Journal of the Science of Food and Agriculture

doi: 10.1002/jsfa.2740080301pmid: N/A

Cookson, M. A.; Ritchie, M. L.; Coppock, J. B. M.

doi: 10.1002/jsfa.2740080302pmid: N/A

Flours recently examined have sometimes shown different characteristics from those previously described. Conflicting results on the breadmaking quality of defatted flours are attributed, from an examination of different flour‐milling products, to differences in the condition of the wheats constituting the grist and to the flour extraction rate, although the latter is not the controlling factor. Several methods of fractionating flour lipids and investigating the baking properties of various fractions are described. Countercurrent distribution of flour lipids is shown to be a useful systematic method of study, some of the tractions having markedly differing effects on bread properties. Further experiments on oxidative flour treatments have indicated that the flour lipid extracted by carbon tetrachloride is little affected by such treatments. The total lipid may, however, be involved in the mechanism of oxidative improvement. Dough and baking tests on undefatted flours and defatted flours in which the extracted lipids have been replaced indicated that the original nature of the flour lipid cannot be fully restored. The ultra‐violet absorption spectra of the lipids from different wheat‐milling products and breads are described and it is shown that such spectra might be used to indicate (a) the bran content of a flour and (b) whether a treated flour has been used in bread production. It is clear from the complicated picture emerging from the results hitherto obtained, that until far more is known of the constitution of flour and the effect of the many factors contributing to its constitution, experimental dough and baking tests remain the best means of assessing flour quality for breadmaking.

Hulme, A. C.; Wooltorton, L. S. C.

doi: 10.1002/jsfa.2740080303pmid: N/A

A study is made by ion‐exchange and chromatography on silica gel of the organic acids present in apple pulp and peel at various stages of maturity. The concentration of quinic acid falls rapidly throughout the developmental period, whilst that of malic acid reaches a peak at 50–60 days after petal fall. Citric acid, present in much smaller proportion than the other two acids, shows considerable changes in amount and concentration.

Burroughs, L. F.

doi: 10.1002/jsfa.2740080304pmid: N/A

The free amino‐acids of apple juices and ciders have been examined by paper chromatography. Asparagine, aspartic and glutamic acids were the principal amino‐acids in most juices, together with small to medium amounts of serine, α‐alanine, γ‐aminobutyric acid, valine, isoleucine, and methylhydroxyproline. Ten other amino‐acids were sometimes present in trace amounts. The amino‐acid content of ciders was extremely small and consisted usually of aspartic and glutamic acids, methylhydroxyproline, an unidentified peptide and traces of several other amino‐acids and possible peptides. Yeast autolysis caused a marked increase in the amino‐acid content of a cider left on its lees. The presence of nucleotide material in juices and cider is indicated.

Bolton, W.

doi: 10.1002/jsfa.2740080305pmid: N/A

The digestibility coefficients for the various carbohydrate fractions in wheat fine middlings, maize germ meal, maize gluten feed, soya‐bean meal and groundnut meal were determined. These fractions included the conventional nitrogen‐free extractives and crude fibre, and also sugar, starch, pentosan, cellulose and lignin. Sugar and starch were completely digested, cellulose and lignin were indigestible whilst the digestibility coefficient of the pentosan varied from 5.6 in maize germ meal to 36·5 in wheat fine middlings.

Call, F.

doi: 10.1002/jsfa.2740080306pmid: N/A

Sorption of ethylene dibromide was studied in the presence of air on twenty different soils at moisture contents corresponding to field capacity. The soils ranged from coarse sands through silts and clays to heavy peats. All isotherms were linear and the sorption coefficient (slope of the isotherm) could be correlated with surface area, with organic matter content, with moisture content and less closely with clay content. The latter three soil properties also correlated with each other. It was found possible to predict the sorption coefficient with reasonable accuracy from moisture content alone.

Call, F.

doi: 10.1002/jsfa.2740080307pmid: N/A

The diffusion of ethylene dibromide vapour through soils of different types has been studied. Both unsteady‐state and steady‐state coefficients agree with theoretical values calculated from known soil properties. Blocked pores are an important factor in the steady state but not in the unsteady state and sorption of vapour on the soil has a great influence on the unsteady‐state coefficient only.

Kieser, Margaret E.; Pollard, A.; Timberlake, C. F.

doi: 10.1002/jsfa.2740080308pmid: N/A

Storage deposits in bottled pasteurized apple juices have been found to consist mainly of degraded juice phenolic compounds, protein material and ash components. The presence of copper in low concentrations promotes sedimentation and leads to the formation of deposits of high copper content: the effect of copper is partly inhibited by the presence of sulphur dioxide. Of the other metals tested only tin was found to increase sedimentation and to appear in significant amounts in the deposits. Studies of juice components in isolated systems suggest that the presence of copper is a main factor in deposit formation and that copper catalyses the degradation of juice phenolic substances, particularly of leucoanthocyanins and epi‐catechin, leading to their precipitation. A comparison is drawn between the storage deposits of apple juices and the non‐biological hazes of beer.

Timberlake, C. F.

doi: 10.1002/jsfa.2740080309pmid: N/A

The interaction of cupric copper with the organic acid, amino‐acid and phenolic components of apple juices has been investigated in juices and model systems. Copper is mainly complexed with malic acid and the dissociation constant of this complex has been calculated; the proportion of copper complexed with amino‐acids is small. Copper forms soluble complexes with the phenolics at the pH of juices, with reduction of cupric copper to the cuprous state and leading to the precipitation of copper and partly degraded phenolics. The significance of these findings is discussed in relation to the storage behaviour of apple juices.

Ames, W. M.

doi: 10.1002/jsfa.2740080310pmid: N/A

Gelatin has been prepared from the same precursor by three methods. Energetic acid pretreatment results in gelatin of the same isoelectric point as does energetic alkaline treatment. Irregularities in the nitrogen content of collagen and gelatin can be explained by the presence of non‐nitrogenous impurity. Substances associated with collagen in small quantity may be the most important factor in the transformation of collagen to gelatin.