| Objective: To observe different components of three kinds of peanut protein powders and their effects on nutritional and physiological functions of growing rats. The three kinds of peanut protein were low-temperature peanut protein powder (LTP, processed at temperature under 65℃, low degree denaturalized) , middle-temperature peanut protein powder (MTP, processed at temperature under 120℃,middle degree denaturalized) and traditional high-temperature peanut protein powder (HTP, processed at temperature over 160℃, high degree denaturalized). Then the further experiment was carried out to observe the effects of LTP on lipids metabolism of rats model that fed with high-cholesterol diets to provide scientific and rational evidences for exploitation of peanut protein.Methods: The study was divided into three steps:1. Three kinds of peanut protein were analyzed to observe differences of their components (including main nutriments, mineral and trace elements and amino acids) to provide basis for functional analysis.2. The semi-synthetic diets were prepared with the three kinds of peanut protein and compared with casein. Growing rats were pair fed for 30 days and functional and physiological functions were observed with metabolism technology.3. Compared with normal rats diet, rats were induced by high-cholesterol diet for 30 days to establish the hyperlipidemic models. At the same time, they were force fed (10ml/Kg) with two different doses (0.2g/ml and 0.4g/ml) of LTP liquor divided every day to observe effects of LTP on the metabolism of lipids.Results:1. Three kinds of peanut protein powders were different on their components.⑴LTP was the highest levels in fattiness (11.4%) , protein (56.6%) and its energy. On the contrary, HTP was lowest levels in fattiness (0.7%), protein (48.5%) and energy. Compared with LTP, they went down about 93% and 14% respectively. ⑵LTP and MTP had similar levels in mineral and trace elements content. The content of copper, iron, manganese, calcium and sodium of HTP were higher than those of LTP and MTP. The Fe and Na content of HTP were respectively 11.1 times and 3.5 times as high as that of LTP.⑶Peanut protein contains all of 9 kinds of essencial aminl acid. Most kinds of amino acids were similar in LTP and MTP and almost all of them were the lowest level in HTP. The first limiting amino acid in LTP was Met (0.08g/100g, AAS, 0.23) and it's Lys in MTP (AAS, 0.25) and HTP (AAS, 0.15).⑷Most kinds of amino acids in three peanut protein powders were lower than casein. Nevertheless, the contents of Arginine (Arg), Glycine (Gly) and Proline (Pro) of three peanut protein powders were all higher than those of casein. LTP had the highest levels of Arg (6.38g/100g) and Gly (3.05g/100g). They were 2.13 times and 2.16 times as high as levels of casein (2.99g/100g and 1.41g/100g) respectively.2. Three peanut protein powders had different effects on eight aspects of animal experiment for studying nutritional and physiological functions:⑴On growing aspect, LTP and MTP had obvious advantages on upgrowth state, translation rate of food, nitrogen balance and absorption rate compared with HTP, although they were not as good as casein (P<0.05).⑵About the protein nutritional value indexes, Casein had the highest level on digestibility and protein efficiency ratio (PER)(P<0.05). MTP had the best level on the net protein utilization (NPU). HTP was the worst level on digestibility, PER and NPU (P<0.05).⑶On aspect of protein nutrional state in vivo, LTP was as good as Casein in nutritional evaluations in vivo such as total protein (TP), albumin (ALB) and transferring (TRF) in serum (P>0.05). HTP was the lowest level in all the three indexes. TRF (20.69μmol/L) went down about 39% compared with the casein group rats (33.48μmol/L) and TP and ALB were decresed about 9.9% and 8.4% respectively (P<0.05).⑷On metablism of mineral and trace elements aspect, Zn and Fe contents in liver and Zn content in kidney significantly increased in all three peanut protein groups rats (P<0.05). The apparent absorption rate (AAR) and apparent retention rate (ARR) of Cu in LTP group rats were increased distinctly. The absorption, storage and utilization of all six kinds of mineral elements that observed in this study were obviously decreased in HTP group rats. ⑸On aspect of intestine trash, all three peanut protein powders can increase feces weight and its hydrated ratio (P<0.05). They were 1.49 times and 1.28 times of LTP group rats as high as those in casein group rats repectively. The feces weight and its hydrated ratio of HTP group rats were about 27% and 1.74times higher than those of casein group rats. It indicated that peanut protein can dilute intestine trash so as to accelerate its excretion.⑹On aspect of lipids, compared with casein diet, all kinds of peanut protein diet could significantly increase high-density lipoprotein cholesterol (HDL-C) concentration in serum (27.5% to 40.9%) (P<0.05). The LTP also can significantly depress the serum low-density lipoprotein cholesterol (LDL-C) (0.14mmol/L) and ttriglycerides (TG) (0.48mmol/L) level about 30% and 17 % compared with casein group ( 0.20mmol/L and 0.58 mmol/L) (P<0.05). Its athrosclerosis index (AI) went down 36.1%. It showed that LTP had the most effective functions on lipids metabolism in vivo.⑺On aspect of blood routine indexes and serum biochemical indexes, peanut protein can lower rats'serum glucose (GLU) about 21% to 28% and platelet (PLT) level about 10% to 33% than those in casein group. Serum GLU (7.54mmol/L) of LTP group rats was 28% lower than that of casein group rats (10.47mmol/L). So LTP had the most effective regulation on GLU. The mean corpusular hemoglobin concentration (MCHC) (391.6g/L) level and mean corpusular volume (MCV) (53.2fl) of HTP group rats went down respectively about 39% and 6.2% compared with the casein group rats (33.48μmol/L and 56.72fl) (P<0.05). With the combination of the TRF result, they indicated that HTP group rats might have potential dangers of anaemia induced by lack of TRF.⑻On the antioxidation aspect, LTP can improve the activities of SOD (90.87U/ml) and GSH-Px (165.75U/ml) in serum about 11.7% and 42.2% compared with casein group rats (81.34U/ml and 116.6U/ml). HTP also can heighten the activities of GSH-Px (168.38U/ml) in serum about 44.5% and SOD in kidney about 29%. So both of them could enhance the antioxidative activities in vivo.3.LTP had potent effects on regulating blood lipids in hyperlipidemic rats. The operation ways were as follows:⑴To reduce the triglyceride (TG) level in serum (0.60mmol/L) and liver (16.4mmol/L) obviously (0.66mmol/L and 19.9mmol/L in hyperlipidemic model group rats )(P<0.05)⑵To regulate HDL-C (1.33mmol/L) and LDL-C (0.91mmol/L) levels in serum (1.12mmol/L and 1.37mmol/L in hyperlipidemic model group rats) so as to enhance the transportation of lipids from blood and ambient tissues to liver and avoid accumulation of cholesterol in blood vessels.⑶To decrease the production of malondialdehyde (MDA) in serum (3.13nmol/ml) and liver (1.41nmol/mgPr) and lipofusion (LF) in brain (2.14μg/g) through antioxidation (3.56nmol/ml, 2.10nmol/mgPr and 8.97μg/g in hyperlipidemic model group rats) so as to avoid accumulation of lipids in liver cells.⑷To enhance activities of liportein lipase (LPL) in liver (P<0.05) so as to accelerate the translation of TG. But it had no obvious effects on hepatic endothelail lipase (HL).⑸To increase content of bile acid in feces so as to hasten the transform and eduction of cholesterol indirectly.Conclusion:Peanut protein can suffice the growing demands of rats although its growing state, ture digestibility, efficiency ratio(PER) are inferior than casein. All three peanut protein powders had founctions to reduce blood lipids, GLU and PLT level and to hasten the excretion of enteric trash compared with casein. Moreover, they also have advantages on enhancing the activities of SOD and GSH-Px in serum.In the three peanut protein powders, LTP and MTP had similar nutrional components, absorption rate and nutrional values in vivo. However the LTP had obvious advantages on regulation of lipids , GLU and antioxidation. HTP was the lowest level in most nutritional aspects. That is to say that the low temperature defatting process had more benefits for peanut protein to express its nutritional functions.
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