by carbohydrases (P < 0.1), whereas HS reduced villi height (P < 0.05). HS increased the jejunal mRNA abundance of IL1β in the jejunum (P < 0.001). There was a trend for a reduction in ileal MUC2 (P < 0.1) and occludin (P < 0.1) by HS, and a trend for increased PEPT1 (P < 0.1). There was no effect of HS on alpha diversity and beta diversity of the fecal microbiome, but there was an increase in the abundance of pathogenic bacteria in the HS group. In conclusion, HS did not alter the efficacy of carbohydrases. This suggests that carbohydrases and HS modulate pig performance independently.     

Effects of extrusion and supplementation of exogenous enzymes to diets containing Chinese storage brown rice on the carbohydrase activity in the digestive tract of piglets

Two experiments were conducted to study the effects of extrusion of Chinese storage brown rice and of exogenous enzymes supplementation to diets containing Chinese storage brown rice on the carbohydrase activity in digestive tract of piglets. In Experiment 1, 96 weaned piglets [initially 6.95 ± 0.05 kg body weight (BW)] were used in a 2 × 2 factorial design, the animals were fed the diets containing extruded Chinese storage brown rice or non‐treated Chinese storage brown rice and supplemented with or without exogenous enzymes. Each treatment had six replicate pens and four piglets in each pen. The results demonstrated that extrusion significantly increased (p < 0.05) the activity of duodenal maltase after 14 days of treatment and glucoamylase after 28 days of treatment, jejunal lactase, maltase, isomaltase, sucrase and α‐amylase after 28 days of treatment, and jejunal α‐amylase after 14 days of treatment; enzyme supplementation positively influenced (p < 0.05) the activity of pancreatic α‐amylase after 14 and 28 days of treatment, pancreatic glucoamylase after 28 days of treatment and ileal trehalase after 14 days of treatment. Similarly, interaction between extrusion and enzyme addition existed after 14 days of treatment on the activity of pancreatic α‐amylase and duodenal maltase and on the activity of duodenal glucoamylase and isomaltase, jejunal α‐amylase, lactase, maltase, isomaltase and jejunal α‐amylase after 28 days of treatment. In Experiment 2, six piglets (initially 21 ± 1.85 kg BW) fitted with ileal ‘T’‐cannulas in a 6 × 6 Latin Square Design were used to study the effects of extrusion and addition of exogenous enzymes on ileal carbohydrase activity and nutrients digestibility. The results showed that exogenous enzymes significantly (p < 0.05) increased ileal α‐amylase, glucoamylase and trehalase activity. The interaction between extrusion and enzyme supplementation had positive effect (p < 0.05) on the ileal lactase, cellobiase and sucrase activity.     

Digestibility of canola protein products derived from the physical, enzymatic and chemical processing of commercial canola meal in rainbow trout Oncorhynchus mykiss (Walbaum) held in fresh water

This study was undertaken to assess the relative importance of nutrient composition and levels of antinutritional factors present in various canola protein products derived from the processing of commercial canola meal (CCM) on digestibility in rainbow trout held in 9.9–11°C fresh water. Laboratory sieving of CCM (SCM) reduced levels of crude fibre, cellulose and hemicellulose by 31.6%, 16.6% and 56.4%, respectively. Aqueous methanol–ammonia washing of sieved canola meal (ACM) increased neutral detergent fibre (NDF, insoluble dietary fibre) and phytate, and dramatically decreased levels of total glucosinolates (> 88%) and phenolic compounds (≈ 59%) relative to CCM. Further treatment of ACM with phytase in acidified (pH 5.0) aqueous media (PCM), followed by filtration, increased levels of crude protein, crude fibre and NDF, and decreased levels of phytate (33%), phenolic compounds (81%) and glucosinolates (below detection limit) relative to CCM. Additional treatment of PCM with carbohydrase enzymes (SP-249 and/or Alpha Gal, an oligosaccharide-degrading enzyme) further elevated levels of NDF, cellulose, protein (SP-249 only) and indispensable amino acids (SP-249/Alpha Gal), and concurrently decreased levels of phytate relative to PCM. An industrial source of canola protein isolate (CPI), produced by first extracting CCM with aqueous salt solution and then recovering the protein fraction, had the best nutrient composition and lowest levels of the antinutritional factors mentioned above. The processing protocols had slight or marked negative effects (ACM and SP-249/Alpha Gal) on apparent dry matter digestibility. Protein digestibility coefficients were unaltered in the laboratory-processed products, except for the products treated with SP-249 and SP-249/Alpha-Gal. In these cases, the protein digestibility coefficients (77.4% and 79.5%) were significantly below that found for CCM (88.1%). With two of the treatments, ACM and SP-249/Alpha-Gal, processing depressed DE. In contrast, the DE level in CPI (20.6 MJ kg^?1) and the digestibility coefficients for dry matter (77.1%) and protein (97.6%) were high. We conclude that high levels of fibre, either alone or together with phytate, have the greatest adverse effects on the digestibility of canola protein products for rainbow trout. The high digestibility of CPI and its low content of antinutritional factors may also enable this protein product to be an excellent substitute for premium quality fish meal in diets for salmonids.     

Characterization of digestive enzymes protease and alpha‐amylase activities in the thick‐lipped grey mullet (Chelon labrosus,Risso 1827)

Activities of pepsin, trypsin, chymotrypsin, alpha‐amylase and lipase, as well as their optima and stability to pH and temperature, were determined in digestive extracts of thick‐lipped grey mullet, Chelon labrosus, of three different sizes: Group 1 (45.2 ± 3.0 g), Group 2 (180.9 ± 4.2 g), and Group 3 (328.5 ± 43.3 g). SDS‐PAGE zymograms were also used to assess the role of serine proteases in the digestive tract of C. labrosus. On the other hand, possible changes in the digestive enzyme profile of C. labrosus during development were observed, with a comparatively lower pepsin activity, higher activities of alkaline proteases and alpha‐amylase and no lipase activity recorded in pre‐adult specimens. It is suggested that these variations are linked to the changes in diet composition with age, moving from a partly carnivorous to a more herbivorous feeding habit.