Candida rugosa lipase LIP1-catalyzed transesterification to produce human milk fat substitute

Structured lipids (SLs) containing palmitic and oleic acids were synthesized by transesterification of tripalmitin with either oleic acid or methyl oleate as acyl donor. This SL with palmitic acid at the sn-2 position and oleic acid at sn-1,3 positions is similar in structure to human milk fat triacylglycerol. LIP1, an isoform of Candida rugosa lipase (CRL), was used as biocatalyst. The effects of reaction temperature, substrate molar ratio, and time on incorporation of oleic acid were investigated. Reaction time and temperature were set at 6, 12, and 24 h, and 35, 45, and 55 degrees C, respectively. Substrate molar ratio was varied from 1:1 to 1:4. The highest incorporation of oleic acid (37.7%) was at 45 degrees C with methyl oleate as acyl donor. Oleic acid resulted in slightly lesser (26.3%) incorporation. Generally, higher percentage incorporation of oleic acid was observed with methyl oleate (transesterification) than with oleic acid (acidolysis). In both cases percentage incorporation increased with reaction time. Incorporation decreased with increase in temperature above 45 degrees C. Initially, oleic acid incorporation increased with increase in substrate molar ratio up to 1:3. LIP1 was also compared with Lipozyme RM IM as biocatalysts. The tested reaction parameters were selected on the basis of maximum incorporation of C18:1 obtained during optimization of LIP1 reaction conditions. Reaction temperature was maintained at 45, 55, and 65 degrees C. Lipozyme RM IM gave highest oleic acid incorporation (49.4%) at 65 degrees C with methyl oleate as acyl donor. Statistically significant (P < 0.05) differences were observed for both enzymes. SL prepared using Lipozyme RM IM may be more suitable for possible use in human milk fat substitutes.     

Synthesis of structured triacylglycerols by lipase-catalyzed acidolysis in a packed bed bioreactor

Structured triacylglycerols (ST) from canola oil were produced by enzymatic acidolysis in a packed bed bioreactor. A commercially immobilized 1,3-specific lipase, Lipozyme IM, from Rhizomucormiehei, was the biocatalyst and caprylic acid the acyl donor. Parameters such as substrate flow rate, substrate molar ratio, reaction temperature, and substrate water content were examined. High-performance liquid chromatography was used to monitor the reaction and product yields. The study showed that all of the parameters had effects on the yields of the expected di-incorporated (dicaprylic) ST products. Flow rates below 1 mL/min led to reaction equilibrium, and lower flow rates did not raise the incorporation of caprylic acid and the product yield. Incorporation of caprylic acid and the targeted di-incorporated ST was increased by approximately 20% with temperature increase from 40 to 70 degrees C. Increasing the substrate molar ratio from 1:1 to 7:1 increased the incorporation of caprylic acid and the product yield slightly. Water content in the substrate also had a mild influence on the reaction. Water content at 0.08% added to the substrate gave the lowest incorporation and product yield. The use of solvent in the medium was also studied, and results demonstrated that it did not increase the reaction rate at 55 degrees C when 33% hexane (v/v) was added. The main fatty acids at the sn-2 position of the ST were C(18:1), 54. 7 mol %; C(18:2), 30.7 mol %; and C(18:3), 11.0 mol %.     

Lipase-catalyzed acidolysis of tripalmitin with hazelnut oil fatty acids and stearic acid to produce human milk fat substitutes

Structured lipids (SLs) containing palmitic, oleic, stearic, and linoleic acids, resembling human milk fat (HMF), were synthesized by enzymatic acidolysis reactions between tripalmitin, hazelnut oil fatty acids, and stearic acid. Commercially immobilized sn-1,3-specific lipase, Lipozyme RM IM, obtained from Rhizomucor miehei was used as the biocatalyst for the enzymatic acidolysis reactions. The effects of substrate molar ratio, reaction temperature, and reaction time on the incorporation of stearic and oleic acids were investigated. The acidolysis reactions were performed by incubating 1:1.5:0.5, 1:3:0.75, 1:6:1, 1:9:1.25, and 1:12:1.5 substrate molar ratios of tripalmitin/hazelnut oil fatty acids/stearic acid in 3 mL of n-hexane at 55, 60, and 65 degrees C using 10% (total weight of substrates) of Lipozyme RM IM for 3, 6, 12, and 24 h. The fatty acid composition of reaction products was analyzed by gas-liquid chromatography (GLC). The fatty acids at the sn-2 position were identified after pancreatic lipase hydrolysis and GLC analysis. The results showed that the highest C18:1 incorporation (47.1%) and highest C18:1/C16:0 ratio were obtained at 65 degrees C and 24 h of incubation with the highest substrate molar ratio of 1:12:1.5. The highest incorporation of stearic acid was achieved at a 1:3:0.75 substrate molar ratio at 60 degrees C and 24 h. For both oleic and stearic acids, the incorporation level increased with reaction time. The SLs produced in this study have potential use in infant formulas.     

Synthesis of structured triacylglycerols containing caproic acid by lipase-catalyzed acidolysis: optimization by response surface methodology.

Production in a batch reactor with a solvent-free system of structured triacylglycerols containing short-chain fatty acids by Lipozyme RM IM-catalyzed acidolysis between rapeseed oil and caproic acid was optimized using response surface methodology (RSM). Reaction time (t(r)), substrate ratio (S(r)), enzyme load (E(l), based on substrate), water content (W(c), based on enzyme), and reaction temperature (T(e)), the five most important parameters for the reaction, were chosen for the optimization. The range of each parameter was selected as follows: t(r) = 5-17 h; E(l) = 6-14 wt %; T(e) = 45-65 degrees C; S(r) = 2-6 mol/mol; and W(c) = 2-12 wt %. The biocatalyst was Lipozyme RM IM, in which Rhizomucor miehei lipase is immobilized on a resin. The incorporation of caproic acid into rapeseed oil was the main monitoring response. In addition, the contents of mono-incorporated structured triacylglycerols and di-incorporated structured triacylglycerols were also evaluated. The optimal reaction conditions for the incorporation of caproic acid and the content of di-incorporated structured triacylglycerols were as follows: t(r) = 17 h; S(r) = 5; E(l) = 14 wt %; W(c) = 10 wt %; T(e) = 65 degrees C. At these conditions, products with 55 mol % incorporation of caproic acid and 55 mol % di-incorporated structured triacylglycerols were obtained.     

Modifications of stearidonic acid soybean oil by enzymatic acidolysis for the production of human milk fat analogues

Structured lipids (SLs) from stearidonic acid (SDA) soybean oil pre-enriched with palmitic acid (PA) at the sn-2 position with Novozym 435 (NSL) or Lipozyme TL IM (LSL) from previous research were further enriched with γ-linolenic acid (GLA) or docosahexaenoic acid (DHA). Small-scale acidolysis reactions with Lipozyme TL IM were performed to determine the optimal reaction conditions as 1:1 substrate mole ratio of NSL or LSL to free DHA at 65 °C for 24 h and a 1:0.5 substrate mole ratio of NSL or LSL to free GLA at 65 °C for 12 h. Optimized SL products were scaled up in a 1 L stir-batch reactor, and the resulting SLs of NSL:DHA (NDHA), LSL:DHA (LDHA), NSL:GLA (NGLA), and LSL:GLA (LGLA) were chemically and physically characterized. The SLs contained >54% PA at the sn-2 position with GLA >8% for the GLA SLs and DHA >10% for the DHA SLs. The oxidative stabilities of the SLs were increased by the addition of 200 ppm TBHQ, with NGLA being more stable due to higher tocopherol content than the other SLs. The melting and crystallization profiles did not differ between the DHA SLs or the GLA SLs. The triacylglycerol (TAG) species were similar for the GLA SLs but differed between the DHA SLs, with tripalmitin being the major TAG species in all SLs.     

Production of saturated acyl L-ascorbate by immobilized lipase using a continuous stirred tank reactor

6-O-decanoyl, 6-O-dodecanoyl, or 6-O-tetradecanoyl L-ascorbate was continuously produced at 50 degrees C using a continuous stirred tank reactor (CSTR) with an immobilized lipase, Chirazyme L-2 C2, from Candida antarctica. Acetone was used as the reaction medium. For each saturated acyl L-ascorbate, the productivity of ca. 60 g/L reactor/day was achieved for at least 11 days. The solubility of the saturated acyl L-ascorbate in the soybean oil or water was measured at various temperatures. The solubilities in both the soybean oil and the water were higher for L-ascorbate with a shorter acyl chain. The acyl chain dependence of the solubility in water was stronger than that of the solubility in soybean oil. The temperature dependences of the solubility in both soybean oil and water could be expressed by the van't Hoff equation, and the dissolution enthalpy (DeltaH) values for the soybean oil and water were about 20 and 90 kJ/mol, respectively, irrespective of the acyl chain length. The radical scavenging activities of L-ascorbic acid and the saturated acyl L-ascorbates against 1,1-diphenyl-2-picrylhydrazyl free radical were ca. 95% for all of the compounds, and the introduction of a saturated acyl group to the L-ascorbic acid did not affect the activity.     

Characterization of stearidonic acid soybean oil enriched with palmitic acid produced by solvent-free enzymatic interesterification

Stearidonic acid soybean oil (SDASO) is a plant source of n-3 polyunsaturated fatty acids (n-3 PUFAs). Solvent-free enzymatic interesterification was used to produce structured lipids (SLs) in a 1 L stir-batch reactor with a 1:2 substrate mole ratio of SDASO to tripalmitin, at 65 °C for 18 h. Two SLs were synthesized using immobilized lipases, Novozym 435 and Lipozyme TL IM. Free fatty acids (FFAs) were removed by short-path distillation. SLs were characterized by analyzing FFA and FA (total and positional) contents, iodine and saponification values, melting and crystallization profiles, tocopherols, and oxidative stability. The SLs contained 8.15 and 8.38% total stearidonic acid and 60.84 and 60.63% palmitic acid at the sn-2 position for Novozym 435 SL and Lipozyme TL IM SL, respectively. The SLs were less oxidatively stable than SDASO due to a decrease in tocopherol content after purification of the SLs. The saponification values of the SLs were slightly higher than that of the SDASO. The melting profiles of the SLs were similar, but crystallization profiles differed. The triacylglycerol (TAG) molecular species of the SLs were similar to each other, with tripalmitin being the major TAG. SDASO's major TAG species comprised stearidonic and oleic acids or stearidonic, α-linolenic, and γ-linolenic acids.     

Controlling molecular weight and degree of deacetylation of chitosan by response surface methodology

Response surface methodology (RSM) was used for controlling molecular weight (MW) and degree of deacetylation (DOD) of chitosan in chemical processing. In a reduced model, MW of chitosan is y = 1736166.406 - 250.745X(1)X(2) - 265.452X(2)X(3), with R( 2) = 0.86, and DOD of chitosan is y = 30.6069 + 0.3396X(1) + 0.4948X(2) + 0.0094X(3)(2), with R( 2) = 0.89. MW of chitosan depends on the crossproduct of temperature and NaOH concentration and the crossproduct of NaOH concentration and time, and DOD depends linearly on temperature and NaOH concentration, and quadratically on time. Chitosan was widely depolymerized in a range from 1,100 kDa to 100 kDa and deacetylated from 67.3 to 95.7% by NaOH alkaline treatment. MW and DOD of chitosan were drastically decreased and increased, respectively, with increase of temperature, reaction time, and NaOH concentration. Furthermore, the rate of MW decrease and DOD increase of chitosan gradually decreased with prolonged reaction time.     

Lipase-catalyzed modification of rice bran oil to incorporate capric acid

Capric acid (C10:0) was incorporated into rice bran oil with an immobilized lipase from Rhizomucor miehei as the biocatalyst. Effects of incubation time, substrate mole ratio, enzyme load, and water addition on mole percent incorporation of C10:0 were studied. Transesterification was performed in an organic solvent, hexane, and under solvent-free condition. Pancreatic lipase-catalyzed sn-2 positional analysis and tocopherol analysis were performed before and after enzymatic modification. Products were analyzed by gas-liquid chromatography (GLC) for fatty acid composition. After 24 h of incubation in hexane, there was an average of 26.5 +/- 1.8 mol % incorporation of C10:0 into rice bran oil. The solvent-free reaction produced an average of 24.5 +/- 3.7 mol % capric acid. In general, as the enzyme load, substrate mole ratio, and incubation time increased, the mole percent of capric acid incorporation also increased. Time course reaction indicated C10:0 incorporation increased up to 27.0 mol % at 72 h, for the reaction in hexane, and up to 29.6 mol % at 12 h, for the solvent-free reaction. The highest C10:0 incorporations (53.1 and 43.2 mol %) for the mole ratio experiment occurred at a mole ratio of 1:8 for solvent and solvent-free reactions, respectively. The highest C10:0 incorporation (27.9 mol %) for the reaction in hexane occurred at 10% enzyme load, and the highest incorporation (34.4 mol %) for the solvent-free reaction occurred at 20% enzyme load. Incorporation of C10:0 into rice bran oil declined with the addition of increasing amounts of water after reaching 30.3 mol % at 2% water addition in hexane, and in the solvent-free reaction after reaching 35.9 mol %.     

基于品质和能耗的杏鲍菇微波真空干燥工艺参数优化

为了提高杏鲍菇干制产品品质,降低干燥能耗,该文应用微波真空技术干燥杏鲍菇。采用三元二次回归旋转组合设计方法进行工艺参数优化试验,考察分析微波强度(X1)、物料厚度(X2)、腔体绝对压力(X3)因素对品质指标色差(Y1)、复水比(Y2)、氨基酸含量(Y3)和单位能耗(Y4)的影响及因子间交互作用对指标的影响;采用线性加权法,将多目标综合优化,确定干燥工艺的最优参数组合。结果表明:微波强度、物料厚度、腔体绝对压力对试验指标色差、复水比、氨基酸含量、单位能耗影响显著,物料厚度是影响色差的主要因素,物料厚度小于2 cm时,产品色泽较差;腔体绝对压力是影响复水比和氨基酸含量的主要因素,较小的腔体绝对压力有利于产品复水和减少氨基酸损失;微波强度是影响单位能耗的主要因素,高的微波强度,能耗较高,高的微波强度与较小的腔体绝对压力组合时,干燥能耗更高;杏鲍菇微波真空干燥高品质低能耗的最优工艺参数组合为微波强度12.5 kW/kg、物料厚度2.4 cm、腔体绝对压力18 kPa,此条件下干燥的产品品质优良,色泽洁白,色差L为78,复水性好,复水比为1.58,氨基酸破坏少,其值为473.1 mg/100 g,单位能耗较低,为9.3 kJ/kg。     

Synthesis of structured lipids containing medium-chain and omega-3 fatty acids

The ability of different lipases to incorporate omega3 fatty acids, namely, eicosapentaenoic acid (EPA, C20:5n-3), docosapentaenoic acid (DPA, C22:5n-3), and docosahexaenoic acid (DHA, C22:6n-3), into a high-laurate canola oil, known as Laurical 35, was studied. Lipases from Mucor miehei (Lipozyme-IM), Pseudomonas sp. (PS-30), and Candida rugosa (AY-30) catalyzed optimum incorporation of EPA, DPA, and DHA into Laurical 35, respectively. Other lipases used were Candida anatrctica (Novozyme-435) and Aspergillus niger (AP-12). Response surface methodology (RSM) was used to obtain a maximum incorporation of EPA, DPA, and DHA into high-laurate canola oil. The process variables studied were the amount of enzyme (2-6%), reaction temperature (35-55 degrees C), and incubation time (12-36 h). The amount of water added and mole ratio of substrates (oil to n-3 fatty acids) were kept at 2% and 1:3, respectively. The maximum incorporation of EPA (62.2%) into Laurical 35 was predicted at 4.36% of enzyme load and 43.2 degrees C over 23.9 h. Under optimum conditions (5.41% enzyme; 38.7 degrees C; 33.5 h), the incorporation of DPA into high-laurate canola oil was 50.8%. The corresponding maximum incorporation of DHA (34.1%) into Laurical 35 was obtained using 5.25% enzyme, at 43.7 degrees C, over 44.7 h. Thus, the number of double bonds and the chain length of fatty acids had a marked effect on the incorporation omega3 fatty acids into Laurical 35. EPA and DHA were mainly esterified to the sn-1,3 positions of the modified oils, whereas DPA was randomly distributed over the three positions of the triacylglycerol molecules. Meanwhile, lauric acid remained esterified mainly to the sn-1 and sn-3 positions of the modified oils. Enzymatically modified Laurical 35 with EPA, DPA, or DHA had higher conjugated diene (CD) and thiobarbituric acid reactive substance (TBARS) values than their unmodified counterpart. Thus, enzymatically modified oils were more susceptible to oxidation than their unmodified counterparts, when both CD and TBARS values were considered.     

Synthesis and characterization of canola oil-stearic acid-based trans-free structured lipids for possible margarine application

Incorporation of stearic acid into canola oil to produce trans-free structured lipid (SL) as a healthy alternative to partially hydrogenated fats for margarine formulation was investigated. Response surface methodology was used to study the effects of lipozyme RM IM from Rhizomucor miehei and Candida rugosa lipase isoform 1 (LIP1) and two acyl donors, stearic acid and ethyl stearate, on the incorporation. Lipozyme RM IM and ethyl stearate gave the best result. Gram quantities of SLs were synthesized using lipozyme RM IM, and the products were compared to SL made by chemical catalysis and fat from commercial margarines. After short-path distillation, the products were characterized by GC and RPHPLC-MS to obtain fatty acid and triacylglycerol profiles, 13C NMR spectrometry for regiospecific analysis, X-ray diffraction for crystal forms, and DSC for melting profile. Stearic acid was incorporated into canola oil, mainly at the sn-1,3 positions, for the lipase reaction, and no new trans fatty acids formed. Most SL products did not have adequate solid fat content or beta' crystal forms for tub margarine, although these may be suitable for light margarine formulation.     

高寒阴湿区陇薯6号脱毒原种肥密配套模式研究

为探讨高寒阴湿区栽培陇薯6号脱毒原种的最佳氮磷肥用量及密度,为推广和应用该品种提供理论依据。利用二次通用旋转组合试验设计,构建了氮肥(X1)、磷肥(X2)和栽培密度(X3)三因素与陇薯6号脱毒原种产量(Y)之间的回归模型:Y=38.139+2.519X1-3.662X12-1.719X22-1.719X32。对模型解析寻优的结果表明,高寒阴湿区陇薯6号脱毒原种块茎产量大于33 t/hm2的最优栽培方案为:施N 168.22～204.87 kg/hm2、P2O5 104.98～165.02 kg/hm2,密度为47 497～57 503株/hm2。     

Optimization of microwave-assisted extraction (MAP) for ginseng components by response surface methodology

Response surface methodology (RSM) was applied to predict optimum conditions for microwave-assisted extraction-a MAP technology-of saponin components from ginseng roots. A central composite design was used to monitor the effect of ethanol concentration (30-90%, X(1)) and extraction time (30-270 s, X(2)) on dependent variables, such as total extract yield (Y(1)), crude saponin content (Y(2)), and saponin ratio (Y(3)), under atmospheric pressure conditions when focused microwaves were applied at an emission frequency of 2450 MHz. In MAP under pre-established conditions, correlation coefficients (R (2)) of the models for total extract yield and crude saponin were 0.9841 (p < 0.001) and 0.9704 (p < 0.01). Optimum extraction conditions were predicted for each variable as 52.6% ethanol and 224.7 s in extract yield and as 77.3% ethanol and 295.1 s in crude saponins, respectively. Estimated maximum values at predicted optimum conditions were in good agreement with experimental values.     

混合重金属离子诱导的鲫鱼DNA损伤与基因表达

本研究结果表明 ,混合重金属离子诱导了鲫鱼鱼鳃、肝脏组织产生脂质过氧化作用 (LPO) ;鱼鳃、肝脏组织中的LPO产物丙二醛 (MDA)含量与暴露浓度呈指数效应关系 ;鱼鳃、肝脏的指数方程分别为Y =e- 2 87X + 0 6 87和Y =e- 2 19X + 0 115;LPO引发了DNA链的断裂损伤 ;3H TdR在鱼鳃、肝脏细胞DNA中大量掺入 ,并与重金属离子暴露浓度间呈双向效应 ;重金属离子的暴露极大地提高了鲫鱼肝脏DNA的总甲基化水平 ;重金属离子的毒性作用干扰了鲫鱼细胞的正常生理周期和基因的表达 ,是引发水生生物基因毒性作用的主要机制。     

Monitoring of monooctanoylphosphatidylcholine synthesis by enzymatic acidolysis between soybean phosphatidylcholine and caprylic acid by thin-layer chromatography with a flame ionization detector

Thin-layer chromatography with a flame ionization detector (TLC-FID) was used for monitoring the production of structured phospholipids (ML type: L, long-chain fatty acids; M, medium-chain fatty acids) by enzyme-catalyzed acidolysis between soybean phosphatidylcholine (PC) and caprylic acid. It was found that the structured PC fractionated into two to three distinct bands on both plate thin-layer chromatography (TLC) and Chromarod TLC. These three bands represented PC of the LL type, ML type, and MM type, respectively. The TLC-FID method was applied in the present study to examine the influence of enzyme dosage, reaction temperature, solvent amount, reaction time, and substrate ratio (caprylic acid/PC, mol/mol) on formation of ML-type PC in a batch reactor with Thermomyces lanuginosa lipase as the catalyst. The formation of ML-type PC was dependent on all parameters examined except for the substrate ratio. The ML-type PC content increased with increasing enzyme dosage, reaction temperature, solvent amount, and reaction time. The substrate ratio had no significant effect on the formation of ML-type PC within the tested range (3-15 mol/mol). The formation of MM-type PC was observed in some experiments, indicating that acyl migration is taking place during reaction since the lipase is claimed to be 1,3-specific. The TLC-FID method offers a simple and cheap technique for elucidation of product and byproduct formation during enzyme-catalyzed reactions for production of phospholipids containing mixtures of long- and medium-chain fatty acids.     

秸秆还田年限及还田量对稻田净温室效应的影响

本文研究了不同秸秆还田年限（2 年和13 年）和还田量（0、1.6 、3.2和4.8 t/hm2）对稻田CH4和N2O排放、土壤固碳速率和净温室效应的影响。结果表明：稻田CH4排放量在第2年和第13年均随秸秆还田量的增加呈线性增加，但第13年单位秸秆还田量对CH4排放的平均促进效应比第2年降低3%；各处理N2O排放量在第2年无显著差异，第13年显著促进N2O排放55% ~ 171%，且随秸秆还田量的增加呈线性增加；土壤固碳速率在第2年随秸秆还田量的增加呈线性增加，但第13年下降80% ~ 84%，且各处理间无显著差异；净温室效应随秸秆还田量的增加呈线性增加，但从第2年到第13年经历了从汇到源的过程，这说明秸秆还田量对净温室效应的影响受还田年限调控，其增加的温室效应逐步完全抵消了土壤固碳的减排效益，加剧了全球气候变暖。因此，稻田在长期秸秆还田条件下是一个重要的碳源，亟待优化秸秆还田技术，进一步固碳减排，以实现农业可持续发展。     

Characterization and esterification of hemicelluloses from rye straw

Hemicelluloses were extracted with 10% KOH/0.5% Na(2)B(4)O(7). 10H(2)O from delignified rye straw. Esterification of the hemicelluloses with various acyl chlorides was performed in a homogeneous N,N-dimethylformamide and lithium chloride system using 4-(dimethylamino)pyridine catalyst and triethylamine as a neutralizer. The degree of substitution was controlled between 0.37 and 1.65. Under an optimum condition (sample 14, molar ratio 3:1), >90% of the free hydroxyl groups in native hemicelluloses were stearoylated at 75 degrees C for 40 min. Meanwhile, the products were characterized by FT-IR and GPC techniques as well as their solubilities. The molecular mass measurements (31400-123300 g mol(-)(1)) showed only a minimal degradation of the macromolecular hemicelluloses during rapid reactions at 48-75 degrees C for 20-40 min.     

Stearidonic acid soybean oil enriched with palmitic acid at the sn-2 position by enzymatic interesterification for use as human milk fat analogues

Stearidonic acid (SDA, C18:4n-3) enriched soybean oil may be added to the diet to increase intake of omega-3 fatty acids (FAs). Human milk fat has ≥60% of palmitic acid (PA), by weight, esterified at the sn-2 position to improve absorption of fat and calcium in infants. Enzymatic interesterification of SDA soybean oil and tripalmitin produced structured lipids (SLs) enriched with PA at the sn-2 position of the triacylglycerol. Reactions were catalyzed by Novozym 435 or Lipozyme TL IM under various conditions of time, temperature, and substrate mole ratio. Response surface methodology was used to design the experiments. Model optimization conditions were predicted to be 1:2 substrate mole ratio at 50 °C for 18 h with 10% (by weight) Lipozyme TL IM resulting in 6.82 ± 1.87% total SDA and 67.19 ± 9.59% PA at sn-2; 1:2 substrate mole ratio at 50 °C for 15.6 h resulting in 8.01 ± 2.41% total SDA and 64.43 ± 13.69% PA at sn-2 with 10% (by weight) Novozym 435 as the biocatalyst. The SLs may be useful as human milk fat analogues for infant formula formulation with health benefits of the omega-3 FAs.     

微波爆玉米花制备条件的优化研究

探讨物料量、时间和调味料与微波玉米爆开率(Y₁)、膨胀率(Y₂)和感官分数(Y₃)的响应曲面关系，模型Y₁、Y₂、Y₃的失拟性检验不显著（p₁＞0.05、p₂＞0.05和p₃＞0.1），无失拟性因素存在；而模型的显著性检验达显著水平（p₁＜0.05、p₂＜0.01和p₃＜0.01），说明模型较好地拟合玉米爆开率、膨胀率和感官分数与各参试因子之间的关系，R²分别为0.8139、0.8737和0.9160。利用期望函数途径，对响应曲面模型进行模拟预测和验证，得到制备微波玉米的优化条件为物料量1.518水平、微波时间0.518水平、调味料比例1.118水平，玉米爆开率、膨胀率、感官分数同时达到最高，分别为97.5%、11.0和7.2。