Showing papers in "Journal of the Science of Food and Agriculture in 1968"
TL;DR: In this article, a method was devised in which the specific hydrolysis of starch completely to glucose is achieved by means of an amyloglucosidase, and the contents of α-linked glucose polymers in a number of biological samples were determined.
Abstract: A review of methods available for the determination of starch suggested, for reasons given, that none was satisfactory for the determination of α-linked glucose polymers in biological materials. Therefore, a method was devised in which the specific hydrolysis of starch completely to glucose is achieved by means of an amyloglucosidase. Glucose is estimated using glucose oxidase. Contents of α-linked glucose polymers in a number of biological samples were determined, and compared with those obtained using 0.36 N-H2SO4 to effect hydrolysis.
396 citations
TL;DR: The volatile compounds stripped from boar, hog and gilt fats under conditions of high vacuum and elevated temperature have been subjected to gas chromatographic and olfactory analysis as mentioned in this paper.
Abstract: The volatile compounds stripped from boar, hog and gilt fats under conditions of high vacuum and elevated temperature have been subjected to gas chromatographic and olfactory analysis. The compound primarily responsible for the taint of boar fat has been isolated and identified by mass spectrometry as 5α-androst-16-ene-3-one. It has an unpleasant odour of perspiration and is detectable in most boars of 200 lb live-weight and over but not in hogs or gilts.
365 citations
TL;DR: In this article, a method was developed for the study of starch retrogradation by differential thermal analysis using the expression θ8 = exp (-ktn), where θ = the fraction of crystallisable starch remaining uncrystallised at time t. The results indicated that the nucleation process in starch crystallisation is instantaneous in the systems studied.
Abstract: A method was developed for the study of starch retrogradation by differential thermal analysis. The kinetics of the crystallisation process were studied using the expression θ8 = exp (-ktn), where θ = the fraction of crystallisable starch remaining uncrystallised at time t. The values for the Avrami exponent (n) and the rate constant (k) were found to coincide with values previously obtained for the staling of bread, as followed by measurement of crumb elastic modulus. No difference between the time constants of gels cooled slowly and rapidly after gelatinisation was found, indicating that the nucleation process in starch crystallisation is instantaneous in the systems studied. The fact that the Avrami exponent is unity also suggests that the nucleation process is instantaneous, and that it is followed by rod-like growth of crystals.
154 citations
TL;DR: In this paper, the relationship between loaf specific volume and the rate and extent of staling in bread as measured by changes in crumb elastic modulus have been examined, and it was shown that the effect of changes in bread specific volume on staling characteristics is greater in bread prepared by bulk fermentation than in bread made by the Chorleywood Bread Process.
Abstract: The quantitative relationships between loaf specific volume and the rate and extent of staling in bread as measured by changes in crumb elastic modulus have been examined. The results show that loaf specific volume is a major factor in determining both the rate and extent of staling, both of which decrease in a linear manner, over the range studied, as loaf volume increases. Only two factors have been found that have a significant influence on these curves, the basic breadmaking process and the storage temperature. The influence of changes in loaf specific volume on staling characteristics is greater in bread prepared by bulk fermentation than in bread prepared by the Chorleywood Bread Process. Bread made by the Chorleywood Bread Process stales less rapidly than bread made by the conventional bulk fermentation process. The effect of loaf specific volume on the rate of staling is more marked as the storage temperature is lowered.
110 citations
TL;DR: During storage of apples at 1° the concentration of a-farnesene in the ‘coating’ and adjacent cells increased to a maximum and then declined and at the highest maximum farnesene was 15% of the total lipid of the coating.
Abstract: During storage of apples at 1° the concentration of a-farnesene in the ‘coating’ (mainly cuticle) and adjacent cells increased to a maximum and then declined. At the highest maximum farnesene was 15% of the total lipid of the coating. Evidence is presented for a role of a-farnesene in superficial scald. More a-farnesene was found in earlier picked apples and more in the scald-liable Granny Smith than in the scald-resistant Crofton variety. During storage a-farnesene moved from the fruit to the oiled wraps until wraps contained more than twice as much as the fruit. Diphenylamine reduced the production of a-farnesene in later picked apples.
97 citations
TL;DR: In this article, various methods for assessing the extent that the protein has spoiled in stored beef are considered in relation to the various criteria discussed in Part I. From the point of view of routine quality control, the macro-distillation of the volatile nitrogen produced appears to be the most reliable method.
Abstract: Various methods for assessing the extent that the protein has spoiled in stored beef are considered in relation to the various criteria discussed in Part I. From the point of view of routine quality control, the macro-distillation of the volatile nitrogen produced appears to be the most reliable method. From statistical correlations with odour scores, most beef can be considered to be acceptable if the total volatile nitrogen (TVN) and TVN/FF (fat-free) figures do not exceed 16.5 and 19.7 mg N/100 g respectively.
96 citations
TL;DR: The salivary glands of boars, hogs and gilts were examined for the presence of sex odour in this paper, and a musk-smelling compound was identified as 3α-hydroxy-5α-androst-16-ene.
Abstract: The salivary glands of boars, hogs and gilts have been examined for the presence of sex odour. The submaxillary salivary glands of all boars examined possessed a musk-smelling compound, which was absent from the glands of the hogs and gilts. The compound, which has been isolated and identified as 3α-hydroxy-5α-androst-16-ene, is closely related to 5α-androst-16-ene-3-one, previously isolated from boar fat.
91 citations
TL;DR: The amount of ‘glucose’ extracted from soil by barium hydroxide increased during air-drying, but once air-dry no further change occurred, even on prolonged storage, and was proposed as an index of potentially available N in soil.
Abstract: Previous work on the distribution of radioactivity in the organic matter of soils incubated with 14C labelled ryegrass suggested that the amount of organic matter extracted by barium hydroxide might serve as an index of potentially available N in soil. This suggestion was tested on a set of soils for which the amounts of N mineralised during incubation, and the amounts of N taken up by ryegrass grown in the soils, were known. The amounts of organic C and non-nitrate N extracted by barium hydroxide were correlated fairly closely with the amounts of N released by the soils; polysaccharide (measured as the glucose equivalent) extracted by barium hydroxide was more closely correlated with release of N. The amount of ‘glucose’ extracted was significantly correlated with the yield of unfertilised barley in 36 field experiments (r = 0.83**); the correlation with response of barley to N was smaller (r = −0.54**).
The amount of ‘glucose’ extracted from soil by barium hydroxide increased during air-drying, but once air-dry no further change occurred, even on prolonged storage.
Barium hydroxide-extractable ‘glucose’ is proposed as an index of potentially available N in soil. The correlation coefficients between uptake of N by ryegrass grown in pots (14 soils) and soil measurements were 0.70**, 0.65**, 0.70**, 0.67**, and 0.28, respectively, for barium hydroxide-extractable ‘glucose’, N extractable by boiling water, or sodium bicarbonate, ammonia released by hot aqueous calcium hydroxide, and ammonia released by alkaline permanganate. None of the chemical tests were correlated as closely with uptake of N by grass, as the N mineralised when the re-wetted air-dried soil was incubated.
82 citations
TL;DR: Seed meals of winter and summer types of varieties of Brassica napus and B. campestris, grown at different localities and in different years, have been analysed for content of glucosinolates which produce oxazolidinethiones and volatile isothiocyanates upon enzymic hydrolysis.
Abstract: Seed meals of winter and summer types of varieties of Brassica napus and B. campestris, grown at different localities and in different years, have been analysed for content of glucosinolates which produce oxazolidinethiones and volatile isothiocyanates upon enzymic hydrolysis. Considerable differences existed in amounts of glucosinolates between species and between winter and summer types of the same species. Varietal differences were relatively small in most of the material studied. Samples of the Polish summer rape variety Bronowski and selections from this variety, however, exhibited very low glucosinolate contents; this is probably genetically determined.
Environmental variation generally amounted to ±15% of the average value. Under certain environments, however, 65% lower values than average were obtained.
Lack of sulphur in the growth medium of soil-free cultures resulted in seeds low in glucosinolates. In practical farming low glucosinolate content has been found in rape seed as a result of low sulphate content in the soil.
80 citations
TL;DR: It is suggested that because of the rapid lowering of the viscosity of its solutions by reducing agents the major, important fraction of glutenin consists of linear molecules made up of polypeptide chains linked to one another difunctionally by S.S bonds.
Abstract: It is suggested that because of the rapid lowering of the viscosity of its solutions by reducing agents the major, important fraction of glutenin consists of linear molecules made up of polypeptide chains linked to one another difunctionally by S.S bonds. When dough is stretched the natural tendency of the polypeptide chains to return to a contracted state of low free energy accounts for the elasticity. The interchain S.S bonds are essential for elasticity because inter-chain adhesion between individual polypeptide chains will not overcome the stronger intra-chain forces unless reinforced by the S.S bond. If extension exceeds the elastic limit, viscous flow occurs because steric hindrance and molecular slip will prevent a return to the original conformation. Disulphide interchange is believed to play an important part in stress relaxation. Mechanical scission of S.S probably occurs when molecules at their elastic limit are subjected to too much stress; this may explain the work maximum in the Chorleywood Bread Process. Explanations are advanced for mechanical and activated dough development and evidence in favour of the hypothesis is discussed.
78 citations
TL;DR: In this paper, two experiments were carried out; in the first, wilted Italian ryegrass at two different dry matter (DM) levels (34% and 47%) was ensiled, in the second, fresh grass (15.9% DM) and similar herbage wilted to 30.3% DM were ensiled.
Abstract: Two experiments were carried out; in the first, wilted Italian ryegrass at two different dry matter (DM) levels (34% and 47%) was ensiled; in the second, fresh grass (15.9% DM) and similar herbage wilted to 30.3% DM were ensiled. Total edible DM losses from the wilted silages were low and ranged from 6.7 to 10.4%. Changes in individual sugars and organic acids were followed. The residual amounts of sugars in the wilted silages were directly related to the degree of wilting. All silages were well preserved, but little fermentation had occurred in the material wilted to 47 % DM. From a knowledge of the sugars lost and amounts of mannitol and ethanol formed it has been possible to examine quantitatively the main chemical changes during the ensilage of the wilted materials. The results confirm the efficiency with which wilted grass is anaerobically conserved.
TL;DR: In this paper, chlorogenic and quinic acids were isolated from the kernel of sunflower seed by column chromatography and identified by paper chromatography, respectively, and the contents of both acids in the kernel and hull of the sunflower seeds were determined and the conversion of chlorogenic acid into quinic acid at temperatures of 100° and 135° was followed.
Abstract: Chlorogenic and quinic acids were isolated from the kernel of sunflower seed by column chromatography and identified by paper chromatography. Ultra-violet and infra-red spectra of the above acids were compared with those of pure preparations. The contents of both acids in the kernel and hull of sunflower seeds were determined and the conversion of chlorogenic acid into quinic acid at temperatures of 100° and 135° was followed. During storage of sunflower meal re-synthesis of chlorogenic acid was observed. Effects of isolates of chlorogenic and quinic acids on α-amylase, trypsin and lipase activity were detected.
TL;DR: In this article, the authors extract six compounds which are more strongly adsorbed on to silicic acid than those previously described, and one of these compounds has been isolated by column chromatography.
Abstract: Of the antioxidants extracted from oats, 36% (by weight) consists of six compounds which are more strongly adsorbed on to silicic acid than those previously described, 1,2 One of these has been isolated by column chromatography. On hydrolysis it yields caffeic acid (2 moles), ferulic acid (1 mole), glycerol (1 mole) and long-chain ω-hydroxyacid (1 mole). The ω-hydroxyacid fraction contains the homologues, C22 (5%), C26 (64%), and C28 (31%).
The probable structures of the compounds are discussed.
TL;DR: In this article, a review of the role of food spoilage in industrial control is presented, with suggestions for a coordinated program of study which could help in clarifying some of the difficulties inherent in the application of meat spoilage research.
Abstract: Numerous chemical and physical tests have been described which reflect the biochemical and other changes which occur in meat during storage. Although some work has occasionally included the correlation with organoleptic data, there have been few suggestions as to possible critical legal or control limits. In industrial control, however, each method has to be considered in relation to the purpose intended and semi-empirical tests may be of value provided that the procedure is standardised. Critical maxima based on chemical values have been recommended for white fish, which differs, however, from meat in having a negligible fat content. With meat, protein breakdown usually precedes fat spoilage, but in certain circumstances the order of these reactions is reversed. Recommended limits for meat should take into account both types of spoilage. The review concludes with suggestions for a coordinated programme of study which could help in clarifying some of the difficulties inherent in the application of meat spoilage research in industrial control.
TL;DR: Some of the characteristics of a melon seed oil, which is shown to be of the semi-drying type containing mainly linoleic and oleic acids, are described in this article.
Abstract: Some of the characteristics of a melon seed oil, which is shown to be of the semi-drying type containing mainly linoleic and oleic acids, are described.
TL;DR: The results confirm that low average Ca concentration is associated with bitter pit and it is suggested that if theaverage Ca concentration exceeds 5 mg/100 g fresh weight the sample will probably be free from this disorder.
Abstract: There is evidence that the incidence of each of three storage disorders of Cox's Orange Pippin apples (senescent breakdown, low-temperature breakdown and bitter pit) is affected by the mineral composition of the fruit. These effects have been studied by comparing initial average compositions of bulk samples with the storage behaviour of bulk replicates and by experiments with individual apples in which apples were analysed after their storage record was known.
It is suggested that if the Ca level in an apple is less than 3 mg/100 g fresh weight it will be liable to senescent breakdown at an early stage of storage. A P concentration of less than 8 mg/100 g may have the same result even if the Ca level is high.
Low-temperature breakdown is less likely in apples with high levels of K, P and Mg than in apples with low levels of these elements.
The results confirm that low average Ca concentration is associated with bitter pit. It is suggested that if the average Ca concentration exceeds 5 mg/100 g fresh weight the sample will probably be free from this disorder. The relationship between Ca and bitter pit in apples stored individually was not clearly defined.
TL;DR: In this paper, a method for the estimation of individual polyphenols of tea leaf was described, where two-way paper chromatography of a methanolic extract of the material were located under ultra-violet light.
Abstract: A method is described for the estimation of individual polyphenols of tea leaf. Polyphenols separated by two-way paper chromatography of a methanolic extract of the material were located under ultra-violet light. The excised spots were eluted with water and estimated from extinctions at 275 nm. Three of the polyphenols, (−)-epigallocatechin gallate, (−)-epigallocatechin and (−)-epicatechin gallate, which comprise 10-19% of the dry matter of tea shoots from Assam, are partly consumed during the manufacture of black tea. Seasonal variation in the polyphenolic content of some jats and clones grown in North East India are described. The phenolic content of the tea shoots was higher during rains. Changes in the phenolic pattern during the growth and development of tea flower, fruit and seed are described. Organs of tea, such as sepals, petals and pericarp with closer morphological affinities to the leaf, showed a greater degree of similarity in their phenolic pattern compared with other organs such as stigma, style, carpel, anther and testa. The gallates were mostly confined to the chlorophyll-bearing organs.
TL;DR: In this article, a simple but effective sampling technique was used to collect the flavour volatiles of cooking cabbage using gas chromatography 35 components were obtained and most of these were identified using relative retention data and mass spectrum evidence.
Abstract: A simple but effective sampling technique was used to collect the flavour volatiles of cooking cabbage. Using gas chromatography 35 components were obtained and most of these were identified using relative retention data and mass spectrum evidence. The relative abundance of each volatile was calculated.
TL;DR: The amount of calcium in mature apples appears to be related to certain storage disorders as mentioned in this paper, such as bitter pit, which occurs in the first few weeks of its development. But the factors affecting the movement of calcium into or out of apples are not known, but the limited evidence available suggests that movement of calcification may occur during periods of abnormally dry weather.
Abstract: The amount of calcium in mature apples appears to be related to certain storage disorders. For Cox's Orange Pippin a difference of 2 mg in a total calcium content per fruit of about 5 mg can make the difference between good and bad keeping.
Most of the calcium moves into the fruit during the first few weeks of its development (approximating to the period during which the cell walls are being formed). Thereafter (during the period of cell expansion) the movement of calcium is no longer in one direction only, and as much as 1 mg may move out of the fruit. This may be of the same order of magnitude as that contributed by calcium sprays, which are now commonly applied to improve storage quality.
The factors affecting the movement of calcium into or out of apples are not known, but the limited evidence available suggests that movement of calcium out of the fruit may occur during periods of abnormally dry weather. These are the conditions which are usually associated with the occurrence of bitter pit.
TL;DR: From statistical correlations with odour scores, most meats were considered acceptable provided the FFA did not exceed 1.2% (calculated as oleic acid on the extracted fat), and several of the other fat spoilage methods considered gave values which rose during the storage period to a maximum and then either remained constant or decreased steadily to a very low figure.
Abstract: Various methods for assessing the extent to which the fat has deteriorated in stored beef are considered in relation to various criteria discussed in Part I. From the point of view of routine quality control, the titrimetric determination of free fatty acids (FFA) appears to be the most reliable method. From statistical correlations with odour scores, most meats were considered acceptable provided the FFA did not exceed 1.2% (calculated as oleic acid on the extracted fat). Several of the other fat spoilage methods considered gave values which rose during the storage period to a maximum and then either remained constant or decreased steadily to a very low figure. Most fresh samples gave peroxide values of 0.1-1.0 mequiv./kg (on the extracted fat), but a critical limit of 5 might be applied under practical conditions.
TL;DR: In this article, a method for determining the "creaming power" of black tea is proposed, and the effects of caffeine, theaflavin and thearubigin content, also the composition of the the arubigins (as indicated by the E380/E460 value) of the black tea, the strength of infusion and the pH of the infusing water on the amount of cream formed in infusions were investigated.
Abstract: Tea ‘cream’ is a finely-divided suspension of insoluble particles that forms when a strong infusion of black tea cools. This study not only confirms that the principal constituents of ‘cream’ are theaflavins, thearubigins and caffeine, but shows that ‘cream’ also contains smaller amounts of other flavonoids, non-caffeine nitrogen compounds, chlorophyll, and inorganic material; all of which are present in the original black tea. The effects of caffeine, theaflavin and thearubigin content, also the composition of the thearubigins (as indicated by the E380/E460 value) of black tea, the strength of infusion, and the pH of the infusing water on the amount of cream formed in infusions were investigated. Evidence was obtained that creaming causes a partial fractionation of the thearubigins. A method for determining the ‘creaming power’ of tea is proposed.
TL;DR: A preparation similar to the crude ‘lipoprotein’ precursor of purothionin previously reported in the literature and stated to contain ‘lecithin’ on the basis of the presence of lipid phosphorus has been partially resolved into six components.
Abstract: Purothionin, an unusual wheat protein and the ‘fast-moving wheat globulins’ have been separated into two components. Earlier evidence of the close similarity of purothionin and these ‘globulins’ is strengthened by amino acid analyses, ‘fingerprints’ (peptide mapping) and C-terminal end group determination of the individual components. A preparation similar to the crude ‘lipoprotein’ precursor of purothionin previously reported in the literature and stated to contain ‘lecithin’ on the basis of the presence of lipid phosphorus has been partially resolved into six components, and the presence of phosphatidyl choline, amino phospholipids and two glycolipids has been demonstrated in fractions containing purothionin.
TL;DR: Low levels of calcium were found to be associated with many of the disorders, and high concentrations of other elements appeared to be a contributory factor in rendering apples liable to particular disorders as mentioned in this paper.
Abstract: In 1967, when an unusual number of disorders were present in apples grown in England, Cox's Orange Pippin apples with disorders at the time of picking or after storage were obtained from various sources and analysed for mineral constituents. The results were compared with those for sound apples, from similar or different samples.
Low levels of calcium were found to be associated with many of the disorders. At these low levels of calcium, high concentrations of other elements appeared to be a contributory factor in rendering apples liable to particular disorders.
TL;DR: The influence of various yeasts on the growth of lactic acid bacteria in wine was tested by inoculating Lactobacillus hilgardii, L. brevis and two strains of Leuconostoc mesenteroides into experimental wines made with twelve different yeasts of the genus Saccharomyces.
Abstract: The influence of various yeasts on the growth of lactic acid bacteria in wine was tested by inoculating Lactobacillus hilgardii, L. brevis and two strains of Leuconostoc mesenteroides into experimental wines made with twelve different yeasts of the genus Saccharomyces. Wines made from juice which had been infected with several spoilage yeasts and then fermented with a wine yeast were also tested in this way. It was found that the yeasts differed considerably in their effects on bacterial growth. In some of the experimental wines bacterial growth was delayed or failed altogether. Generally, the unfavourable influence of any yeast on bacterial growth was much reduced if the wines were left in contact with the yeast cells for some weeks after the fermentation.
The significance of these results in relation to the occurrence of malo-lactic fermentation in commercial wineries is discussed.
TL;DR: A proportion of the wheat samples tested for α-amylase activity by the Hagberg penetrometer method during the 1961 New Zealand harvest gave higher results on flours than on wheatmeals milled from the same wheats as discussed by the authors.
Abstract: A proportion of the wheat samples tested for α-amylase activity by the Hagberg penetrometer method during the 1961 New Zealand harvest gave higher results on flours than on wheatmeals milled from the same wheats. This effect is due to the lower level of calcium available as enzyme cofactor in the meals, caused by combination with phytic acid. Because of this effect and because the internal distribution of α-amylase in wheat grains is variable, testing for sprout damage in milling wheat is best carried out on flours rather than wheatmeals.
TL;DR: In this article, the principal ionic constituents of soil solutions were determined by a liquid displacement technique and increases in ionic concentration of the soil solution were observed over a period of 53 days and were due almost entirely to calcium.
Abstract: Soil solutions were obtained by a liquid displacement technique and their principal ionic constituents were determined. Increases in ionic concentration of the soil solution were observed over a period of 53 days and were due almost entirely to calcium. magnesium and nitrate ions. These increases are assumed to be caused by nitrification.
TL;DR: The amino acid composition of twenty-six food items common in the Middle East has been determined by ion-exchange chromatography and the protein quality scores have been calculated by two methods and are reported together with the E/T ratios.
Abstract: The amino acid composition of twenty-six food items common in the Middle East has been determined by ion-exchange chromatography. A pre-oxidation procedure was used for the determination of cystine but was not found satisfactory for the determination of methionine. In addition to the amino acid composition the protein quality scores have been calculated by two methods and are reported together with the E/T ratios (the total essential amino acids per total nitrogen).
TL;DR: In this article, a method has been developed for the quantitative determination of p-hydroxybenzyl isothiocyanate in enzymic digests of seed meal of white mustard (Sinapis alba L.).
Abstract: A method has been developed for the quantitative determination of p-hydroxybenzyl isothiocyanate in enzymic digests of seed meal of white mustard (Sinapis alba L.). The isothiocyanate was treated with sodium hydroxide and the released thiocyanate was determined by use of ferric nitrate reagent. A sample in which the ferric thiocyanate complex was destroyed by addition of mercuric chloride was used as a control for the colorimetric determinations. The yields of isothiocyanate obtained after hydrolysis of p-hydroxybenzylglucosinolate at different pH have been studied. A relative standard deviation of 0.9% was found when the method was applied to micro- quantitities. The simplicity and rapidity of the method and its applicability to small samples make it well suited for use in connexion with plant breeding.
TL;DR: The greatest weight loss was observed with component items of high molecular weight such as meats and fish, and Calcium pectate membranes gave the best results.
Abstract: Preliminary studies have shown that pieces of fruit, meat, fish, and whole shellfish can be dehydrated osmotically. Fifty percent invert sucrose was used as a solute; edible semipermeable membranes maintained osmotic differential and reduced solute contamination of the product. The greatest weight loss was observed with component items of high molecular weight such as meats and fish. Some of the products when re-hydrated show a marked similarity to the fresh food. Calcium pectate membranes gave the best results.
TL;DR: In this article, six species of earthworms from an arable soil were analysed for residues of aldrin, dieldrin, DDT and γ-BHC.
Abstract: Six species of earthworms from an arable soil were analysed for residues of aldrin, dieldrin, DDT and γ-BHC. The ratios between the concentrations of γ-BHC, aldrin + dieldrin and p,p′-DDT + p,p′-DDE in the earthworms and in the soil (concentration factors) were similar but the residue concentrations were consistently higher in the smaller more shallow-living species Allolobophora caliginosa, A. chlorotica and A. rosea than in the larger deeper-living species Lumbricus terrestris, A. longa and Octolasion cyaneum.
In arable field plots, dieldrin residues in A. longa and A. chlorotica increased with increasing concentrations in the soil but the concentration factors decreased. The concentrations of residues in earthworms (W) appear to be related to those in the soil (S) by an equation of the form W = aSb where a and b are constants, the latter being about 0.79 for a wide range of residue data embracing the uptake of aldrin-dieldrin, DDT components, and γ-BHC by earthworms.