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为优化薄壳山核桃油水酶法提取工艺，以薄壳山核桃仁为原料，采用水酶法提取油脂，筛选出水酶法提油的适宜酶制剂。在单因素试验基础上，采用正交试验研究料液比、加酶量、酶解温度、酶解时间和酶解pH对薄壳山核桃油提取率的影响，并对比了水酶法、压榨法和溶剂浸提法3种方法制取的薄壳山核桃油的品质。结果表明：蛋白酶为适宜的酶制剂；水酶法提取薄壳山核桃油的最佳工艺条件为料液比1∶ 4、加酶量2.5％、酶解温度55 ℃、酶解时间2.0 h、酶解pH 8，在此条件下薄壳山核桃油提取率为68.44％；薄壳山核桃油中含有7种主要脂肪酸，分别是棕榈酸、硬脂酸、油酸、亚油酸、α-亚麻酸、花生酸和顺-11-二十碳烯酸，不饱和脂肪酸含量高达90%以上，且以油酸和亚油酸为主，油酸含量高达70%以上，亚油酸含量在15%以上。3种制油方法中，水酶法制取的薄壳山核桃油具有较高的油酸、生育酚、总酚、β-谷甾醇和角鲨烯含量，油脂品质最好。水酶法是一种较为理想的核桃油提取方法。In order to optimize the process of aqueous enzymatic extraction of pecan oil, with the pecan nut as the raw material,the oil was extracted by aqueous enzymatic method and suitable enzyme was selected. On the basis of single factor experiment, the effects of solid-liquid ratio, enzyme dosage, enzymatic hydrolysis temperature, enzymatic hydrolysis time and enzymatic hydrolysis pH on the extraction rate of pecan oil were studied by orthogonal experiment, and the qualities of pecan oils produced by aqueous enzymatic method, pressing method and solvent extraction method were compared. The results showed that protease was selected as the suitable enzyme. The optimal conditions of aqueous enzymatic extraction of pecan oil were obtained as follows: solid-liquid ratio 1∶ 4, enzyme dosage 25%, enzymatic hydrolysis temperature 55 ℃, enzymatic hydrolysis time 2.0 h, and enzymatic hydrolysis pH 8. Under these conditions, the extraction rate of pecan oil was 68.44%. There were seven main fatty acids in pecan oil including palmitic acid, stearic acid, oleic acid, linoleic acid, α-linolenic acid, arachidic acid and cis-11-eicosenoic acid. The content of unsaturated fatty acids was higher than 90%, mainly oleic acid and linoleic acid. Oleic acid and linoleic acid accounted for more than 70% and 15% respectively. Comparing the three oil producing methods, the quality of pecan oil extracted by aqueous enzymatic method was the best with higher contents of oleic acid, tocopherol, total phenols, β-phytosterol and squalene. Aqueous enzymatic method is an ideal method to extract pecan oil.

Supramolecular polymers (SMPs) have quite different crystallization behavior from the conventional polymers, because of the confinement effects of supramolecular units. Crystallization of SMPs undergoes in a "confined" and "dynamic" manner. Herein, we selected the 2-ureido-4[1H]-pyrimidione (UPy)-bonded poly(l-lactic acid) (PLLA) as a model SMP and investigated the crystallization kinetics, polymorphic crystalline structure and phase transition of supramolecular PLLAs (SM-PLLAs). SM-PLLAs were synthesized by the end functionalization of hydroxyl-terminated 2- and 3-arm PLLA precursors with different molecular weights. Crystallization rate and crystallinity of SM-PLLAs are strongly depressed in both nonisothermal and isothermal crystallizations, as compared to the nonfunctionalized PLLA precursors. Crystalline structure of SM-PLLAs is sensitive to the crystallization temperature (Tc). A low Tc (75-95 °C) facilitates the formation of metastable β crystals of PLLA in SM-PLLAs; while a high Tc (100-130 °C) favors the generation of α (or α') crystals. The β crystals formed in SM-PLLAs transform into the more stable α crystals in the following heating process. We propose that the preferential formation of β crystals is ascribed to the "strong" confinements of UPy motifs and UPy-UPy interactions, which may exert an orientation and stretching effects to the linked PLLA chains during crystallization. This study has shed light on the unique "confined" and "dynamic" crystallization behavior of SMPs and also paved a way to obtain the PLLA β-form from SM-PLLA under the crystallization conditions free of pressure, stretching, and shearing. [ABSTRACT FROM AUTHOR]

Precipitation (or solvent displacement) method has been a simple yet efficient way to prepare the micro- and nanoparticles of polymers. However, control over the particle morphology of semicrystalline polymer is extremely challenging in the precipitation method, due to the interplay of polymer crystallization with liquid-liquid phase separation in solution. This limits the preparation of polymer particles with well-controlled morphology. Herein we report on the preparation of flower-shaped and spherical biodegradable polymer particles by precipitating the ureido-4[1H]-pyrimidione-functionalized supramolecular poly(lactic acid) (PLA) from a good solvent to an antisolvent. Morphology of PLA particles was successfully manipulated by the solution crystallization, molecular weight, and intermolecular interactions of polymer precursors. Homocrystallization of supramolecular poly(l-lactic acid) yielded the flower-shaped particles in precipitation; yet stereocomplex crystallization of PLA supramolecular copolymers led to the formation of sphere particles. The underlying mechanism for crystallization-driven formation of various particles was proposed. The prepared sphere particles can be used as the carriers of hydrophobic drug. Degradation and drug release rates of the prepared PLA particles decreased with increasing the content of stereocomplexes. Our study paves a way to the biodegradable PLA particles with controllable morphologies that may find potential applications in biomedical field. [ABSTRACT FROM AUTHOR]