Enzymatic and Chemical Interesterification of Rice Bran Oil,Sheaolein, and Palm Stearin and Comparative Study of Their Physicochemical Properties

Abstract: Total of 3 different mixtures of rice bran oil (RBO), sheaolein (SO), and palm stearin (PS) (RBO : SO : PS, 40 : 35 : 25; 15 : 40 : 45; 10 : 35 : 55) were modified by enzymatic interesterification (EIE) using TLIM as a bio‐catalyst. After interesterification, a physicochemical properties of selected ratio (10 : 35 : 55; RBO : SO : PS) was compared with chemical interesterification (CIE). CIE sample showed higher SFC than EIE in each measured temperature. DAG content was lower in CIE than EIE sample. Besides, each EIE or CIE products were compared with blends, where higher SFC, longer induction time was observed in the blends. Oxidative stability was measured based on Rancimat and peroxide value (PV) where EIE sample showed longer induction time and lower PV compared to CIE sample. Further, EIE sample was selected for oxidation studies and kept at 60 °C for 22 d after the addition of antioxidants (EGCG, rosemary) where induction time was significantly increased compared to control. EGCG containing sample showed longer induction time and lower PV compared to rosemary containing sample. Practical Application: This research can show the application of SO in the bakery industry, which is a byproduct of shea butter production. There is very limited published information about SO application in bakery food. In addition, it could be useful for industrial application to compare the physicochemical properties of enzymatic interesterification compared to chemical interesterification.     

油脂分提工艺研究进展与应用

该文介绍油脂分提结晶技术原理,并对油脂分提结晶技术设备及其应用进行初步介绍,为国内油脂改性技术应用提供依据。     

棕榈油硬脂和大豆油酶法酯交换的研究

进行了固定化脂肪酶Lipozyme TL IM催化棕榈油硬脂和大豆油酶法酯交换的研究,考察了酶法酯交换分批操作的反应动力学曲线,发现5%的加酶量、70℃下反应,反应3 h内达到平衡,反应温度在70~90℃对反应速度无明显影响。采用填充床式反应器进行连续反应,结果表明通过装有10 g脂肪酶柱子的最佳流速为30 g/h。对化学酯交换和酶法酯交换产品性质的比较发现,二者SFC无明显差异。采用填充床式反应器对40∶60和30∶70的棕榈油硬脂和大豆油的混合物进行酶法酯交换反应,测定了反应产物的SFC曲线,为将来的应用开发提供参考数据。     

无溶剂系统脂肪酶促POMF酯交换生产CBE的动力学研究

研究了无溶剂系统脂肪酶促棕榈油中间熔点物酯交换生产类可可脂的动力学，在优化的反应条件下，建立了初始底物浓度对反应初速度的影响和三种主要甘三酯浓度随时间变化的两个动力学模型。实验结果表明，计算值与实验值较吻合。     

大豆油调和不同熔点棕榈液油的冷藏试验

为了制备适应不同储存温度的豆油-棕榈液油调和油,以大豆油与不同熔点棕榈液油为原料,采用冷藏试验方法优化抑晶剂种类、用量和调和油配方。结果表明,羟基硬脂精是效果最佳的抑晶剂,其最佳添加量为0.025%;调和油1(豆油70%+10℃棕榈油30% +羟基硬脂精0.025%)在0℃环境下储存可保持16h以上澄清透亮,在5℃条件可保持72h以上澄清透亮;调和油2(豆油70%+18℃棕榈油30%+羟基硬脂精0.025%)在10℃环境下可保持30h以上澄清透亮;调和油3(豆油60%+18℃棕榈油40%+羟基硬脂精0.025%)在15℃环境下可保持20h以上澄清透亮;调和油4(豆油60%+24℃棕榈油40%+羟基硬脂精0.025%)在20℃环境下可保持10h以上澄清透亮。     

油脂干法分提及其应用

介绍了油脂干法分提的原理和意义，着重介绍分提设备以及干法分提在棕榈油、牛脂、无水乳脂、禽脂、鱼油中的应用。     

无溶剂系统酶促POMF连续化酯交换反应生产类可可脂研究

通过填充床酶反应器中POMF与SME酯交换生产类可可脂(CBE)连续化反应实验,研究空速对产率(R)和连续化特异性酯交换能力(CSIV)影响。当SI为0.54时,R值为121％,比产量(PE)为3.99 g·g～1·h-1。经过差示扫描量热法(DSC)分析,产品热性能符合类可可脂质量要求。     

果糖-赖氨酸模型体系美拉德产物不同级分对抑制香蕉酶促褐变相关性质的影响

非硫无毒的抗褐变抑制剂的筛选是目前的研究热点。前期研究显示果糖-赖氨酸模型体系美拉德反应产物对香蕉酶促褐变具有明显的抑制效果。本文研究了分级对该体系产物抑制香蕉酶促褐变相关性质的影响。首先通过超滤、透析等方法将美拉德产物分级为MW<3500 u、MW>5000 u及3500 u5000 u级分的螯合铜离子能力最好,MW<3500 u级分次之。MW<3500 u级分的DPPH?清除能力和抑制香蕉多酚氧化酶能力更佳,分别达46.13%、0.089 mg/mL（IC50）。三种级分对游离酶和酶-底物络合物的抑制常数分别为：KI=0.297 mmol/L,KIS=1.744 mmol/L（MW>5000 u）;KI=0.212 mmol/L,KIS=1.656 mmol/L（3500~5000 u）;KI=0.205 mmol/L,KIS=1.536 mmol/L（MW<3500 u）。说明MW<3500 u级分与游离酶及酶-底物络合物结合更紧密。综上,MW<3500 u的MRPs具有最优的抑制香蕉酶促褐变的能力。     

分提棕榈油性质及其等温结晶过程研究

对比分析熔点为44℃(A)、24℃(B)两种分提棕榈油甘三酯组成、固脂含量、等温结晶特性及等温结晶动力学规律。结果表明：甘三酯的组成对于两者的结晶性能具有很大影响。在等温结晶过程中,样品A能够较快速达到结晶终点。在各等温条件下,A的Avrami指数n与B相差不大,说明两者基于过冷状态下的结晶机理相同。     

油脂分提工艺的进展与应用

油脂分提结晶技术始于20世纪初,分提工艺经近百年的发展,特别是20世纪70年代中叶棕榈油产量的迅猛增加有力地推动了分提技术设备的进步,尤其隔膜压滤机在干法分提中的应用.目前干法分提工艺已被广泛地应用于多种油脂的分提,并能生产出顶级油酸甘油酯、超级硬脂、食品专用油脂在内的多种油脂产品.     

乳脂肪干法分提组分化学组成及热力学特性

在10～40 ℃范围内,通过逐级升温方式,将无水乳脂肪干法分提成低熔点L20、中熔点L30和L40、高熔点S40四组分,并通过气相色谱-质谱联用法对各组分中脂肪酸（fatty acid,FA）、甘油三酯（triglyceride,TAG）种类及含量进行测定。结果表明：随着分提温度升高,L20～S40,饱和脂肪酸（saturated fatty acid,SFA）含量呈递增而不饱和脂肪酸（unsaturated fatty acid,USFA）呈递减趋势,S40富含长链SFA,短链SFA及USFA较少,而L20与之正好相反,L30和L40 FA组成则介于L20～S40之间;热图分析显示：高熔点TAG较多存在于S40中,低熔点TAG主要存在于L20中,L30和L40则富含中熔点TAG;通过差示扫描量热仪分析,发现乳脂肪及各分提组分结晶-熔化曲线存在显著差异,结晶温度和熔化温度由高到低依次为S40＞L40＞L30＞L20（P＜0.05）,结晶/熔化温度高,液态油与固态脂发生相转变时所需要的相变潜热就大,这为搅打稀奶油原料选择,搅打温度、时间和贮存温度等工艺配方参数设计提供理论依据;通过X射线晶体衍射分析,在长间距衍射中,高熔点组分S40、L40显示结晶状态均为以β’晶型为主的α、β’、β多晶型混晶,而L20和L30中无晶型衍射峰,说明低熔点组分为无定型状态的油脂;在短间距衍射中显示乳脂肪、S40、L40晶体以二倍链长（2L）（40.76、13.49 ?）和三倍链长（3L）（29.44 ?）方式堆积,而L20和L30仅以2L方式堆积。综上所述,脂肪饱和程度高则晶体稳定性强,结晶-熔化所产生的热焓大,适合制备硬脂产品,反之,则适合制备软脂或对硬度要求不高的产品。通过对不同熔点乳脂肪理化性质的系统研究,为实际生产中乳脂肪类型的不同需求选择提供参考数据。     

猪油与棕榈硬脂酶法酯交换制备零反式脂肪酸起酥油的研究

研究了固定化脂肪酶Lipozyme RM IM催化猪油和棕榈硬脂酯交换制备起酥油的工艺,考察了反应温度、酶添加量、反应时间对酯交换反应的影响.并以反应后体系在20℃下的固体脂肪含量(SFC)为指标,确定了理想的工艺条件:反应温度60℃,酶添加量8％,反应时间1h.利用等温曲线和X-射线衍射技术研究了混合体系酯交换前后的相容性和晶体形态,结果表明:经酯交换后,混合体系的相容性得到显著改善,晶型由β型转变为β’型,适宜用作焙烤起酥油.     

Generation,Fractionation, and Characterization of Iron‐Chelating Protein Hydrolysate from Palm Kernel Cake Proteins

Palm kernel cake protein was hydrolyzed with different proteases namely papain, bromelain, subtilisin, flavourzyme, trypsin, chymotrypsin, and pepsin to generate different protein hydrolysates. Peptide content and iron‐chelating activity of each hydrolysate were evaluated using O‐phthaldialdehyde‐based spectrophotometric method and ferrozine‐based colorimetric assay, respectively. The results revealed a positive correlation between peptide contents and iron‐chelating activities of the protein hydrolysates. Protein hydrolysate generated by papain exhibited the highest peptide content of 10.5 mM and highest iron‐chelating activity of 64.8% compared with the other hydrolysates. Profiling of the papain‐generated hydrolysate by reverse phase high performance liquid chromatography fractionation indicated a direct association between peptide content and iron‐chelating activity in most of the fractions. Further fractionation using isoelectric focusing also revealed that protein hydrolysate with basic and neutral isoelectric point (pI) had the highest iron‐chelating activity, although a few fractions in the acidic range also exhibited good metal chelating potential. After identification and synthesis of papain‐generated peptides, GGIF and YLLLK showed among the highest iron‐chelating activities of 56% and 53%, whereas their IC₅₀ were 1.4 and 0.2 μM, respectively.     

Mutagenicity of Edible Palm Oil on the Ghanaian Market before and after Repeated Heating

Red palm oil produced in Ghana largely by village folks has never been tested for its mutagenic potential. The study aimed at determining the mutagenicity of high‐energy heated red palm oil (RRPO) and refined, bleached imported palm oil (PO) on the Ghanaian market. Samples of RRPO and PO were 1× and 5× heated for 10 min at 180 °C with a cooling period of 5 h in‐between. Unheated, together with heated samples, were tested for mutagenicity using Salmonella typhimurium TA 98 and TA 100 tester stains. Unheated PO was negative for the Ames mutagenicity test with TA 98 strain. However, 1× and 5× heated PO were mutagenic (P = 0.05, each). Testing PO, using TA 100 strain was negative. RRPO was mutagenic with TA 98 strain for heated oils (P = 0.05, each). Assays with TA 100 strain showed highly significant mutations (P = 0.001, each) that increased with increasing heating frequency. PO 1× and 5× heated samples caused significant frameshift mutation in the S. typhimurium TA 98 strain. RRPO caused highly significant point and frameshift mutations in heated samples. Furthermore, unheated RRPO mutagenic potential has serious health implications.     

Characterization and Treatments of Oil Palm Frond Fibers and Its Suitability for Technical Applications

The aim of this paper is to explore the potential of oil palm frond fibers (OPFf) for technical applications such as composite reinforcement. For this purpose, fibers obtained from frond wastes were subjected to various chemical treatments with NaOH and chemically and morphologically characterized. Afterward, composites of poly-lactic acid matrix and nonwoven matts made with the treated and the untreated OPFf were prepared and the mechanical properties tested. It was found that the alkaline treatment was effective for increasing the wettability of the fibers leading to composites with a good-balanced between lightness and toughness for potential applications in packaging or automotive industries.     

胡芦巴半乳甘露聚糖的酶法改性及其产物表征

分别利用纤维素酶、普鲁兰酶及二者联用降解法对胡芦巴半乳甘露聚糖进行改性,并以原胡芦巴半乳甘露聚糖作对照,采用红外光谱(FTIR)、X- 射线衍射(XRD)、扫描电子显微镜(SEM)、热重法(TG)和差热分析法(DTA)对改性产物分子结构、结晶性能、形貌及热稳定性进行了表征。实验结果表明,不同酶解方法所得半乳甘露聚糖的黏均分子量分别为1.16 × 105、2.19 × 105、5.10 × 104,还原糖得率分别为5.1%、39.5%、43.8%。红外光谱分析表明,随着产物分子量的降低,糖类-OH 特征吸收峰及C-H 的变角振动吸收峰的强度逐渐增强,指纹区吡喃环特征吸收峰的强度逐渐减弱,但峰位置基本不变;XRD 分析表明,酶解作用对胡芦巴半乳甘露聚糖的结晶区的结构有一定的破坏作用,结晶度降低; SEM 分析表明,酶解作用对产物表面形貌影响显著,且对半乳甘露聚糖整体性严重破坏,颗粒粒度减小,表面孔隙减少;热分析图谱结果表明,随着产物分子量的降低,TG 曲线初始失重温度逐渐提高,总失重率降低,热稳定性提高;DTA 曲线放热峰顶温度逐渐降低,且峰强减弱。     

低温连续相变制备酱油渣膳食纤维及其特性研究

酱油渣是营养价值丰富但又未能合理利用的工业副产物,从中回收膳食纤维具有废物利用和环境保护的意义。本文利用自主研发的低温连续相变萃取技术制备酱油渣不溶性膳食纤维(IDF),在前期单因素试验基础上,以IDF得率为指标,对技术参数进行响应面优化,然后辅以水洗、酶解工艺对IDF进行纯化。同时,本文研究了酱油渣IDF的功能特性,并通过电镜初步阐释其微观形貌与功能特性的机理关系。结果表明,最佳技术条件为萃取压力0.5 MPa、萃取温度45℃、萃取时间67 min、原料颗粒度50目,制备得到油脂含量1%的粗IDF。再辅以纯化工艺,酱油渣IDF的纯度达70.9±0.28%。功能测试表明,酱渣IDF具有优良的膳食纤维特性,其持水力、膨胀力和吸油力分别为6.65±0.07 g/g、5.83±0.11 mL/g和2.23±0.03 g/g。与市售大豆IDF产品相比,其吸油力尤为显著。扫描电镜表明,酱油渣IDF良好功能特性与该技术下其形成的网状疏松纤维骨架结构有关。     

Comparison of Size Characterization of Barley Starch Granules Determined by Electron and Optical Microscopy,Low Angle Laser Light Scattering and Gravitational Field-Flow Fractionation

Several methods were used for the characterization of starch granules isolated from barley kernels. A procedure based on a combination of alkaline digestion, toluene treatment and filtration over sieves with pore diameters of 70 and 40 μm was used for isolation and purification of starch granules from kernels. The released starch granules were characterized by various methods: scanning electron microscopy (SEM), image analysis of optical microscopy data (IAOM), low angle laser light scattering (LALLS), and gravitational field-flow fractionation (GFFF). All methods showed the bimodal size distribution of the isolated starch granules, however, they differed in the ratio of large and small starch granules. LALLS and GFFF were also used for determination of the ratio of large and small starch granules (ratio A/B) isolated from two malting barley cultivars Kompakt and Akcent. Both techniques determined the higher ratio A/B for the cultivar Akcent. SEM was also used to examine the extent of digestion. The micrographs indicate that a significant proportion mainly of small granules are still embedded into residues of endosperm and a more extensive digestion must be performed to release all starch granules from barley kernels.