Application of enzyme-assisted aqueous fat extraction to cocoa fat

An enzyme-assisted aqueous fat extraction method was used to extract fat from dry cocoa beans. The beans were dehulled and finely ground. Samples were mixed with water in predetermined ratios. A protease and an enzyme with high activities of both cellulase and hemicellulase were added at 1% of the sample weight, mixed, and incubated for about 6 h at 37°C. The treated samples were then extracted by a water flotation technique. The preextraction treatment with enzymes effectively increased fat yield by about 26%. The observation suggests that the enzyme-assisted aqueous fat extraction method could improve the efficiency of rural fats and oils technologies currently in use in many developing countries.     

A rapid method for extraction of total lipids from whey protein concentrates and separation of lipid classes with solid phase extraction

A modified procedure for extraction of total lipids from whey protein concentrates was developed such that stable emulsion with extracting solvents was avoided and the solvent system remained monophasic. Nonlipid contaminants from the extract were removed using gel filtration instead of traditional aqueous washing to prevent any loss of polar lipids. The extraction of total lipids by the modified procedure was complete and comparable with a reference procedure. Traditional thin-layer chromatography is tedious and more qualitative than quantitative for lipid class separation. Total lipids were further separated into free fatty acids, phospholipids, cholesterol ester, triacylglycerol, cholesterol, diacylglycerol, and monoacylglycerol, using modified solid phase extraction procedure. Columns with 2 g amino propyl packing allowed separation of up to 80 mg of total lipids into lipid classes gravimetrically. The values for anhydrous milk fat for all lipid classes agreed with those in the literature. Separation of total lipids into lipid classes with solid phase extraction is easy, quantitative, and can also be performed on a preparative scale.     

Enzyme-assisted aqueous extraction of fat from kernels of the shea tree,Butyrospermum parkii

Chemical characteristics of kernels of the shea tree (Butyrospermum parkii) from Ghana were determined in order to design and evaluate studies on a traditional enzyme-assisted fat extraction of the kernels. The effectiveness of a number of cellular degrading enzymes in assisting the shea fat extraction were also tested by treating meals of the kernels with one or more of these enzymes before extraction and comparing the yield with control extractions. Proximate composition of the kernel on dry-matter basis was: total lipids, 59.04%; crude fat, 54.85; protein, 7.81%; total carbohydrates, 34.77%; ash, 2.57%. Starch content was 7.59%; hemicellulose, 10.84%; cellulose, 5.95%; and pectic substances, 2.93%. Total fiber content was 20.35%. The fat extracted by the Soxhlet method was pale-yellow in color and solid at room temperatures. Its physicochemical characteristics were: melting range, 34–36°C; iodine value, 58.53; saponification value, 180.37; and unsaponifiable matter content, 7.48%. The predominant fatty acids were: palmitic (3.55%), stearic (44.44%), oleic (42.41%), linoleic (5.88%) and linolenic (1.66%) acids. The enzyme-assisted extraction tests showed increases in extraction yield when the shea kernel meals were treated with the enzyme(s) before extraction. An increase of about 20% was realized when a protease and an enzyme with both cellulase and hemicellulase activities were used together. These observations confirmed the fact that the shea kernel is a rich source of fat. They also indicate the possibility of improving shea kernel extraction processes by pretreating the kernel meal with cell structure-degrading enzymes.     

毛氏提取法测定液体乳制品中脂肪含量

建立了毛氏提取法测定液体乳制品中脂肪的方法,并分析了不同方法的系统性差异。建立的方法与GB5409—1985中罗兹哥特里法比较,具有准确、精密度高、易于操作的优点,能满足液体乳制品中脂肪的测定要求。     

Correction of dietary fat availability estimates for wastage of food service deep-frying fats

Because of the renewed interest in the consumption of hydrogenated fats, reliable estimates of the dietary fat available to the United States population require correction for the considerable amount of deep-frying fats used in food service operations that are discarded after use and thus are not available for consumption. We estimated this fat wastage from food service sources from published data on fat exchange during cooking and on numbers of specific entrees purchased away from the home by United States households. Among food items considered, fat rendered from hamburgers and chicken contributed substantially to the total gross fat available for discard; fried chicken, french fries and doughnuts accounted for a large portion of total fat uptake by foods. To calculate waste frying fat, expressed as a percent of net waste fat, we subtracted fat uptake by foods from the total visible frying fat available for usage and from the level of gross fat available for discard. Dividing the resulting values gave a percent waste frying fat of 60%. For calculation of fat available for consumption, we recommend that contributions from deep-frying fats be reduced by 50% of the total available to correct for wastage. This value is conservative and representative of actual experience of major food service operations and agrees closely with estimates derived from spent grease recovery reported in the United States. Presented at the 1992 AOCS Annual Meeting, May 10–14, 1992, Toronto, Ontario, Canada.     

Enzyme-assisted aqueous extraction of shea fat: A rural approach

The use of enzyme-assisted partial hydrolysis as a preextraction treatment in a rural shea fat extraction process to improve upon the extraction rates of the process was explored following an observed possibility in a preliminary investigation. Finely ground shea kernel meal samples were mixed with water in predetermined ratios and heated to inactivate any enzymes present. A crude protease and an enzyme with both hemicellulase and cellulase activities were added and mixed, also in predetermined concentrations. The suspensions were incubated in a waterbath shaker at temperatures ranging from 30 to 45°C for specified periods of time. The treated meal samples were then extracted using an adapted traditional aqueous extraction process. At optimum meal-to-water ratio of 1:2, enzyme concentration of 1%, the natural pH of the meal (about 5.3), and incubation time of 4 h, the enzyme treatment increased the extraction rate from about 40% in the typical traditional system (control) to about 75%, of the total fat content (estimated by the Soxhlet method). The enzyme-treated meal samples were very easy to extract as there was no need to cream or whip out the fat, as is laboriously done in the traditional process. The extracted fat samples had apparently less unsaponifiable matter content and slightly less free fatty acid content and peroxide value, compared to samples from the typical traditional process and, in some cases, the Soxhlet extracted samples. The observations confirmed the results of the preliminary investigations and suggest that the enzyme-assisted preextraction treatment could significantly improve upon the aqueous shea fat extraction process.     

Microscale recovery of total lipids from fish tissue by accelerated solvent extraction

A number of techniques are available for the extraction of lipids from a variety of tissues; however, conventional methods are characteristically labor intensive, typically involve large volumes of toxic solvents, and usually require at least 1 g of tissue. With the availability of accelerated solvent extraction (ASE) technology, the opportunity exists to modify classical lipid extraction techniques such that automated high-pressure, high-temperature extractions may be performed with the use of far smaller volumes of costly and harmsul solvents. Moreover, the high extraction efficiency attainable by ASE suggests that significantly less tissue would be required than is routinely used. This paper describes the adaptation of previously developed lipid extraction solvent systems for use with ASE toward the purpose of extracting total lipids from 100 mg of fish tissue. The efficacy of three solvent systems for lipid extraction from representative fish tissues, including a standard reference material, was explored using gravimetry and FA analysis by GC. A TG was used as a surrogate to monitor overall method performance. The findings herein demonstrate that microscale ASE represents an effective and efficient alternative to traditional lipid extraction techniques based on quantity and composition of extracted lipid, surrogate recovery, and precision.     

附子中总生物碱的提取工艺及含量测定

采用索式回流提取法用乙醇提取附子总生物碱,采用酸碱滴定法测定附子中总生物碱的含量。结果表明,总生物碱的最佳提取工艺:水的倍数为10,时间为1.5 h,提取次数为2次。     

Recent developments and prospects in the extraction,composition, stability,food applications,and in vitro digestion of plant oil bodies

Oil bodies (OBs) are micron- or submicron-sized sub-organelles widely found in plants seeds and nuts. The structure of OBs is composed of a core of neutral lipids covered by a phospholipid-protein layer, which ensures the stability of OBs under extreme environmental conditions and further protects core lipids as energy reserves. As naturally pre-emulsified oil-in-water emulsions, OBs have been gradually applied to replace synthetically engineered oil droplets. In this paper, the recent research on the extraction, composition, stability, food applications, in vitro digestion, and future perspectives of plant OBs were reviewed. Recent studies have focused on the large-scale extraction techniques and OBs surface protein identification and function. Electrostatic deposition and viscosity effect of polysaccharides significantly improve the stability of OBs emulsions. OBs have broad application prospects in replacing milk fat droplets, as fat replacers and delivery vehicles, and fabricating emulsion-gels, oleogels or edible films. Notably, oleosins present a potential allergen risk. OBs are digested slowly, resulting in increased satiety and effectively helping to reduce calorie intake, but this can negatively affect the bioaccessibility of nutritional compounds in OBs. When OB as a delivery vehicle, its natural structure may be disrupted, whereas OBs-based delivery system facilitates the bioaccessibility of hydrophobic active compounds.     

Total fat analysis in milk- and soy-based infant formula powder by supercritical fluid extraction

A rapid method for the determination of total fat in infant formula powders using a commercially available supercritical fluid extraction (SFE) instrument was evaluated. The matrices examined were Standard Reference Material SRM 1846 Infant Formula (NIST) and commercial milk- and soybased infant formula powders. Method verification and validation were done by linear regression analysis using the Method of Standard Additions. A Data Quality Objectives (DQO) format was used to define and evaluate the performance characteristic parameters of the instrumental total fat analysis fy SFE. A peer validation study showed excellent agreement with the declared labeled percentage fat values and reproducibility among three participating laboratories. The laboratory relative SD (RSD _R %) is within Horwitz's limits of acceptability and the HORRAT ratio criteria at the level of the analyte analyzed. Linear regression analysis of all infant formula matrices spiked with added fat showed that the SFE instrument response was due only to the added analyte. By integrating the DQO process with a readily available certified reference material, along with reproducibility indicated by two outside collaborating laboratories, we established verification and validation of the accuracy of the data obtained by SFE.     

Comparative study of total lipids in beef using chlorinated solvent and low-toxicity solvent methods

Nine extraction methods (three using chlorinated and six nonchlorinated solvents) were compared for determining lipids in samples of low-(<5%) and high-fat (>20%) ground beef. The nine methods investigated were: Folch, Lees, and Sloane Stanley (FLS); Bligh and Dyer (BD); Bligh and Dyer modified by Undeland, Harrod, and Lingnert (BDU); Bligh and Dyer modified by Smedes (BDS); Hara and Radin (HR); Schmid, Bondzynski, and Ratzalaff (SBR); Roese-Gottlieb (RG); Burton, Webb, and Ingold (BWI); and Soxhlet (SE). The BDS and HR methods do not include solvents such as chloroform and methanol and can be recommended for meat samples that have both low and high fat content. If the use of organic solvents is not critical, the FLS and the BD extraction methods yield the highest results, but the FLS is more expensive owing to the high amount of solvent required. Without considering the toxicity of the solvents, the three BD extraction methods provided the best yields.     

香椿叶中总黄酮的提取工艺研究

研究了溶剂法提取香椿叶总黄酮的工艺条件。在单因素试验的基础上,用正交实验法对香椿叶总黄酮的提取工艺进行优选,考察乙醇体积分数、固液比、提取时间、浸提温度对香椿叶总黄酮提取率的影响。结果表明,在浸提3次条件下,得到叶片总黄酮最佳工艺条件为:乙醇浓度80%、固液比为1∶10(g/mL)、提取温度80℃、提取时间2 h,在此条件下香椿叶片总黄酮提取率为61.13%;叶轴总黄酮最佳提取条件为:乙醇浓度70%、固液比为1∶10(g/mL)、提取温度80℃、提取时间1 h,在此条件下香椿叶轴总黄酮提取率为71.71%。     

超声波辅助气提法测定废水中的总氰化物

建立了超声波辅助气提法测定废水中总氰化物的方法。实验结果表明,含氰废水在60～70℃的热水浴中进行超声波辅助气提,空气流量为1.0 L/min,气提时间15 min,所得结果的准确度和精密度满足监测要求。     

接骨木茎总黄酮的提取条件研究

用乙醇回流提取接骨木茎总黄酮,用分光光度法进行含量测定。考察了料液比、乙醇浓度、提取时间、提取温度对接骨木茎总黄酮提取率的影响。结果表明,最佳提取工艺条件为：料液比1∶40（g/mL）,乙醇浓度50%,提取时间1.5 h,提取温度70℃,提取次数1次,提取率为0.566%。     

茵陈总多酚的超声提取工艺研究

用超声辅助提取法提取茵陈中的总多酚,考察了提取溶剂浓度、料液比、提取温度和时间对总多酚提取率的影响。结果表明,用60%乙醇作提取溶剂,在固液比为1∶10(m∶V),70℃下超声提取100 min,总多酚提取率为0.503 6%。     

马占相思树叶总多酚的微波提取工艺研究

研究微波提取马占相思叶中总多酚的工艺条件,以总多酚提取量为参考指标,考察乙醇浓度、固液比、微波提取时间、提取温度对马占相思叶总多酚提取量的影响。得到的最佳工艺条件为:20 g原料,以料液比1∶10加入50%的乙醇溶液,在80℃下每次微波提取35 min,提取3~4次。在此条件下,每克马占相思叶可提取总多酚36.368 1~43.414 7 mg。     

超声波浸提-喹钼柠酮重量法测定化肥中磷的实验研究

通过实验,考察了超声波浸提化肥中磷的实验条件,建立了超声波提取肥料中的有效磷和水溶性磷、利用喹钼柠酮重量法测定磷的方法。与现行国家标准相比,分析时间大大缩短,磷测定的精密度与准确度也有所改善,可适用于肥料中磷的测定。     

Supercritical fluid extraction of lipids from deep-fried food products

A supercritical fluid extraction (SFE) method is described for extracting lipids from fried-food samples. Response surface analysis was used to study the effects of variables, including pressure, temperature, flow rate, and modifier (methanol) on lipid extraction by SFE. The analysis of variance for the response variables indicated that the models developed were satisfactory with coefficients of determination of 0.95 and 0.92 for chicken nuggets and potato fries, respectively. The models predicted that increasing the pressure increased the percentage lipid extracted for both chicken nuggets and potato fries. In addition, the pressure by temperature interactions were significant for chicken nuggets and potato fries. Slight differences in fatty acid composition were observed between SFE and the Goldfisch method. The SF extracts contained traces of C_12:0, C_20:0, and C_24:0 in chicken nuggets and C_14:1, C_18:3, C_22:0, and C_23:0 in potato fries, respectively, which are not found in the Goldfisch extracts. The optimal conditions for extraction are: 53 MPa, 150°C, 4 mL/min, and 10% modifier for chicken nuggets and 53 MPa, 150°C, 3 mL/min, and 0% modifier for potato fries. To duplicate the results of exhaustive Goldfisch extraction with petroleum ether, SFE conditions of 44 MPa, 80°C, 3 mL/min, and 0% modifier were used to produce similar results for both chicken nuggets and potato fries.     

超声波提取海红果中总多酚的工艺研究

采用超声波辅助甲醇提取法从海红果中提取总多酚,研究了提取温度、提取时间、料液比等对总多酚提取量的影响。结果表明,超声提取海红果中总多酚的最佳提取工艺条件为:提取液甲醇浓度60%,料液比(g/mL)为1∶12,在55℃下提取50 min。     

The influence of food emulsifiers on fat and sugar dispersions in oils. I. Adsorption,sedimentation

The adsorption isotherms of several emulsifiers to fat and sugar crystals dispersed in oils have been determined. Further, the influence of the emulsifiers on the interactions between the crystals has been estimated in sedimentation experiments, where an increased sediment volume due to adsorption corresponds to an increased adhesion between the crystals andvice versa. Most of the emulsifiers examined adsorb weakly to fat crystals and form tight monolayers, resulting in increased adhesion between the crystals at high concentrations. On the other hand, loosely packed layers are formed at low concentrations, and a decreased adhesion is observed. Unsaturated monoglycerides and phospholipids cause a decrease in adhesion for all concentrations examined. The emulsifiers adsorb more strongly to sugar crystals than to fat crystals and form tightly packed monolayers with hydrocarbon chains directed to the oil. The crystals are then stabilized sterically—the adhesion between them is weaker and the sediments are more compact. At low concentrations, the opposite behavior often occurs. Monoglycerides interact in a specific way with sugar and cause increased adhesion between the crystals for all concentrations examined. Phospholipids reduce the adhesion between sugar crystals, resulting in much denser sediments. Saturated monoglycerides in amounts over the solubility limit tend to precipitate as a network between fat or sugar crystals, which causes bulky sediments and results in better stability against oiling out.