Natural skin coating of the apple and its influence on scald in storage: IV.—Oxidation products of α-farnesene

Among the products of aerial oxidation of a-farnesene are carbonyl compounds of lower molecular weight. Several of these have been analysed, as free compounds or derivatives, with the aid of gas chromatography and mass spectrometry. Some of the identified compounds are known to have no effect on scald but three of them, pyruvaldehyde, methyl vinyl ketone and 6-methyl-5-hepten-2-one, require further study.     

Natural skin coating of the apple and its influence on scald in storage III.—α-farnesene

In a study of apple fruits grown under English conditions it was found that at the time of the respiratory climacteric the concentration of α-farnesene in the waxy skin coating began to increase rapidly from a low level and at 12° reached a peak after about 30 days. in the relative amounts of farnesene produced there was little to distinguish the scald-resistant from the scald-sensitive apple variety. Under the various conditions of low-temperature storage in use, it was found that the farnesene content of the skin was most influenced by the nature of the atmosphere, whether air or 8% CO₂, white the farnesene content of the waxy skin coating was more responsive to delay at room temperature before storage, diphenylamine treatment or wrapping in oiled wraps. The results are discussed in relation to the theory that farnesene is a chemical factor in the induction of superficial scald.     

The odour of white bread III. Identification of volatile carbonyl compounds and fatty acids

Summary Carbonyl compounds of white bread, isolated by extraction, were identified as their 2,4-dinitrophenylhydrazones by thin-layer chromatography. Acids were separated from an extract of white bread as their sodium salts, regenerated and analysed by gas chromatography. 24 carbonyl compounds and 13 acids were identified. Of these, 9 carbonyl compounds and 8 acids had not been previously reported to occur in the aroma of white bread.

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Zusammenfassung Carbonylverbindungen von Weißbrot sind — nach Isolierung durch Extraktion — mittels Dünnschichtchromatographie als 2,4-Dinitrophenylhydrazone identifiziert worden. Sduren werden als Natriumsalze von einem Weißbrotextrakt abgetrennt und gaschro matographisch analysiert. 24 Carbonylverbindungen und 13 Säuren wurden identifiziert, wovon 9 Carbonylverbindungen und 8 Säuren in der einschlägigen Literatur noch nicht erwähnt worden sind.

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Die II. Mitteilung erscheint in Heft 5 (Anm. d. Red.)     

The natural occurrence of unusual fatty acids Part 3. Acetylenic fatty acids

Acetylenic compounds especially acetylenic fatty acids (C₁₇ to C₂₁) were first of all identified in higher plants. Their structure is very different with regard to the number of the double and triple bonds per molecule, and the functional groups. The mechanism of the biogenesis and the influencing factors are not definitely clarified. A side pathway of the biogenesis of the saturated fatty acids is supposed. Various physiological effects of the acetylenic fatty acids are presented.     

The natural occurrence of unusual fatty acids. Part 1. Odd numbered fatty acids

A literature review of the natural occurrence and effects of odd numbered fatty acids (C₁₁ to C₃₃) in microorganisms, plants and animals is presented. Not only saturated and unsaturated odd numbered fatty acids but also unsaturated fatty acids with unusual position of double bonds seem to be ubiquitous in small amounts.     

Significant influence of particular unsaturated fatty acids and pH on the volatile compounds in meat-like model systems

The present study aimed to investigate the effects of particular unsaturated fatty acids and pH on volatile compounds in the meat-like model systems containing 21 amino acids and ribose. We have chosen oleic acid (C18:1n-9), linoleic acid (C18:2n-6) and linolenic acid (C18:3n-3) for the present investigation. The effect on the volatile compounds was evaluated at two different pH 5.5 and 6.2. The addition of C18:2n-6 and C18:3n-3 to the Maillard reaction mixtures inhibited the formation of many Maillard compounds or produced in low amount. Whereas, the addition of C18:1n-9 resulted in an increase in the amount of many Maillard compounds. The thiols and thiophenes were preferentially formed at pH 5.5 whereas pyrazines were preferentially favored at pH 6.2. Based on our results, it is suggested that a high level of C18:2n-6 and C18:3n-3 in meat probably causes an undesirable flavor. The pH value of 5.5 was found to be ideal for the formation of volatile compounds associated with desirable flavor of meat.     

The natural occurrence of unusual fatty acids. Part 2. Even numbered fatty acids with unusual position of the double bond

Unsaturated even numbered fatty acids (C₁₀ to C₃₂) with uncommon position of the double bond (not ω-3, 6 or 9) belong to the unusual fatty acids. It seems, that these fatty acids are ubiquitous in small amounts in nature with priority of microorganisms and animal kingdom. Nearly all positions are possible.     

发酵乳中羰基化合物和有机酸含量变化的研究

为考察乳酸菌单菌种发酵乳的产酸特性和产香特性,使用酚试剂分光光度法测定发酵乳中乙醛含量,邻苯二胺法测定发酵乳中的双乙酰含量,并结合滴定酸度法测定发酵乳中的酸度,研究了L.b-3、S.t-9和L.dia菌在不同发酵过程中的乙醛、双乙酰和有机酸含量变化,以此评估乳酸菌单菌种发酵乳中有机酸和羰基化合物的情况。     

Seasonal influences on stratum corneum ceramide 1 fatty acids and the influence of topical essential fatty acids

Ceramide 1 is the main repository of stratum corneum linoleic acid, and changes in the levels of ceramide 1 linoleate are associated with cutaneous abnormalities: essential fatty acid deficiency, atopic dermatitis and acne. We have previously reported seasonal variation in stratum corneum lipids where lipids, particularly ceramides, are very much reduced in winter which probably influences the appearance of skin xerosis in this season. However, investigations into the seasonal variation in ceramide 1 fatty acid levels and the effects of topical essential fatty acids on the composition of these lipid species have not been conducted in healthy subjects. We determined the composition of stratum corneum ceramide 1 esterified fatty acids in leg skin from Caucasian women in winter and summer and also investigated the effects of topical triglycerides rich in linoleic acid on stratum corneum ceramide 1 fatty acid levels in winter. A dramatic seasonal variation was observed. Whereas decreased levels of linoleic acid and some saturated fatty acids (C-15 and C-24) were observed in the winter months, increased levels of oleic acid were found. Nevertheless, it was possible to normalize the levels of stratum corneum ceramide 1 linoleate following topical application of formulations containing linoleic acid-rich triglycerides for 4 weeks. The reduction in ceramide 1 linoleate may lead to impaired stratum corneum function and increased susceptibility to skin xerosis in winter. However, by using formulations containing linoleic acid esters it is possible to correct these changes and possibly improve barrier resilience.     

脂肪酸消毒液对苹果杀菌效果及贮藏品质的影响

本研究采用一种新型脂肪酸消毒液对新鲜富士苹果进行处理,考察了浸泡和喷洒两种处理方式的杀菌效果和对果实整体感官的影响,以及对苹果在常温贮藏条件下品质的影响。杀菌结果表明:相同稀释倍数的脂肪酸消毒液浸泡组杀菌效果优于喷洒组;两种处理方式的500倍和800倍稀释液杀菌时间延长至4 min后,菌落总数无显著性变化;脂肪酸消毒液稀释处理组对苹果味道、颜色的感官评分影响无显著性差异,对气味影响显著,与喷洒组相比,浸泡组对苹果的气味影响较大。贮藏结果表明:脂肪酸消毒液稀释液处理苹果10 min后于20℃条件贮藏40 d,500倍稀释组能有效抑制苹果的呼吸强度、多酚氧化酶(PPO)的活性,延缓失重率、硬度、可滴定酸含量、可溶性固形物含量的下降,显著减少腐烂率,有利于延长苹果的贮藏期并保持苹果固有的风味品质。      

微波对稻谷储藏过程脂肪酶和脂肪酸的影响

为研究微波对稻谷储藏品质的影响,采用2 450 MHz微波处理稻谷,于不同温度(8、20、30℃)下储藏180天,研究储藏过程稻谷脂肪酶活性、游离脂肪酸含量及其组成。结果表明,经低强度的微波条件处理后,稻谷脂肪酶活力和游离脂肪酸的含量均有提高,不饱和脂肪酸含量降低。稻谷储藏过程中,脂肪酶活力逐渐降低,游离脂肪酸含量增加,脂肪酸组成发生变化,低强度微波处理对稻谷的储藏品质影响不大。     

The influence of dietary branched-chain fatty acids on the fatty acid composition of tissue lipids of rats

Branched-chain fatty acids (BCFA) were prepared as a concentrate from the adiposetissue lipids of barley-fed lambs. The BCFA was included in a stock Oxoid ration at levels of 2.5–15% by weight and these diets were given to appetite to female weanling rats for up to 14 days. The influence of the diets on inter alia growth-rate and fatty acid composition of tissue lipids was compared with the effect of the same stock diet with inclusions at a level of 5% by weight of 3-methylhexadecanoic acid (3-MHD), 4-methylhexadecanoic acid (4-MHD), 3,7,11,15-tetramethylhexadecanoic (phytanic) acid and n-hexadecanoic (palmitic) acid which, with the stock ration, served as control. Rats receiving diets containing up to 7.5% BCFA grew almost as well as did those given palmitic acid whereas the animals offered the diets containing 3-MHD, 4-MHD or 10% BCFA barely subsisted. Rats given 10% BCFA or phytanic acid became moribund within 3 days. BCFA accumulated to widely varying degrees in the lipids of the main internal organs. The higher proportions of these acids constituted some 40–60% of the total fatty acids of the lipids of kidney, liver and heart and were associated with diets containing 10% and 15% BCFA and 5% 3-MHD. The lower proportions of the branched acids in the lipids of these organs were in the range 15–25% of the total fatty acids and related to diets that included 2.5% BCFA and 5% 4-MHD. In contrast to the changes in fatty acid composition of the lipids of the main internal organs, those of the central and peripheral nervous systems were only minor, the proportions of branched acids amounting to some 3% in brain tissue and up to 14% in sciatic nerve. Clearance of branched acids from tissue lipids of the main internal organs was almost complete after the animals were returned to the basal diet for 14 days but the loss of branched acids from nerve tissue was evidently less rapid.     

The influence of the dietary polyunsaturated fatty acids on the phagocyte's functional activity in rats

The influence of dietary polyunsaturated fatty acids on the superoxid anion production by peritoneal macrophages and phagocytosis by blood neutrophiles in male Wistar rats weighting 127.0 +/- 3.2 r was investigated after 3 months feeding. Rats fed isocaloric purified diets contained 24% fat representing combinations of lard, sunflower oil and fish oil (eiconol) providing the ratios of w6/w3 fatty acids equal 49.0; 6.1; 1.1. The increasing of superoxide formed by peritoneal macrophages and phagocytic activity of neutrophiles in the group received diet with the minimal ratios of w6/w3 fatty acids compared to that in rats fed diet with ratio 49.0 was noted. The increased activity of mononuclear-phagocytic system was confirmed by morphological investigation of peripheral lymphoid organs.     

The chemical characteristics of apple pectin influence its fermentability in vitro

The aim of the present study was to characterize the fermentability of different apple pectins, as soluble dietary fibres, in vitro. High- and low-methoxyl pectins were fermented completely and very fast by human colonic bacteria, whereas pectic acid and amidated pectin were degraded more slowly. The main fermentation metabolites, i.e. short-chain fatty acids (SCFA) and gases, were produced in lower amounts from pectic acid and amidated pectin. Based on the higher production of SCFA, pectins with a higher degree of methoxylation might be the best candidates for food enrichment due to a beneficial effect on colonic health. On the other hand, the longer persistence of the slowly degraded pectins in the gut may be of advantage as binding and diluting agents for carcinogens.     

Effect of the addition of pancreatic lipase on the ripening of dry-fermented sausages - Part 2. Free fatty acids, short-chain fatty acids, carbonyls and sensory quality

The effect of the addition of nine different amounts (3–500 units) of pancreatic lipase on the composition of free fatty acids (FFA), short-chain fatty acids and carbonyls, as well as the sensory quality, has been studied on dry fermented sausages. The lipase produced a greater release of all fatty acids in relation to the control sausages. The greater the pancreatic lipase content, the higher the release of these fatty acids, the most important ones being myristic, palmitoleic and oleic acids. A lower release of linoleic acid was observed, probably because of its oxidative degradation. At the end of the ripening in all lipase-added batches, a clear increase of the carbonyl content was noticed in relation to conventional sausages. No consistent changes were observed in the short-chain fatty acid fraction. In the sensory evaluation, the highest significant differences (P < 0·01) between control sausages and lipase-added batches were observed when 60 and 90 lipase units were used. According to the chemical and sensory analyses, it can be concluded that the addition of 60 and 90 units to sausages seems to be useful to enhanced the flavour of these products.     

Supplementation of amino acids in apple must for the standardization of volatile compounds in ciders

The aim of this study was to identify the main amino acids responsible for the production of esters in ciders. The experiments were carried out in apple must and synthetic must. The amino acids were analysed by high‐performance liquid chromatography and the volatile compounds by gas chromatography. Aspartate, asparagine and glutamate positively influenced the production of esters in the cider models and were used in the experiments with mixtures. The response surface generated by the proposed model yielded two regions that maximized the production of esters. In addition, the combination of aspartate and glutamate predicted a higher production. The optimal suggested concentrations were 43.4% of aspartate and 56.6% of glutamate for 120 mg/L of total nitrogen. The apple must supplemented with these two amino acids resulted in four times more esters than in the same cider without supplementation, demonstrating the effectiveness of the proposed model.     

Milk fatty acids. I. Variation in the concentration of individual fatty acids in bovine milk

Data from 29 published experiments on Holstein cows, providing 120 dietary treatments, were collated to obtain means, standard deviations, and ranges for the concentrations (mg/g) of 26 major individual fatty acids in bovine milk fat. The influence of diet type (total mixed ration- vs. pasture-based diet) on concentrations of individual fatty acids was examined. Pairwise correlations for concentrations (g/kg) of individual fatty acids in milk showed that almost all of the individual de novo fatty acids were significantly correlated with each other and with the total concentration of de novo fatty acids. Concentrations of individual unsaturated preformed fatty acids were generally positively correlated with each other but were negatively correlated with concentrations of total de novo fatty acids. Substantial variation was found in the concentrations of individual milk fatty acids and, apart from those synthesized de novo, concentrations of individual fatty acids did not vary in concert. The adequacy of literature data for the development of a model to predict the production of the major individual fatty acids in milk is discussed. The limitations associated with the currently available studies that may be used in a predictive model are 1) failure of many publications to adequately describe dietary details, 2) reporting poorly defined milk fatty acids, 3) aggregating a number of closely related fatty acids under a single category, and 4) the selective reporting of only those fatty acids that are present in milk fat in appreciable quantities. Despite these limitations, the data are sufficient to enable development of a model to predict the concentrations and production of major individual fatty acids in milk fat. The extreme variability in concentrations of individual milk fatty acids and the complex matrix of positive and negative correlations among the concentrations of many individual fatty acids suggest that separate equations will be needed to predict the production of each individual milk fatty acid.     

Effect of cold storage on vitamins C and E and fatty acids in human milk

Vitamins C and E and fatty acid levels in human milk were determined when fresh, after refrigeration at 4 °C for 96 h, and after freezing at −20 °C or −80 °C for 12 months. Total vitamin C content at 4 °C (6 h), −20 °C (8 months) and −80 °C (12 months) was significantly decreased. Vitamin E levels did not change at either refrigeration temperature (under 24 h) or at freezing or ultrafreezing temperatures. Our analysis revealed that fatty acids are not affected by cold storage. In conclusion, we recommend a change in milk storage practices; specifically, it should be stored up to 3 h in a refrigerator, up to 5 months in a freezer or up to 8 months in an ultrafreezer (−80 °C). Alternatively, vitamin C supplementation may be considered. In addition, we propose vitamin C as a marker for human milk stability.