原料压榨制油的预处理方式对核桃多肽功能特性和ACE抑制活性的影响

旨在研究原料压榨制油的预处理方式对核桃多肽性质的影响。对核桃仁分别进行未预处理、去衣、焙烤预处理后,进行压榨提油,以提油后的饼为原料,经正己烷脱脂,碱性蛋白酶酶解制备核桃多肽,测定核桃多肽的功能特性和ACE抑制活性。结果表明:与未预处理、焙烤预处理比较,去衣预处理的核桃多肽的持水性(50℃,5.11 g/g)、吸油性(50℃,3.25 g/g)、乳化性(pH 9.0,62.57%)、乳化稳定性(pH 9.0,84.51%)、起泡性(pH 9.0,117.49%)及ACE抑制率(63.04%)最高。综上,以去衣预处理压榨制油后的核桃饼为原料制备的核桃多肽具有良好的功能特性和ACE抑制活性。     

利用海洋微藻生产二十二碳六烯酸的研究进展北大核心CSCD

二十二碳六烯酸(DHA)是一种ω-3系多不饱和脂肪酸,对人体生长发育和健康具有重要作用,但其传统来源并不稳定且会引入鱼腥味,因此积极开发DHA新来源具有重要的研究价值和市场潜力。介绍了DHA的结构、理化性质、功能特性和来源,并从微生物产DHA途径,高产DHA藻种裂壶藻和寇氏隐甲藻的特点、诱变选育种情况、摇瓶培养条件和发酵工艺优化等方面阐述了微生物发酵生产DHA的研究情况。另外,从食用油和乳液两个方面对DHA藻油在食品中的应用情况进行了介绍。目前以裂壶藻和寇氏隐甲藻发酵生产DHA已取得初步成功,可以为现有生产提供理论基础,但有关胞内合成DHA和精准调控实现DHA增产还有待进一步研究。     

酶法辅助制备核桃蛋白的工艺优化及超滤回收核桃蛋白

为提高核桃蛋白得率,分别探索了以碱性蛋白酶、纤维素酶和α-淀粉酶为辅助酶,碱溶酸沉法制备核桃蛋白的工艺,采用超滤工艺回收酸沉废液中核桃蛋白,比较醋酸纤维素(CA)膜、聚醚砜树脂(PES)膜和聚偏氟乙烯(PVDF)膜3种不同超滤膜的回收效率。结果表明,酶法辅助碱溶酸沉法制备核桃蛋白的最佳工艺条件为以纤维素酶为辅助酶、酶解时间60 min、酶解pH 3.6、酶添加量0.5%、酶解温度37℃,在最佳工艺条件下核桃蛋白得率为84.11%。CA膜能显著提高核桃蛋白得率,在原料液质量浓度0.363 mg/mL、原料液温度30℃的条件下,CA膜的截留率可达92.33%,核桃蛋白得率可达87.64%。     

棉籽多肽的制备工艺优化及功能特性

为有效利用棉籽这一优质蛋白质资源,以棉籽蛋白水解度(DH)和水解液感官(色泽,气、滋味)为评价指标,对蛋白酶进行选择,再以棉籽蛋白DH为指标,利用单因素实验及响应面实验对复合蛋白酶水解棉籽蛋白制备棉籽多肽的工艺条件进行优化,并研究了棉籽多肽的氨基酸组成及功能特性。结果表明：选择碱性蛋白酶和风味蛋白酶按质量比2∶1构成复合蛋白酶;最优工艺条件为水解pH 10、水解温度60℃、加酶量6 000 U/g、水解时间90 min,在此条件下棉籽蛋白DH为29.35%;棉籽多肽中有7种必需氨基酸,必需氨基酸总含量达到12.50 mg/100 mg,占氨基酸总量的26.25%;与棉籽蛋白相比,棉籽多肽的吸湿性有较大提升;在20℃时棉籽多肽的吸油性较好;在弱碱性时棉籽多肽的乳化性与乳化稳定性较好;棉籽蛋白DH与棉籽多肽的起泡性呈正相关,与泡沫稳定性呈负相关。采用该工艺制备的棉籽多肽氨基酸含量丰富,具有良好的功能特性。     

两种天然抗氧化剂对稻米油煎炸性能的影响

为选择适合稻米油煎炸的天然抗氧化剂,对茶多酚和迷迭香提取物两种天然抗氧化剂的添加量进行了选择,并测定了稻米油在30 h煎炸过程中理化指标、营养物质以及危害物质的变化。结果表明：茶多酚和迷迭香提取物的最佳添加量均为200 mg/kg,其氧化诱导时间均高于未添加天然抗氧化剂组(1.50 h);煎炸过程中,添加迷迭香提取物的稻米油酸值(KOH)增幅最小(30 h, 0.64 mg/g),极性组分含量达到煎炸油废弃标准(27%)的时间最长(23 h);添加茶多酚的稻米油过氧化值最高值较小(6.12 mmol/kg);煎炸后,添加迷迭香提取物的稻米油α-生育酚(18 h, 17.66%)和谷维素(24 h, 93.24%)的保留率最高;茶多酚可有效减少反式脂肪酸的生成,但迷迭香提取物抑制BaP生成的效果较好;添加天然抗氧化剂可显著提升稻米油脂肪酸的稳定性;两种天然抗氧化剂对稻米油煎炸过程中3-MCPD酯含量的变化影响不显著。综合考虑煎炸效果和成本,迷迭香提取物对提升稻米油煎炸性能更具优势。     

酶法辅助提取、纯化米糠蛋白工艺优化

旨在为米糠副产品的精深加工利用提供指导,利用碱性蛋白酶辅助碱溶酸沉法提取米糠蛋白,并进一步以纤维素酶纯化米糠蛋白,在单因素实验的基础上通过正交实验优化提取、纯化工艺条件。结果表明：米糠蛋白提取的最佳工艺条件为酶解pH 10.5、酶解温度50℃、料液比1∶10、酶解时间120 min、加酶量2.5%,在此条件下米糠蛋白提取率为75.2%;米糠蛋白纯化的最佳工艺条件为酶解温度50℃、酶解pH 5.0、酶解时间60 min、加酶量4%、料液比1∶10,在此条件下米糠蛋白纯度为81.6%,提取率为72.6%。采用此方法可以得到提取率和纯度均较高的米糠蛋白。     

Investigation of hotpot oil based on beef tallow and flavored rapeseed oil in commercial hotpot seasoning

This study aimed to investigate the quality of hotpot oil from various hotpot seasonings. For this, 12 representative hotpot seasonings with beef tallow (BT) and flavored rapeseed oil (FRO) were collected before the hotpot oil was extracted. The oil content, sensory evaluation scores, physiochemical properties, fatty acid composition, harmful substances, and nutrient content of the hotpot oil were subsequently analyzed. The results showed that the oil content of the hotpot seasoning was 38.3%–58.2%. Furthermore, the BT hotpot oils produced better sensory scores (7–8.5), and their oxidative stability (12.08–13.17 h) was higher on average than that of the FRO hotpot oils. Additionally, the FRO hotpot oils had higher contents of unsaturated fatty acid (81.70%–97.32%), phytosterol (3466.07–6110.37 ppm), tocopherol (182.91–1276.17 mg kg⁻¹), and polyphenol (34.48–61.94 mg kg⁻¹). The factor analyses revealed that the FRO and BT hotpot oils were significantly different and were affected by the iodine value, acid value, and linoleic acid and phytosterol contents. Practical applications: It is necessary to improve the nutritional value and taste of hotpot oils to facilitate rapid development in the hotpot seasoning industry. This study showed FRO was a positive mediator of antioxidant, anti-inflammatory, and anticancer effects owing to its richness of nutritional compounds, such as polyphenols, phytosterols, and tocopherols. In comparison, BT was found to have a lower nutritional value than FRO but added a unique taste and aroma to the hotpot. The use of blended oil as raw oil could also improve the quality of hotpot oil. This information will provide an important guide to the nutritional value and industrial production of hotpot oil. Blended oil is a promising raw oil for future use in hotpot seasoning processing to meet consumer demands for nutritious and pleasantly flavored hotpot oil.