Thermal degradation of prions in the presence of fats: Implication for oleochemical processes

Bovine tallow is widely used as raw material for oleochemical processes, i.e. the manufacturing of fatty acids and glycerol and their derivatives. The basic oleochemical process, i.e. the hydrolytic fat splitting under industrial conditions of 200–260 °C at corresponding pressure and a minimum residence time of 20 min, is considered to guarantee the safety of all tallow‐derived products. As to the present day no experimental data on the safety of fatty acids and glycerol in case of a hypothetical contamination of tallow with TSE agents under technically relevant conditions are available, the intention of this study was to provide quantitative data for the destruction of prions. This short communication reports the first part of a research project simulating prion inactivation under manufacturing conditions of the upper part of industrial fat‐splitting columns (fatty acid regime) on a laboratory scale. To establish worst‐case destruction factors, the degradation of prion protein was analysed in dependence upon temperature. The industrial process conditions of the fatty acid regime of hydrolytic fat splitting provide an additional safety factor of at least 1×10⁷, confirming that all fatty acids can be regarded as safe, irrespective of their origin.     

Effect of PUFA at sn‐2 position in dietary triacylglycerols on the fatty acid composition of adipose tissues in non‐ruminant farm animals

The influence of the distribution of polyunsaturated fatty acids on the glycerol backbone of dietary triacylglycerols on the fatty acid profile of adipose tissue and muscle phospholipids was investigated in growing‐finishing pigs (48) and broiler chicken (84). The animals were fattened on barley/soybean meal diets supplemented with a blend of soybean oil and beef tallow, either in the ratio 3:1 w/w (high‐PUFA) or 1:3 w/w (low‐ PUFA). Part of the high‐ and low‐PUFA blends was chemically interesterified to randomly distribute all fatty acids over the three positions of the glycerol. Thus, two sets of diets of identical overall fatty acid composition, but differing in the distribution of fatty acids in the triacylglycerols, were fed. Growth performance and carcass composition were neither affected by fatty acid composition nor by randomisation of dietary fats in either animal species. Apparent digestibility of energy was slightly lower in pigs fed the low‐PUFA blends. Fatty acid profile of subcutaneous fat of pigs and broilers as well as of internal body fat (lamina subserosa) and muscle phospholipids of pigs varied according to the dietary fatty acid composition but was not affected by randomisation of dietary fats. These findings are explained in terms of the hydrolysis of TAG during transport of lipids from enterocytes to adipose tissue cells and the continuous lipolysis and re‐esterification of fatty acids that take place in adipose tissue cells.     

Prion decontamination during the oleochemical process of fat hydrogenation

The human food and animal feed industry and even oleochemical manufacturing processes might be exposed to contamination from products of BSE‐infected cattle. Although the most important oleochemical raw material, i.e. tallow, is not considered to be a causal factor for BSE, the potential risk associated with tallow‐derived products has to be evaluated in the light of the specific production process. The main production process for oleochemicals, i.e. hydrolytic fat splitting of tallow yielding glycerol and a mixture of crude fatty acids, guarantees prion‐free products, safe for human consumption [1]. Fatty acids, however, are not necessarily produced by hydrolytic fat splitting. In order to evaluate these fatty acids with regard to prion safety, we analysed the industrial conditions of catalytic fat hydrogenation, which is widely applied to improve storage and flavour stability of fatty acids. Quantitative data for the degradation of the pathological prion protein and the inactivation of prion infectivity are presented. A risk assessment calculation demonstrates that the industrial conditions of fat hydrogenation are sufficiently effective to reduce the risk of BSE contamination to an acceptable minimum.     

Risk assessment for fat derivatives in case of contamination with BSE

Prion diseases are not only of outstanding scientific interest but have also enormous economic impact. In particular, the human food and animal feed industry and even oleochemical manufacturing processes are afflicted. In the oleochemical industry, bovine edible tallow is widely used as raw material for the production of fatty acids, glycerol, and their derivatives. Although there is no evidence that tallow has been a causal factor for BSE nor that infectivity partitions preferentially with tallow, the potential risk associated with tallow‐derived products has to be evaluated in the light of the specific production process. To the present day, no experimental data under technically relevant conditions are available on the safety of fatty acids, glycerol, and their derivatives in the case of a hypothetical contamination of tallow with prions. A risk assessment calculation is provided here based on quantitative data for the degradation of the pathological prion protein as well as the inactivation of prion infectivity. It can be concluded that the industrial conditions of the basic oleochemical process of hydrolytic fat splitting constitute an effective means for reducing the risk of TSE contamination to an acceptable minimum. All industrial tallow‐derived products can be regarded as safe, independently of their origin.     

Some structural investigations on phospholipids from membranes

A complete chemical characterization of phophatidyl glycerol from green leaves and algae demonstrated that 1-linoleneoyl-trans-Δ³ represented the major molecular species and its occurrence appeared to be related to photosynthesis. Beef-heart cardiolipin was demonstrated to be identical to synthetic diphosphatidyl glycerol. Chemical structures of synthetic amino acid esters of phosphatidyl glycerol were compared with those of amino acid and glucosamine containing phospholipids from bacterial cell membranes. The molecular species of lecithin from animal tissues were recognized and the influence of dietary fats on their composition was determined. Physical characteristics of natural and synthetic phospholipids indicate that nature is eloquent to preserve the properties offered by particular fatty acid combinations in the phospholipid molecule. Mammalian tissues were found to contain phospholipase A activity which produces two structurally isomeric monoacyl-phosphoglycerides. Utilizing five isomeric lysolecithins of known structure micro methods involving enzymic hydrolysis were developed to distinguish among these isomers. Lysolecithins from different natural sources were demonstrated to consist of both 1-acyl-glycero-3-phosphorylcholine and 2-acyl-glycero-3-phosphorylcholine. In connection with the nonrandom distribution of fatty acids of different apolarity at the two positions of phosphoglycerides, the various metabolic pathways of lysolecithin enantiomers in red cell ghosts, yeast and liver were investigated using different doubly-labeled substrates.     

The Conversion of Low Grade Tallow into Biodiesel-Grade Methyl Ester

The conversion of low grade tallow with free fatty acid contents of 11.0–26.0% into biodiesel-grade methyl ester was investigated on a laboratory scale. Methanolysis of low grade tallow could not be carried out by the standard base-catalysed process, because the high free fatty acid content of low grade tallow caused incomplete methanolysis and prevented phase separation. The problem was able to be partly overcome by adding more potassium hydroxide to neutralise the free fatty acids, 50–100% more methanol and some water to promote phase separation. However, even with the modified method only about 55% of the starting material could be recovered as methyl ester and this fell to 35 and 14% when the free fatty acid content of tallow increased to 20 and 26%, respectively. It was shown that yield losses were caused mainly by the dissolution of methyl ester in the glycerol phase, and to a lesser extent to hydrolysis of the triglycerides. In order to prevent yield losses caused by the dissolution of methyl ester in the glycerol phase the possibility of esterifying free fatty acids either before or after base catalysed methanolysis was investigated. Both methods involving methanolysis and esterification gave good conversions of low grade tallow to methyl ester, and in each case yields above 90% were obtained by relatively simple processes.     

Volatile fatty acids in flavors of potatoes deep-fried in a beef blend

The volatile free fatty acids were analyzed in commercial french- fried potatoes that had been deep- fried in beef tallow- hydrogenated vegetable oil shortening. The results showed that many of the volatile fatty acids present in beef tallow were transferred to the potatoes. Of the fatty acids derived from beef tallow, butanoic, 2-methylbutanoic, 3- methylbutanoic, heptanoic, 4-methyltanoic, and nonanoic acids were present in concentrations above their respective thresholds, and should contribute to tallow- like flavors. Several unsaturated volatile fatty acids also were identified, and they should contribute to the general deep- fried potato flavor.     

内蒙古地区万寿菊植株营养成分分析

对内蒙古地区种植的万寿菊进行了营养成分分析。结果显示,本地区万寿菊含有丰富的粗蛋白、粗脂肪以及粗纤维等多种营养成分,除此之外还含有2种半必需氨基酸、7种必需氨基酸和8种非必需氨基酸。     

Thermal stability of some flavonoids and phenolic acids in sheep tallow olein

In this study, the thermal stability of some phenolic antioxidants including flavonoids (quercetin and catechin) and phenolic acids (gallic acid, tannic acid, ellagic acid and caffeic acid) in tallow olein was investigated. Tallow olein fractionated from sheep tallow fat was used as a medium to study the antioxidant activity at 120, 140, 160 and 180°C. In order to extract tallow olein, a three‐stage fractionation method was performed on sheep tallow fat at the constant temperatures of 25, 15 and 5°C using acetone as a solvent. The results suggested that quercetin and ellagic acid had the highest thermal stability amongst others, while gallic acid and caffeic acid exhibited the least thermal stability. Practical applications: The sheep tallow fat has been primarily used in soap manufacturing and its application as an edible fat has been limited due to its high content of saturated fatty acids. Extraction of the liquid phase of tallow fat (tallow olein) by fractionation reduces its long‐chain saturated fatty acid content to an acceptable level for edible consumption. The fractionation process, as negatively affects the stability to autoxidation, should be followed by stabilisation with antioxidants. The recent interest in natural antioxidants encouraged the authors to investigate the thermal stability of phenolic antioxidants in tallow olein. It is necessary to determine the thermal stability of antioxidants to predict their appropriateness to be used in high‐temperature applications such as deep frying. Fractionation and stabilisation with appropriate antioxidants are the important steps to utilise tallow olein as an edible oil for different applications in salad formulations, cooking and frying.     

Lipids of dermatophytes II. Effect of growth condition on the lipid composition and membrane transport ofMicrosporum gypseum

Supplementation of glucose-containing medium with ethanol and replacement of glucose by glycerol in the Sabouraud’s growth medium ofMicrosporum gypseum altered the levels of total phospholipids as well as their apolar and polar head groups. The levels of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) increased under these growth conditions; also, the ratio of unsaturated/saturated phospholipid fatty acids decreased on ethanol supplementation but increased in the presence of glycerol. Steady state accumulation of labelled amino acids (glycine, lysine and aspartic acid) was affected under these conditions.     

Distribution of cholesteryl esters and other lipid in subcellular fractions of the adrenal gland of the pig

Total lipids from whole pig adrenal glands as well as from their mitochondria, microsomes, liposomes, and cell sap were extracted and fractionated first into neutral lipids and phospholipids. The highest percentage of neutral lipids was found in the cell sap, and the lowest in the microsomal fraction. Neutral lipids were subfractionated into cholesteryl esters, free cholesterol, triglycerides, and free fatty acids. Cholesteryl esters were distributed throughout the liposomes. Free fatty acids represented a substantial part of cell sap lipids, but were present also in the mitochondria, microsomes, and liposomes. Fatty acids of all fractions were analyzed by gas liquid chromatography. Free fatty acids and cholesteryl ester fatty acids from all cellular fractions were similar in composition and were characterized by considerable quantities of linoleic and arachidonic acid. Triglycerides were characterized by an increased percentage of palmitic and a low content of arachidonic acid. Phosphatidyl choline, phosphatidyl ethanolamine, diphosphatidyl glycerol, and sphingomyelin plus phosphatidyl inositol were isolated from the lipids by preparative thin layer chromatography, and their fatty acids analyzed by gas liquid chromatography. Phosphatidyl choline and phosphatidyl ethanolamine from mitochondria, microsomes, and cell sap were very similar in respect of their fatty acid composition. Sphingomyelin plus phosphatidyl inositol was characterized by a high content of C22:2omega6. Diphosphatidyl glycerol was present in mitochondria and in the cell sap.     

Adulterated butterfat: Fatty acid composition of triglycerides and 2-monoglycerides

Beef tallow and cottonseed oil were mixed with a pure butterfat in the ratios of 2%, 4% and 6% to obtain admixtures of beef tallow with butterfat and cottonseed oil with butterfat. The hydrolysis of individual triglycerides was carried out using the lipase to obtain 2-monoglycerides. The results indicated that butterfat had a higher percentage of C14:0 and C16:0 acids than found in the triglycerides and 2-monoglycerides of beef tallow and cottonseed oil. Beef tallow contained a higher proportion of C18:0 and C18:1 acids than butterfat and cottonseed oil triglycerides or 2-monoglycerides. Cottonseed oil had a higher percentage of C18:2 acid located in triglyceride or 2-monoglyceride than found in butterfat or beef tallow triglycerides and 2-monoglycerides. The analysis of the samples of butterfat containing 2%, 4% and 6% beef tallow revealed that the addition of beef tallow to butterfat affected the fatty acid composition of butterfat triglycerides and 2-monoglycerides with C18:0 and C18:1 acids; the effect was increased with increasing percentages of beef tallow. The addition of cottonseed oil to butterfat in the ratios of 2%, 4% and 6% affected the fatty acid composition of butterfat triglycerides and 2-monoglycerides. It was found that both C18:1 and C18:2 increased as the added cottonseed oil percentages increased.     

Origin of minor constituents of commercial oleic acid

Fatty acids were prepared from beef tallow in the laboratory by alkalization and acidification under a nitrogen atmosphere at temperatures below 100 C. The minor constituents in the beef tallow fatty acids were isolated by the silicic acid method as described previously. They were fractionated by silicic acid liquid column chromatography and characterized by chemical functional group analyses, elemental analyses and infrared spectrophotometric methods. The results suggest that the minor constituents in commercial fatty acids were partly present in the original raw material of beef tallow and were partly formed as artifacts during the manufacturing process. Paper of the Journal Series, New Jersey Agricultural Experiment Station, Cook College, Rutgers, The State University of New Jersey, New Brunswick, NJ 08903.     

Fractionation of Condensed Distillers Solubles and Compositional Characterization of Its Co-Products

Condensed distillers solubles (CDS) was fractionated into a protein-mineral fraction and a glycerol fraction by a chemical method; protein and glycerol-mineral fractions by a physical method; and protein, mineral, and glycerol fractions by a physicochemical method. The co-products from each method, along with CDS, were characterized for concentrations of key constituents (protein, oil, ash, glycerol and other carbohydrates), mineral profile, and amino acid composition. Recovery of mass and main constituents was also investigated. With the chemical method, about two-third of the mass went to the protein-mineral fraction, while by the physical method the equal amounts of mass went to the protein and glycerol-mineral fractions. Protein, minerals, and glycerol were mostly recovered into their respective fractions. CDS and its fractions contained six major minerals (Ca, Mg, P, K, Na, and S) and four trace ones (Cu, Fe, Mn, and Zn). Both chemical and physical treatments caused significant reduction of mineral contents (dry matter basis) in the protein or glycerol fraction. Several amino acids differed significantly in percent relative to total amino acids among fractions but the extent was not substantial for protein-rich fractions. These changes resulting from CDS fractionation are favorable for value added utilization of the new co-products.     

Characterization of expression of a plant oleate desaturase in yeast

We have expressed the oleate desaturase gene of Arabidopsis thaliana in Saccharomyces cerevisiae by means of a galactose-inducible promoter. Transfer of yeast cells to galactose-containing media and growth at 30°C resulted in the production of active oleate desaturase, as shown by the appearance of the diunsaturated octadecadienoic acid (18:2) and hexadecadienoic acid (16:2). The highest level of these two fatty acids was 46.2%. In induced cultures, 18:2 appeared before 16:2, and we show that both of these fatty acids were present first on phosphatidylcholine and then appeared in other phospholipids and a neutral lipid fraction. We raised antibodies against the C-terminal 100 amino acids of oleate desaturase and demonstrated that this protein was in the microsomal fraction of induced cells.     

Characterization of Novel Triacylglycerol Estolides from the Seed Oil of Mallotus philippensis and Trewia nudiflora

Triacylglycerol estolides have been reported as components of the seed oil of a number of plant species and are generally associated with the presence of fatty acids containing hydroxyl groups. We have used MALDI-TOF MS to examine the intact acylglycerol species present in the seed oils of two plants that produce kamlolenic acid (18-hydroxy-Δ9cis,11trans,13trans-octadecatrienoic acid). Mallotus philippensis and Trewia nudiflora were both shown to produce seed oil rich in TAG-estolides. Analysis by MALDI-TOF MS/MS demonstrated that the TAG-estolides had a structure different to that previously proposed after enzymatic digestion of the oil. Acylglycerols containing up to 14 fatty acids were detected but fatty acid estolides were only present in a single position on the glycerol backbone, with predominantly non-hydroxyl fatty acids in the remaining two positions. Increased numbers of fatty acids per glycerol backbone were accounted for by the presence of fatty acid estolides containing a correspondingly greater number of fatty acids. For example, acylglycerols containing seven fatty acids had a fatty acid estolide of five fatty acids at one position on the glycerol backbone. Both capped and uncapped fatty acid estolides, with a free hydroxyl group, were present, with capped fatty acid estolides being more abundant in T. nudiflora and uncapped fatty acid estolides in M. philippensis.     

乌桕梓油脂肪酸组成分析

乌柏是我国四大木本油料之一,种子含油量高,乌桕梓油是由种仁榨取所得的液体油脂,是轻工业、食品和国防等行业的重要油源。乌桕梓油甲酯化后,利用100 m×0.25 mm的GC毛细管柱,气相色谱法测定乌桕梓油的脂肪酸组成。测定结果表明：乌桕梓油中饱和脂肪酸占10.68%,以棕榈酸含量最高,占7.52%。不饱和脂肪酸占89.13%,单不饱和脂肪酸占18.63%,以油酸含量最高,占14.55%;多不饱和脂肪酸占70.50%;其中含量最高的为人体所必需的脂肪酸亚油酸和α-亚麻酸,分别占30.77%和39.30%。还含有相当数量天然植物中少有的奇数碳原子脂肪酸十一烷酸,占0.29%。其中月桂烯酸（占3.19%）和十一烷酸未见报道。     

Lipid Class and Fatty Acid Composition of Psoralia corylifolia Seed

The purified crude lipid of Psoralia corylifolia seeds was subjected to lipid class and fatty acid analysis by thin layer and gas chromatography. The lipid classes identified were triacyl glycerol, free fatty acid, diacyl glycerol, mono acyl glycerol, hydrocarbon-waxester and polar lipid fractions. Most of the fractions were found to contain high level of C_18:1 while C_18:0, C_18:3 and C_20:0 were also found to be present in all the lipid fractions. It has been observed that the diacyl and monoacyl glycerol fractions contain significant amounts of C_14:0 and C_18:0 while the hydrocarbon-waxester fraction was rich in C_22:0. The polar lipids contain high level of C_18:3 and low level of C_18:1 as compared to other lipid fractions. The fatty acid composition of the whole oil was also determined and found to be similar to other fractions. Unidentified long chain fatty acids were also present in significant amounts in all the lipid fractions.     

近临界水中禽类废弃物超低酸水解加工制备氨基酸的工艺优化

为寻求禽类废弃物的有效利用途径,对其进行在近临界水中超低酸水解加工制备氨基酸的工艺优化。用AAA-Direct氨基酸分析仪对水解产物中的氨基酸进行定性和定量分析。以鸡肠为原料,氨基酸总收率为指标,讨论了反应温度、反应时间、硫酸浓度对氨基酸总收率的影响,并通过正交试验确定了鸡肠近临界超低酸水解的较佳工艺条件。实验结果表明,鸡肠水解后可得17种氨基酸。近临界超低酸水解法高效、工艺简单、对环境友好,在较佳的工艺条件下:T=533K,t=28min,H2SO4=0.02%,氨基酸的总收率可达11.49%。     

Analysis oftrans-18:1 isomer content and profile in edible refined beef tallow

Thetrans 18:1 acid content and profile for several samples of edible refined beef tallow were determined monthly over a period of one year. For this purpose, gas-liquid chromatography was combined with silver-ion thin-layer chromatography. The mean content oftrans-18:1 isomers was 4.9±0.9% (n=10) of total fatty acids with a minimum of 3.4% and a maximum of 6.2%. The distribution profile of individual isomers was also established. As in other ruminant fats (milk fat, meat fat), the main isomer is vaccenic (trans-11 18:1) acid. Other isomers, with their ethylenic bonds between positions 6 and 16, were found in lesser amounts. However, some slight but definite differences exist between beef tallow and cow milk fat. The relative proportion of vaccenic acid is higher in the former than in the latter. However, the distribution pattern oftrans-18:1 isomers in beef tallow closely resembles that in beef meat fat (lean part).