【作者】 李劲；

【导师】 张国权；

【作者基本信息】 西北农林科技大学 ， 食品科学， 2008， 硕士

【摘要】 核桃的营养价值丰富,核桃油不饱和脂肪酸含量高。目前核桃制油多以压榨为主,核桃蛋白很难深加工利用。本文以陕西市售核桃为试材,对核桃油水剂法与水酶法工艺条件进行了优化,对两种工艺所得核桃油品质、蛋白粕功能特性进行了比较分析,并对水酶法所得蛋白粕的水解条件及其产物的抗氧化性进行了研究。取得以下研究结果:(1)在水剂法提取核桃油工艺中,磨浆料水比、搅油时间、离心转速对出油率的影响均达极显著。水剂法提取核桃油的适宜工艺条件为:搅油温度25℃、搅油时间4 h、磨浆料水比1:3、离心转速4800 r/min,其出油率可达到72.00%。(2)在水酶法提取核桃油工艺中,搅油温度和搅油时间对出油率的影响最大,酶用量、pH值对出油率的影响较小,搅油温度、搅油时间对出油率的影响显著。水酶法提取核桃油的适宜工艺条件为搅油温度55℃,搅油时间120 min、酶用量17500U/100g料浆、pH值4.5,出油率可达到77.34%。(3)与水剂法提油工艺相比,水酶法提油工艺对于核桃粗蛋白的吸水性、吸油性有明显提高,对粗蛋白的溶解性影响不大,两种粗蛋白的表面功能特性差。(4)水酶法-粗蛋白经充分脱脂后水解1 h即可达到最大水解度的90%以上。桃核粗蛋白酶水解液对·OH自由基、ABTS+自由基、DPPH自由基具有较强清除能力,对超氧阴离子自由基的清除能力不明显。核桃粗蛋白酶水解液的抗氧化能力和水解度之间的没有明显的相关性。(5)在水剂法提取核桃油工艺中,在搅油温度低于核桃蛋白变性温度时,随着温度的升高,出油率降低;在温度高于核桃蛋白变性温度时,出油率随温度升高而增加。在水酶法提取核桃油工艺中,核桃低温贮藏对于水酶法提取核桃油出油率有明显的不利影响;pH值对出油率的影响较大,核桃蛋白的溶解度越小出油率越高。更多还原

【Abstract】 Walnut is well known for its nutrition value. Walnut oil contains large numbers of unsaturated fat acid. At present, walnut oil mostly get from pressure technology, walnut protein is difficult to use. The walnut sold on the shannxi market as test material, the main factors that affected the oil extraction rate are analyzed; researche about technology for aqueous enzymatic extraction based on the process of aqueous extraction; compare the different functional properties of walnut meal get from aqueous enzymatic extraction and aqueous extraction; finally study on the enzymatic hydrolysis of fully defatted walnut meal and the oxidation resistance of enzymatic hydrolysate. The main results and conclusions as follows:1. In the aqueous extraction, the effect of ratio of material to water, stirring time and the effect of centrifugal speed on oil extraction rate reached extremely significant level. The optimum conditions were found as follows: the stirring temperature is 25℃, the stirring time is 4 h, the ratio of material and water is 1:3, the centrifugal rotational speed is 4800 r/min. At this condition the rate of oil extraction is 72.00%.2. In the aqueous enzymatic extraction, the effect of stirring temperature and stirring time on oil extraction rate reached significant level. The optimum conditions were found as follows: dosage of the enzyme 17500U/100g slurry, stirring temperature 55℃, stirring time 3 h, pH 4.5. At this condition the rate of oil extraction is 77.34%.3. The walnut meal get from aqueous enzymatic extraction technology has higher water absorption rate and oil absorption rate than the walnut meal get from aqueous extraction technology. There is no significant difference in protein solubility of two meals. The surface characteristics of two meals are bad.4. The degree of hydrolysis of fully defatted walnut meal get from aqueous enzymatic extraction can go up to 90% of the maximum degree of hydrolysis. The enzymatic hydrolysate had strong activity of scavenging·OH, ABTS+, DPPH and no scavenging activity on superodide anion radical. There is no obvious correlation between hydrolysis degree and antioxidant capacity of enzymatic hydrolysate.5. In the aqueous extraction, when the stirring temperature lower than that of walnut protein denaturation temperature, the oil extraction rate rised with decreasing temperature, when the stirring temperature higher than that of walnut protein denaturation temperature, the oil extraction rate rised with increasing temperature. In the aqueous enzymatic extraction, it is discovered that the oil extraction rate decreased obviously when the walnut was stored at low temperature, the pH value has a great effect on the oil extraction rate, the smaller the solubility of walnut protein, the higher the oil extraction rate.更多还原