Phytosterols and γ‐oryzanol in rice bran oils and distillates from physical refining process

Commercially available refined rice bran oil (RBO) contained high contents of phytosterol and γ‐oryzanol, that is, 858–1034 and 248–887 mg per 100 g oil, respectively. Although the crude rice bran oil (CRBO) had high contents of both phytochemicals (1362–1376 mg phytosterol per 100 g and 1599–1666 mg γ‐oryzanol per 100 g), physical refining process resulted in their reduction to 820–895 mg phytosterol per 100 g and 933–960 mg γ‐oryzanol per 100 g in RBO (P < 0.05). Both phytochemicals evaporated and accumulated in the deodoriser distillate (DD) to some extent during the deodorising step. Further distillation of DD using molecular distillation (MD) evaporated the free fatty acids (FFAs), resulting in the unevaporated fraction (UMD) having the acid values of 5.6–9.3 mg KOH g^?1. The UMD also contained 1585–3391 mg phytosterol per 100 g and 781–848 mg γ‐oryzanol per 100 g. Results suggest potential use of DD as the source of phytochemicals for further concentration by MD.     

Phytosterol Oxidation Products: Their Formation,Occurrence, and Biological Effects

Phytosterols or plant sterols are integral natural components of plant cell membranes that are abundant in vegetable oils, nuts, seeds, and grains; as well as added components in various functional foods. Due to their chemical structure, phytosterols are susceptible to oxidation under certain conditions giving rise to a family of compounds known as phytosterol oxidation products (POPs). The following review gives an in-depth account on the formation and occurrence of POPs in foodstuffs. The metabolism and biological effects of these oxides is also discussed in detail.     

加工过程中油脂色泽影响因素初探

为探明油脂在加工过程中色素的形成原因,采用单一组分添加实验,系统研究了工艺条件和油脂中磷脂、植物甾醇、蛋白质、淀粉等成分对油脂色泽形成的影响。实验结果表明:加工过程中温度越高,时间越长,油脂的色泽越深;磷脂、VE、植物甾醇、淀粉和蛋白质等组分均对油脂色泽有不同程度的影响,影响较大的是磷脂,其次是淀粉和蛋白质。控制油脂加工过程中的温度和时间,尽量脱除油脂中的磷脂、粕屑,对获得色泽较浅的产品有很大帮助。     

微生物降解植物甾醇侧链生产雄甾烯二酮的研究进展

甾体激素类药物是我国医药领域的重要门类,雄甾烯二酮是甾体激素类药物不可替代的中间体。微生物选择性降解植物甾醇侧链生成雄甾烯二酮,能替代复杂的多步化学合成法,并减轻目前由于薯蓣皂素为原料造成的资源紧缺,对合理利用我国的甾体植物资源,推动制药行业的发展有着重要的意义。本文结合相关的研究进展,综述了微生物选择性降解植物甾醇侧链菌种的选育与改良,水相体系中转化条件的优化及几种非水相转化系统的研究状况,并针对传统诱变育种耗时、费力、正突变率低、突变性状比较分散等缺陷,提出通过基因组改组技术实现突变性状优化重组,为构造甾醇微生物转化高产菌种提供广阔的发展空间。     

Phytosterol Enrichment of Rice Bran Oil by a Supercritical Carbon Dioxide Fractionation Technique

Supercritical carbon dioxide (SC–CO₂) fractionation technique was evaluated as an alternative process for reducing the free‐fatty‐acid (FFA) content and minimizing the phytosterol loss of rice bran oil (RBO) during the process. The effects of pressure (20.5 to 32.0 MPa) and temperature (45 to 80 °C) for isothermal operation of the column on the composition of the resultant fractions were examined. Low‐pressure and high‐temperature conditions were found to be favorable for minimizing triglycerides (TG) and phytosterol losses during the FFA removal from crude RBO. Rice bran oil fractions with < 1% FFA, about 95% TG, and 0.35% free sterol with 1.8% oryzanol content could be obtained utilizing the described SC–CO₂ fractionation technique.     

菜籽油精炼副产物利用

该文综述从菜籽油精炼副产物中提取、精制、分离磷脂、维生素E、甾醇主要方法、关键技 术及其利用价值。     

玉米胚芽油中微波辅助提取植物甾醇及其抗氧化性研究

以玉米胚芽油为原料,采用微波辅助提取植物甾醇,在单因素实验基础上,通过正交试验对提取工艺进行优化。结果表明,微波辅助提取玉米胚芽油中植物甾醇,优化条件为:微波温度50℃、微波时间2.5 min、微波功率600 W,料液比1∶13 g/mL,此时植物甾醇提取率可达到8.305 mg/g。以正交优化工艺条件下提取的粗甾醇为原料,研究清除羟自由基(·OH)的能力来确定它的抗氧化活性。实验结果表明,玉米胚芽油中粗甾醇具有较强的抗氧化活性。     

煎炸米糠油营养成分及煎炸油条品质分析

利用米糠油连续煎炸油条32 h,通过对煎炸米糠油中谷维素、维生素E、植物甾醇含量,以及煎炸油条含油率、酸值、过氧化值、羰基值检测和感官指标评价,分析研究米糠油在煎炸过程中营养成分的变化及煎炸油条的品质。结果表明:经过32 h的连续煎炸,煎炸油条中米糠油的酸值(KOH)从0.73 mg/g逐渐增加至1.32 mg/g,过氧化值呈现波动增长的变化趋势(由0.05 g/100 g增大至0.08 g/100 g),羰基值从12.50 meq/kg逐渐增加至61.72 meq/kg;煎炸米糠油中谷维素含量相对稳定,植物甾醇含量有所降低(从1.67%降低至1.23%),维生素E含量从57.04 mg/100 g显著降低至1.18 mg/100 g;煎炸油条的平均含油率为12.38%;煎炸油条的含油率低、感官效果好。     

超声波法提取米糠中植物甾醇的工艺研究

植物甾醇是植物中广泛存在的一类具有重要生物活性的物质。采用超声波法从米糠中提取植物甾醇，以植物甾醇得率为指标。通过单因素实验和正交实验确定其优化工艺条件为：提取溶剂乙酸乙酯，料液比（w/v）1：15，提取温度70℃，提取时间90min，超声波功率160W。与热回流法比较，超声波法提取极大的缩短提取时间，而且提取得率略有提高。