Fractionation of milk fat by short-path distillation

Fractionation of milk fat by short-path distillation changes the chemical composition and physical properties of the resulting fractions. Increases in distillation temperature from 125 to 250 degrees C increased distillate yield from 0.3 to 42.7% (wt/wt). The distillate was enriched in short- and medium-chain fatty acids and low molecular weight acylglycerols, while the retentate was enriched in long-chain saturated and unsaturated fatty acids as well as high molecular weight acylglyerols. As distillation temperature increased, dropping points of the distillate increased. Relative to native milk fat, the solid fat content (SFC) vs. temperature melting profile of the distillate was depressed and that of the retentate was augmented, which correlated with the saturated long-chain fatty acid content in the fractions. Retentate crystallization parameters obtained by fitting the Avrami model to SFC-time data, did not change as a function of distillation temperature, but varied as a function of the degree of undercooling. Changes in microstructure observed by polarized light microscopy also appeared to be solely a function of the degree of undercooling, with no observable differences between retentates obtained at the different distillation temperatures. In addition, no changes in the retentate's free energy of nucleation (deltaGc) as a function of distillation temperature were found. The compressive storage modulus of the crystallized retentate increased as a function of increasing distillation temperature.     

Fractionation and characterization of yeast proteins

Fractional profile of proteins from baker's, brewer's, and alcoholic yeasts was studied, applying a consecutive treatment of commercial biomasses, with solutions with a gradient of ionic strength and pH. It was found that a large part (35-50%) of total proteins from investigated biomasses is extracted by means of 0.01 M KCl, pH 7.0, which together with proteins extracted by means of 0.65 M KCl, pH 9.5, makes the part of the easily extractable proteins (50-64% of the total protein amount). The remaining part of proteins is extracted by means of alkaline solutions only. The amino-acid composition of the isolated fractions indicated that they are suitable for usage as food product ingredients.     

Fractionation and physicochemical characterization of peach gum polysaccharides

One kind of Chinese peach gum was fractionated by different solvent extraction (water followed by alkaline solutions). Chemical analysis showed peach gum polysaccharides were acidic arabinogalactans, mainly composed of arabinose (∼50%), galactose (∼37%) and uronic acid (13–14%), with the molecular weight of ∼4.60 × 10⁶ g/mol according to high performance size exclusion chromatography (HPSEC) analysis. Peach gum solution exhibited typical shear thinning flow behavior properties, K (consistency index) values increased while n (flow index) values decreased with the increasing of concentration. Dynamic sweep tests showed that moduli of peach gum solutions were highly dependent on frequency, concentration and temperature. Water extractable fraction was able to form gel network when concentration was higher than 4%. Alkaline extracted peach gum gave weaker rheological responses, such as lower viscosity at same concentration when compared to the water extractable fraction. Two alkaline extractable fractions exhibited similar intrinsic viscosities of 21.18 dl/g (0.1 M NaOH extractable, AE01) and 21.76 dl/g (0.5 M NaOH extractable, AE05), respectively, while water extractable fraction (WE) formed aggregate in water at low concentration. All fractions extracted from peach gum exudates showed better emulsion capacity and stability than gum arabic and fenugreek, which could be used in food industry to replace or partially replace gum arabic.     

Fractionation and characterization of tartary buckwheat flour proteins

Protein fractions (albumin, globulin, prolamin and glutelin) were extracted from defatted tartary buckwheat flour. Albumin was the predominant protein fraction (43.8%) followed by glutelin (14.6%), prolamin (10.5%), and globulin (7.82%). Albumin was relatively rich in histidine, threonine, valine, phenylalanine, isoleucine, leucine and lysine. Globulin had high levels of methionine and lysine. Prolamin was high in histidine, threonine, valine, isoleucine, and leucine. Glutelin was rich in histidine, threonine, valine, isoleucine, and leucine. SDS–PAGE analysis, under non-reductive and reductive conditions, showed that disulfide bonds existed in the four fractions. Non-reduced albumin showed major bands at 64, 57, 41, and 38 kDa, and globulin at 57, 28, 23, 19 and 15 kDa. Reduced albumin and globulin shared two common bands at 41 and 38 kDa. Reduced prolamin showed major bands at 29, 26, 17 and 15 kDa. In vitro pepsin digestibility of the four fractions (from high to low) was: albumin > globulin > prolamin and glutelin.     

Fractionation and structural characterization of haw pectin oligosaccharides

Although haw pectin and its hydrolysates are believed to have various functions in food industries, correlation of the structure with the functionality of oligomers has not yet been clarified. In the present study, haw pectin oligosaccharides were fractionated, and their structural characterizations were analyzed. The results showed that ultrafiltered haw pectin hydrolysates yielded 11 fractions (F1~F11) on a DEAE-Sephadex A-25 column chromatograph. One fraction (F1) was galacturonic acid, whereas other fractions (F2~F11) were oligosaccharides. Structural analysis using nuclear magnetic resonance and gas chromatography with mass spectrometry showed that these oligosaccharides (F2~F11) are oligogalacturonide family with degrees of polymerization of 2–11, linked by α–(1 → 4) linkages. The information obtained could be used in the exploitation and utilization of haw pectin and its derivational oligomers.     

油脂稳定性与抗氧化方法的研究

本文报道了猪油、花生油、鱼油的自动氧化情况和几种抗氧化剂对它们进行抗氧化的效果。硫醚类物质硫代二丙酸(TDPA)及其二月桂酯(DLTP)与常用的酚类抗氧化剂叔丁基羟基茴香醚(BHA)、二叔丁基对甲酚(BHT)、没食子酸丙酯(PG)以及天然物愈创树脂(GR)、茶多酚(TPP)等相比,能更有效地降低油脂氧化性酸败的主要指标过氧化值(POV)的增高。     

可食性南瓜纸的制备及其性能研究

以南瓜为基材,海藻酸钠为增稠剂,甘油为增塑剂,制备了可食性南瓜蔬菜纸。研究了南瓜质量分数、海藻酸钠添加量和甘油添加量对南瓜纸各项性能的影响。结果表明:南瓜质量分数、海藻酸钠质量分数、甘油体积分数对南瓜纸各项性能有较显著的影响,并确定了各因素的添加范围:南瓜质量分数15%²5%,海藻酸钠质量浓度0.525%,海藻酸钠质量浓度0.5¹.5 g/L,甘油体积分数0.1%1.5 g/L,甘油体积分数0.1%⁰.2%;得出干燥的最佳工艺条件:干燥温度为60℃,干燥时间为6 h。     

Guava seed storage protein: Fractionation and characterization

In the present work, guava seed storage proteins have been fractionated and characterized. Glutelins (86-90 g/100 g) and globulins (≈10 g/100 g) are the main components of the protein extract. Albumins and prolamins are minor components (≈2 g/100 g). Guava seed glutelin extracts, like rice and amaranth glutelins, are legumine-like proteins that, due to their solubility properties, have to be extracted using extreme pH (borate buffer, pH 10, Gt-Bo; NaOH pH 12 Gt-Na), denaturing (borate buffer plus sodium dodecyl sulfate, Gt-BoSDS) or reducing conditions (borate buffer plus 2-mercaptoethanol, Gt-BoME; borate buffer plus sodium dodecyl sulfate and 2-mercaptoethanol, Gt-BoSDSME). The highest yield was obtained with SDS extraction, suggesting that proteins in the seeds form aggregates stabilized mainly by non-covalent interactions. Glutelins are mainly composed of 65 and 67 kD subunits, with a lower proportion of 55 kD subunits. These subunits are formed by disulfide bond-linked polypeptides with molecular masses 40-45 kD, 22-27 kD and 23-25 kD, respectively. The guava seeds protein isolate (GSI) exhibited a polypeptide profile very similar to that of the glutelin fraction.The guava seed could be an alternative source of protein for human and animal consume, additional to this to solve at least in part the pollution problem that fruit processing industry has for discarding this material.     

Availability of macro and microelements from edible domestic waste fed to sheep

Young Awassi rams fitted with rumen cannula and T-shaped cannulas in duodenum and terminal ileum were used to study net absorption of calcium, phosphorus, magnesium, zinc, manganese, and copper from edible domestic waste in comparison with a conventional concentrate diet. Mean net absorptions (% of intake) of calcium, phosphorus, and magnesium from edible domestic waste and control diets were 15.3, -.9; 54.4, 37.0; and 46.4, 58.8. The small intestine was the major site for calcium and phosphorus absorption and the rumen for absorption of magnesium. Net absorption of zinc, manganese, and copper was low in both diets, probably as a result of excessive supply and low physiological demands. There was a net gain of manganese and copper and a net loss of zinc in the stomachs. In addition to potential for energy and protein, edible domestic waste supplies macro and microelements for ruminants, and thus, it can be regarded as a complete concentrate diet.     

壳聚糖/香菇多糖可食性膜的性能研究及表征

采用壳聚糖为主要成膜材料,添加一种生物活性成分香菇多糖,以甘油为增塑剂,采用流延法制备新型的可食性复合膜。测定香菇多糖的含量对膜材料性能的影响,并对复合膜进行结构表征。结果表明,随着香菇多糖含量的增加,复合膜的抗拉强度从24.61MPa增加到32.14MPa、断裂延伸率从15.07%降低到4.57%;水溶性逐渐增加,最高时达7.04%;阻氧性先升高后趋于平稳,在香菇多糖含量为1.0%时最佳,过氧化值低至4.28g/100g;水蒸气透过率先降低后升高,在香菇多糖含量为0.75%时达到最小值0.1322g·mm/(m2·h·k Pa)。红外及XRD分析显示复合膜各组分良好相容。      

几种特种食用油脂的营养价值及功效

分别介绍了油荼籽油、红花籽油、米糠油、葡萄籽油等几种具有代表性的特种油脂的化学组成及特点,并分析和总结了各特种食用油脂的营养价值与功效。     

近红外光谱技术在油脂检测中的应用

近红外光谱技术作为一种快速检测技术 ,在食品行业已应用于粮食检测、果蔬加工和肉制品加工等领域 ,为食品质量管理作出了较大贡献 ,本文就近红外光谱技术在油脂油分含量及其品质检测方面的应用加以综述。     

Comparisons of 13 edible gum-hydrate fat substitutes for low fat Kung-wan (an emulsified meatball)

In this study, we used edible gum-hydrates to replace pork fat in developing low fat Kung-wan, an emulsified meatball. A one-way completely randomized design was adopted for comparing three controls and 13 edible gum-hydrates as fat substitutes. Results indicated that replacing fat with water caused lower cooking yield, smaller diameter, inferior sensory qualities and lower texture profile analysis indices. Eight gum-hydrates produced Kung-wans with higher cooking yields than the positive control (ConFa). Seven gum-hydrates produced low fat Kung-wans with similar texture profile analysis indices as ConFa. Six gum-hydrates produced products with lower Hunter-B value, while two produced products with similar color as ConFa. Six gum-hydrates produced products with similar sensory qualities as ConFa. Overall, κ-carrageenan (Kcarr), sodium alginate with CaCO₃, curdlan gum and locust bean gum (LBG), appeared to be good fat substitutes for making low fat emulsified meatballs. Within these, Kcarr and LBG were better.     

Mechanical and barrier properties of sodium caseinate–anhydrous milk fat edible films

Edible films were cast from solutions of sodium caseinate (NaCAS) and from emulsions of this protein with anhydrous milk fat (AMF). The moisture sorption isotherms, mechanical properties [tensile strength (TS) and elongation] and water vapour and oxygen permeabilities were determined for films based on NaCAS as a function of AMF concentration. AMF concentration significantly affected TS (P < 0.001) and elongation (P < 0.05). The increase of lipid content led to a loss of mechanical efficiency, but had little influence on water vapour barrier properties. No significant difference (P > 0.05) occurred between oxygen permeability of films at each lipid concentration.     

决策阶段食用油厂投资的控制

食用油厂投资决策是油厂投资行动的准则, 油厂建设决策正确与否,直接关系到油厂建设的成败,关系到油厂造价的高低、质量的好坏及投资效益优劣的全过程.只有投资决策正确才能使油厂的投资得到有效地控制.     

迷迭香添加鱼肉蛋白可食膜的制备与特性

以鲢鱼肉为主要原料制备蛋白可食膜,测定了迷迭香抗氧化剂添加对膜理化性质和抗氧化性能的影响。结果表明,利用鲢鱼肉可以制备成无色透明的蛋白可食膜,鱼肉蛋白膜的机械性质和水蒸气透过性（WVP）主要由肌原纤维蛋白含量决定,在鱼种间的差异并不显著。添加迷迭香抗氧化剂对鱼肉蛋白膜的机械性质和WVP影响不显著,但对膜的阻隔紫外线能力和抗氧化性能有提高作用。将蛋白膜包装的鳗鱼肉在37℃下放置12h,与未包装样品相比,鳗鱼肉的POV和TBARS的增加明显得到抑制,而添加迷迭香会进一步提高其抑制效果。     

Differential thermal analysis as a control instrument in edible fat hydrogenation

Summary. The use of differential thermal analysis for following the progressive hydrogenation of ground nut oil with a view to giving an end product of consistent quality is described. the technique appears to be promising as a method for determining the solid fat index at various temperatures and compares favourably with dilatometry in speed, reproducibility of results and the amount of information available from any one analysis.     

Fractionation and partial characterization of non-pectic polysaccharides from yellow mustard mucilage

A polysaccharide fraction was isolated from yellow mustard mucilage using pectinase hydrolysis and ammonium sulphate precipitation. Results indicated that ammonium sulphate precipitation produced a material with more glucose and less uronic acid compared to ethanol precipitation. Chemical, structural and rheological properties of the isolated fraction were investigated. Chemical analysis revealed that this material was mainly composed of glucose (61.1%); however, other sugars were also found, including galactose (13.8%), rhamnose (4.5%), mannose (13.1%) and xylose (7.5%). It also contained 6.9% of uronic acid. Methylation analysis indicated that this polysaccharide fraction consisted mainly of a β-1,4 linked glucosyl backbone. Rheological tests showed that the polysaccharide exhibited strong shear-thinning flow behaviour and weak gel structure. When the aqueous weak gel solution was subjected to an acid environment, the gel structure became stronger compared to more neutral conditions. This polysaccharide exhibited thermal stability over the temperature range from 5 to 90 °C.     

Residues of lindane in plasma and fat of sheep after dipping

Ten 5-6 year-old unshorn ewes were dipped in a 0.025% lindane solution. Lindane residues in fat and plasma were analysed by gas liquid chromatography with an electron capture detector. The sensitivity of the method was 0.02 microgram/g for fat and 0.005 microgram/ml for plasma. Blood samples of 5 sheep were collected up to 84 days. The highest concentration of lindane detected in plasma was 107 +/- 37 ng/ml, 48 h after treatment. The disposition of lindane in plasma was studied by linear regression. Omental fat samples were removed by biopsies at 7 or 14 day intervals for 154 days. Fat concentrations of lindane were very high, respectively 30.46 +/- 14.6 ug/g, 8.09 +/- 4.57 micrograms/g, and 1.72 +/- 0.81 micrograms/g, 7, 28 and 70 days after dipping. In plasma and fat, the coefficients of elimination calculated by linear regression were similar (0.00190 +/- 0.00053 h-1 for plasma, 0.00196 +/- 0.00031 h-1 for fat). The tolerance recommended in France (2 micrograms/g in fat) was obtained 59.7 +/- 9.7 days after this treatment.