Potential of in-field and low temperature drying for reducing chlorophyll contents in canola (Brassica napus L)

The presence of green seeds in canola arises primarily from the common practice of swathing the crop prematurely in order to hasten the harvesting process and reduce the shattering losses. The purpose of this study was to determine the effects of plant maturity, swathing and duration of swathing on moisture and chlorophyll contents of canola seeds (Brassica napus L cv Westar), and to determine the effect of canola conditioning with air at 25·C and 90% RH on chlorophyll content. A standing crop of canola with 50% to 10% (w/w) seed moisture content was sampled at regular intervals in two consecutive harvest years (1989 and 1990). Canola was also swathed at three different stages of maturity, and seeds were checked for chlorophyll at 2-3 day intervals and compared with chlorophyll contents of seed from standing crop. Samples were conditioned in a thin layer with air at 25·C and 90% RH for 24 h, and chlorophyll was determined before and after conditioning. The chlorophyll of seeds decreased exponentially with a decrease in moisture content. Conditioning canola seeds decreased chlorophyll content by an average of 16% (SD = ± 12%).     

Evaluation of oxidative stability of canola oils by headspace analysis

Lipid oxidation is a major factor affecting flavor quality and shelf life of vegetable oils. Oxidative stability is therefore an important criterion by which oils are judged for usefulness in various food applications. In this study a method based on headspace analysis was developed to evaluate relative oxidative stability of canola oils. The method does not require the use of chemicals, involves minimal sample preparation, and can be performed on a relatively small sample size in comparison with traditional wet chemical methods. Canola oils freshly extracted in the laboratory from different seed samples were subjected to accelerated oxidation and analyzed for PV by standard methods and headspace volatiles by solid phase microextraction/GC-MS. Forward stepwise regression analysis of the data revealed a relationship between PV and headspace concentration of the volatile lipid oxidation products hexanal and trans,trans-2,4-heptadienal. The PV calculated using this formula correlated (R ²=0.73) with those measured by conventional methods. Presented in part at the 96th Annual Meeting of the AOCS, 1–4 May 2005, Salt Lake City, UT.     

Radical scavenging activity of canola hull phenolics

Possible use of canola hulls as a source of natural anti-oxidants was explored. Cyclone canola hulls were extracted with methanol (30 to 80%, vol/vol) and acetone (30 to 80%, vol/vol). The free radical-scavenging activity of phenolic extracts so prepared was evaluated using the 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical ion (ABTS^o−), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, and chemiluminescence assays. The total content of phenolics in prepared extracts from canola hulls ranged from 15 to 136 mg sinapic acid equivalents per gram of extract. Higher levels of condensed tannins were detected in the acetone extracts than in the corresponding methanolic counterparts. Seventy and 80% (vol/vol) acetone extracts displayed markedly stronger antioxidant activity than any of the other extracts investigated. Statistically significant linear correlations were found between TEAC (Trolox equivalent antioxidant capacity) values (expressed in mM of Trolox equivalents per gram of extract) and total pehnolics, TEAC and total condensed tannins (i.e., determined using the modified vanillin and pronthocyanidin assays), as well as TEAC and protein precipitation activity of phenolic extracts (i.e., measured using the dye-labeled assay). The antioxidant activities of extracts as determined by the ABTS^o− radical ion assay correlated highly with those of the chemiluminescence and DPPH radical assays.     

Efficacy of tertiary butylhydroquinone on the storage and heat stability of liquid canola shortening

The sensory (odor and flavor) and physicochemical characteristics of tertiary butylhydroquinone (TBHQ) treated and butylated hydroxyanisole/toluene (BHA/BHT) treated liquid canola shortenings, subjected to accelerated storage (Schaal oven test at 65°C) and deep fat heating (at 185°C), were determined. Data for the Schaal oven test indicate that TBHQ was effective in retarding oxidative rancidity in liquid canola shortenings. However, addition of the commonly used mixture of BHA/BHT to canola shortenings resulted in only a slight decrease in oxidation during schaal oven storage. The results obtained from deep fat heating of canola liquid shortening show that neither TBHQ nor BHA/BHT was effective in enhancing oxidative and thermal stability of this product.     

Catalytic Vicinal Diacylation of Epoxidized Triglycerides in Canola Oil

The epoxy ring opening and vicinal diacylation of fatty acids in vegetable oils was found to be promising reaction to synthesize stable biolubricants and bioplasticizers. The current research investigation is emphasized on the synthesis of a value added product vicinally diacylated canola oil by sulfated‐ZrO₂. The two‐step research approach employed includes: (i) epoxidation, and (ii) epoxy ring opening and vicinal diacylation of epoxidized triglycerides in the canola oil. Sulfated‐ZrO₂ was prepared and characterized to measure the physico‐chemical properties required for the effective catalysis. The Taguchi (L16 orthogonal array) statistical design method was employed to optimize the process conditions for the maximum formation of diacylated canola oil. Sulfated‐ZrO₂ demonstrated promising activity for the epoxy ring opening and vicinal diacylation of canola oil, and 99 % conversion was achieved at the optimum process conditions of temperature 130 °C, epoxy to acetic anhydride molar ratio (1:1.25), 16 wt% of catalyst loading and reaction time of 1 h which were inferred from the Taguchi analyses. The products were characterized and confirmed with FT‐IR, ¹H NMR and sodium spray mass spectroscopy. Spectroscopic analysis also confirmed the absence of intermediate products. The statistical analyses was undertaken to determine the order, rank and interactions among the process variables. The reaction followed Langmuir–Hinshelwood–Hougen–Watson type mechanism and the kinetic data was fitted in overall second order equation. Calculated apparent activation energy was 23.1 kcal/mol.     

Lipase-catalysed interesterification between canola oil and fully hydrogenated canola oil in contact with supercritical carbon dioxide

The processing parameters in enzymatic reactions using CO₂-expanded (CX) lipids have strong effects on the physical properties of liquid phase, degree of interesterification, and physicochemical properties of the final reaction products. CX-canola oil and fully hydrogenated canola oil (FHCO) were interesterified using Lipozyme TL IM in a high pressure stirred batch reactor. The effects of immobilised enzyme load, pressure, substrate ratio and reaction time on the formation of mixed triacylglycerols (TG) from trisaturated and triunsaturated TG were investigated. The optimal immobilised enzyme load, pressure, substrate ratio and time for the degree of interesterification to reach the highest equilibrium state were 6% (w/v) of initial substrates, 10 MPa, blend with 30% (w/w) of FHCO and 2 h, respectively. The physicochemical properties of the initial blend and interesterified products with different FHCO ratios obtained at optimal reaction conditions were determined in terms of TG composition, thermal behaviour and solid fat content (SFC). The amounts of saturated and triunsaturated TG decreased while the amounts of mixed TG increased as a result of interesterification. Thus, the interesterified product had a lower melting point, and broader melting and plasticity ranges compared to the initial blends. These findings are important for better understanding of CX-lipid reactions and for optimal formulation of base-stocks of margarine and confectionary fats to meet industry demands.     

利用多重PCR方法检测7种转基因卡诺拉油菜籽品种(系)研究

为对商业化进口7种转基因卡诺拉油菜籽品种(系)进行高通量、快速、准确检测,建立可用于鉴定7种转基因卡诺拉油菜籽品种(系)多重PCR检测方法。首先建立7种转基因油菜籽品种(系)稳定单重PCR检测体系,在此基础上再建立和优化7种转基因油菜籽品种(系)多重PCR检测体系;获得4组可用于鉴定7种转基因卡诺拉油菜籽品种(系)多重PCR检测体系,其中1组为四重PCR检测体系,3组为两重PCR检测体系。优化多重PCR体系具有较高稳定性和重复性,可作为检测该7种转基因油菜籽品种(系)有效方法。     

Volatile aldehyde emissions from heated cooking oils

Low molecular weight aldehydes (LMWAs) formed during the heating of frying media (triglycerides) were adsorbed onto tenax and analyzed by GC‐MS after thermal desorption. Six alkanals (C₅ to C₁₀), seven 2‐alkenals (C₅ to C₁₁) and 3 alkadienals (C₇, C₉ and C₁₀) were found in the fumes of canola oil (control), extra virgin olive oil, and refined olive oil, heated at 180 and 240 °C. The emission rates of these aldehydes depended on the heating temperature. Frying in any type of olive oil, independently of its commercial category, will effectively decrease the emission of volatile aldehydes at temperatures below the smoking point. Thus, using the cheaper olive oil for deep‐frying purposes will not affect aldehyde emissions. This is important since olive oil is usually used for deep‐frying operations while extra virgin olive oil is used as salad dressing in Spain. The mixture of refined olive oil with some virgin olive oil is the most acceptable type of olive oil in non‐Mediterranean countries due to its milder flavor. However, if higher temperatures are needed the use of canola oil is more advisable due to its higher smoke point. Copyright © 2004 Society of Chemical Industry     

Modification of Crude Canola Lecithin for Food Use

Crude canola lecithin was fractionated by removal of neutral lipids with acetone followed by ethanol extraction with or without supercritical carbon dioxide (SC-CO₂). Two extraction steus of 60 min each at 35°C with 500 mL acetone were optimum for maximum yield of acetone solubles and maximum phospholipid (PL) concentration (66.7%) in the acetone insoluble (AI) fraction. AI were separated into 26.5% ethanol soluble and 68.7% ethanol insoluble fractions. PL concentration in the extract increased with increasing amounts of ethanol used. Yields were low for SC-CO₂/ethanol extraction, of which extracts from 55.2 MPa/ 70°C contained 32% PL (83% phosphatidyl choline).     

小烛树蜡油脂凝胶的性质及作用机理研究

本文主要以小烛树蜡为凝胶剂,制备低芥酸菜籽油油脂凝胶。研究小烛树蜡添加量对油凝胶的相变、持油性、固体脂肪含量（solid fat content, SFC）、凝胶晶型及硬度的影响。实验结果表明,小烛树蜡添加量≥4%时,掺入低芥酸菜籽油中可制得具有固体性质的油凝胶,添加量为8%时,小烛树蜡使得持油能力（oil binding capacity, OBC）最强;SFC均在2%～6%之间,随着温度的升高,SFC减小;晶型分析表明小烛树蜡低芥酸菜籽油油凝胶主要晶型均在4.70 ?和3.80 ?附近;油凝胶硬度随着小烛树蜡添加量增大而逐渐增大,添加量为10%时小烛树蜡油凝胶硬度适中。为日后小烛树蜡油脂凝胶替代传统起酥油,生产具有高含量不饱和脂肪酸的烘焙食品提供理论基础。