南瓜籽制油工艺研究进展

将南瓜籽制油工艺分为压榨法、萃取法、水酶法三大类,并依据此分类对当前南瓜籽制油工艺及各工艺优、劣势进行综合论述。同时,对南瓜籽制油工艺在未来的研究方向进行了展望,以期为获得高品质南瓜籽油及推进南瓜籽油产业成熟化提供支持。     

响应面优化水酶法提取裂壶藻油的工艺

以裂壶藻干藻粉为原料,以清油得率为评价指标,采用两步酶解法提取油脂。在单因素实验的基础上,对清油得率影响较大的碱性蛋白酶的作用条件应用响应面法进行优化,依据回归分析确定碱性蛋白酶的最适作用条件。结果表明,水酶法提取裂壶藻油的最适工艺条件为:料液比1∶7,中性蛋白酶添加量7%,酶解温度45℃,酶解时间3 h,酶解p H 6.5;碱性蛋白酶添加量10%,酶解温度68℃,酶解时间6 h,酶解p H 9.4。在最适工艺条件下,裂壶藻清油得率可以达到(91.37±0.14)%。气相色谱-质谱分析裂壶藻油中不饱和脂肪酸含量为47.43%,其中DHA含量为35.09%。     

预处理过程产生的抑制剂对纤维素酶酶解效率的影响

在木质纤维产乙醇研究中,原料在稀磷酸浸渍+蒸汽爆破预处理过程中容易产生糠醛、5-羟甲基糠醛、对苯二酚和间苯二酚等抑制剂,这些抑制剂会影响纤维素酶酶解效率,导致还原糖浓度下降从而影响乙醇生产。通过单因素实验和正交实验,确定了纤维素酶酶解的最优条件为:酶解温度50℃、酶液载入量30 U/mL、酶解固液比1∶11、酶解pH值4. 8;选取预处理过程中产生的上述4种抑制剂,测定其浓度分别为:糠醛0. 031 g/L、5-羟甲基糠醛0. 029 g/L、对苯二酚1. 51 g/L、间苯二酚1. 242 g/L,探讨上述抑制剂单独或复配后对纤维素酶酶解效率的影响。结果表明,预处理过程中产生的酚类抑制剂高于醛类,在酶解过程中酚类抑制剂对酶解产生的影响高于醛类抑制剂;多种抑制剂的协同作用对酶解的影响高于单一种类抑制剂对酶解的影响;酶解液中抑制剂对酶解的影响强度按对苯二酚、间苯二酚、5-羟甲基糠醛、糠醛依次减弱。     

The alginate fermentation strain Pantoea sp. F16-PCAi-T3P21 and ethanol production

Bio-ethanol production from algae is a promising way to help solve the energy problem. Alginate is a major component of algae, but it cannot be utilized by existing ethanol fermentation microorganisms. In order to improve the utilization rate of brown algae, high alginate fermentation strains should be obtained. In this research, strains for algae fermentation were got from several experiments. The ethanol yield of strain A was the highest, which was 0.095 g/g (ethanol to alginate). The identification of strain A was carried out and it was 99% identical to Pantoea sp. F16-PCAi-T3P21. Fermentation experiments with different substrates were carried out, such as laminaran, mannitol, L. japonica and acid hydrolysate of L. japonica, and the ethanol yield rate of L. japonica acid hydrolysate was the highest, which reached 0.17 g/g ethanol to L. japonica. It showed that strain A can converse alginate to ethanol in a relatively high yield rate, and might be a promising strain with L. japonica as the substrate, we believe more research should be carried out on this strain.     

碳酸钠碱性介质氧脱木素促进火炬松酶解糖化的研究

分别采用硫酸盐法（KP）和绿液法（GL）蒸煮火炬松，并以碳酸钠为碱性介质进行氧脱木素，所得浆料分别标记为KP-OC浆和GL-OC浆，分析了这两种浆料的化学组分，并对这两种浆料进行酶解以提取可发酵单糖。结果显示，在120℃氧脱木素4 h所得的KP-OC浆和GL-OC浆的木素脱出率均明显优于相近条件下以氢氧化钠为碱性介质且脱木素1 h的浆料。对于GL-OC浆和KP-OC浆，当酶用量为10 FPU/g时，酶解单糖得率、总单糖提取率最高分别可达73.2%和95.8%、72.4%和75.7%，均优于相近条件下以氢氧化钠为碱性介质氧脱木素的浆料。     

Controlled enzymatic hydrolysis on characteristic and antioxidant properties of soybean protein isolate-maltodextrin conjugates

This study aimed to investigate the effect of limited hydrolysis on conformational and antioxidant properties of soy protein isolate-maltodextrin (SPI-Md) conjugates. Extrinsic fluorescence analysis showed unfolding of the protein molecule and exposure of hydrophobic groups in SPI-Md conjugate hydrolysates. Free amino acid analysis showed that, the contents of hydrophobic amino acids in SPI-Md conjugates increased after hydrolysis. The contents of leucine, isoleucine, phenylalanine increased from 0.32, 0.30 and 0.54 to 1.36, 1.86 and 2.60, respectively, when the hydrolysis degree (DH) gradually increased from 0% to 5.7%. The FT-IR spectrum showed that C = O absorption of the amide group formed by glycosylation continued unabated after limited hydrolysis (DH 2.9%). The glycated SPI products showed good reducing power and superior resistance to lipid oxidation (34%, 12 mg mL^?1), whereas the limit hydrolysates (DH 2.9%) of SPI-Md conjugates showed more ef?cient radical-scavenging capacity (89.5%, at 12 mg mL^?1) and iron-chelation activity (91.3%, at 12 mg mL^?1). Results of this study indicated that, slight enzymatic hydrolysis (DH 0–2.9%) could help partially unfolding the globular structure of SPI-Md conjugates without deteriorating amide bonds and had a positive effect on their antioxidant properties.     

绿豆抗氧化肽的酶法制备及其抗氧化活性

为提高绿豆淀粉生产过程中产生的废弃物绿豆蛋白的资源利用率，研究了酶法制备绿豆抗氧化肽的最佳条件，并探究其抗氧化活性。通过选用不同蛋白酶及其复合酶，对绿豆蛋白进行水解，综合考虑反应时间、加酶量等因素，对酶解反应进行优化。通过体外抗氧化实验对水解制得的多肽溶液进行抗氧化能力检测，最终确立了最佳的反应条件，具体如下：选用中性蛋白酶进行酶解，底物质量分数3%，酶解时间3 h，加酶量质量分数2%，pH 7，温度50 ℃。按照该条件所制得的绿豆多肽溶液，质量浓度为5 mg/mL时，DPPH自由基清除率可达（91.58±2.44）%，同时还具有较强的还原能力。经凝胶层析柱分离纯化后得到5个分离组分，其中小分子肽段组分5的抗氧化能力最强，高于其他大分子肽段以及未分离多肽。     

芝麻粕蛋白酶法提取工艺优化及组分分析

为了综合利用芝麻粕资源，以芝麻粕为原料，利用硬脂酸、吐温80、十二烷基硫酸钠三种表面活性剂对其进行脱脂处理，再采用水剂法去除表面活性剂，最后利用中性蛋白酶、碱性蛋白酶和木瓜蛋白酶对芝麻粕蛋白进行水解，以芝麻粕蛋白溶出率为考察指标优选出最佳水解酶。在此基础上，通过单因素试验和正交试验对酶解工艺条件进行优化，并利用2,4-二硝基氟苯柱前衍生高效液相色谱法分析水解物成分。结果表明，吐温80脱脂效果最好，芝麻粕脱脂率达93.49%；碱性蛋白酶为最佳水解酶，其最佳酶解条件为料水比1∶10（g∶mL）、酶解温度50 ℃、加酶量0.04%、酶解时间3.0 h。在此最佳酶解条件下，芝麻粕蛋白溶出率为88.94%。水解物中含有20种氨基酸，其中8种人体必需氨基酸含量高于FAO/WHO的推荐值。