摘要:

AbstractThe growth of the California wine industry since Prohibition derives from a sound technical base and a deliberate attempt to improve quality.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740470302

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe bean weevil Acanthoscelides obtectus (Say) is a major storage peat ofPhaseolus vulgarisL (kidney, haricot bean). The seeds ofP vulgariscontain high levels (up to 30 mg g−1DM) of lectin, which has been shown to be toxic towards larvae of the related bruchid storage pest of cowpea,Callosobruchus maculatusF. The lack of toxicity of this lectin towards larvae ofA obtectusis demonstrated. Unlike the strong binding of lectin to the midgut epithelium observed in larvae ofC maculatus, no binding of lectin molecules was found to occur in the gut epithelial cells ofA obtectus. This observation provides the basis for a hypothesis explaining the lack of toxicity ofP vulgarislectin towardsA obtectus. Assays of proteolytic activity in gut homogenates ofC maculatusandA obtectussuggest that the difference in susceptibility of the two insects towards the toxic effects of the lectin is not due to differential inactivation by proteolysis. Besides its effects on larval development, the lectin has a further effect at pupation, causing disruption of adipose tissues inC maculatusbut having no effect onA obtectu

ISSN:0022-5142    

DOI:10.1002/jsfa.2740470303

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe true ileal digestibility of nitrogen was determined in 20 meat and bone meal samples using 120 growing rats. Correction for endogenous ileal nitrogen excretion was based on feeding a further 15 rats a protein‐free diet. The in‐vivo digestibility estimates were compared with in‐vitro values determined using either a multi‐enzyme digestibility assay (method A), the pronase assay (method B) or a multi‐enzyme digestion, pH‐drop assay (method C). The in‐vivo true digestibilities of lysine for 12 of the meat and bone meal samples were compared with fluoro‐dinitrobenzene (FDNB) available lysine values.The mean in‐vivo digestibility values ranged from 57.2 to 79.1 % and the mean coefficient of variation between rats within meals was 7.6%. For methods A and B the correlations between in‐vitro and in‐vivo digestibility were low and not significant (P>0.05). There was a significant positive correlation between pH at 10 min from the start of in‐vitro digestion and in‐vivo digestibility (r= +0.75; P<0.001) as was the case for pH at 20 min (r= +0.52; P<0.05). The positive relationship between pH at 10 or 20 min and in‐vivo digestibility was contrary to expectation and may have been caused by the potentially high buffering capacity of meat and bone meal. The in‐vitro methods A, B and C each showed a high degree of precision.The mean in‐vivo true ileal digestibility of lysine in the meat and bone meals ranged from 64.7 to 86.9 %. There was no significant correlation between in‐vivo lysine digestibility and FDNB available lysine. There appeared to be an interaction between FDNB lysine availability and true ileal lysine digestibility, such that the meals with lower in‐vivo digestibility had availability values higher than the corresp

ISSN:0022-5142    

DOI:10.1002/jsfa.2740470304

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractVariations in amino acid content of fish meals can be due to differences between meals or to analytical shortcomings. The purpose of the cooperative study reported here was to compare the accuracy of the ion‐exchange (IE) and gas Chromatographic (GC) methods when applied to fish meal. The between‐laboratory and within‐laboratory variations were determined by analysing hidden duplicates of eight meals in four laboratories using IE and in a further three laboratories using GC.The work exposed certain pitfalls and inconsistencies in replicating results. A major source of variation in the IE method was identified as the instability of the ninhydrin reagent leading to the consequent variation in the colour yield of some amino acids which was not compensated by the use of norleucine as an internal standard. Significant between‐laboratory variations and fish meal × laboratory interactions for certain amino acids existed. The work confirmed a need for replicate analysis of samples, whether done by IE or GC.Without discarding any outlying values, coefficients of variation for repeatability (Within‐laboratory variation) varied from 3.5 to 9.7% for IE and 3.5 to 8.4% (histidine at 20%) for GC. coefficients of variation for reproducibility (between‐laboratory variation) varied from 4.1 to 14.4% for IE and 4.5 to 11.9% (20% for histidine) for GC. The values for lysine reproducibility were 10.8% and 4.8% and for methionine wee 13.6% and 8.2% respectively for IE and GC.Neither of the methods was clearly superior for determining the amino acid content of fish meals. It would appear, however, that the GC method tended to result in lower within‐laboratory variance, with arginine and histidine as exceptions.An amino acid mixture, a centrally prepared hydrolysate and a protein of known composition wer

ISSN:0022-5142    

DOI:10.1002/jsfa.2740470305

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe specificity of rabbit anti‐native ovalbumin antibodies against native ovalbumin (NOA) or heat‐denatured ovalbumin (HDOA) was studied by affinity chromatography, ELISA techniques, quantitative immuno‐precipitation and HPLC. Affinity‐purified antibodies were prepared either by passing antisera successively on an NOA column and an HDOA column, or vice versa. Antisera were found to contain about 85 % of antibodies directed against NOA, 7% specific for HDOA and 8% retained by both columns.It is shown that antibodies specific for NOA fully precipitated NOA in liquid‐phase precipitation but were unable to bind NOA in ELISA using NOA‐coated plates, while recognising NOA trapped on the solid phase by a first layer of antibodies: ovalbumin was thus completely denatured during interaction with plastic as shown also by the fact that antibodies specific for HDOA reacted with NOA‐coated plates.These results point out the need to modify ELISA tests for monoclonal antibodies selection and for structural studies of food molecules in complex mixtures. However, this observation, which holds true for ovalbumin, might not apply to

ISSN:0022-5142    

DOI:10.1002/jsfa.2740470306

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractAn automated, rapid and much simplified XRF procedure for assessing total sulphur in graminaceous plant materials is described. Sample preparation has been refined and microprocessor control incorporated to provide considerable savings in analytical time.The procedure has been tested using samples from two grass‐silage cuts, taken from an ADAS (Agricultural Development and Advisory Service) trial studying responses, under intensive grassland management, to sulphur and nitrogen applications. Good correlation between XRF and wet chemical analysis was achieved, and sample turnround was markedly increased. The method produced accurate results for both cuts with high precision and reproducibility where careful attention was paid to sample homogeneity and disc preparation. The potential for wider application of XRF techniques to elemental analysis of agricultural materials is discusse

ISSN:0022-5142    

DOI:10.1002/jsfa.2740470307

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe flavonoid compounds present in almond (Prunus amygdalus, Rosaceae), Jara (Cistus sp Cistaceae),Echiumsp (Boraginaceae) andChrysanthemumsp (Compositae) bee pollens have been studied by TLC, 2D PC and HPLC techniques. These bee pollens show characteristic flavonoid patterns which allow their use as biochemical markers of their plant origin. In addition, the flavonoid patterns of natural almond and ‚Jara’︁ pollens have been shown to be identical to those of the corresponding bee pollens confirming their use as chemical markers. The flavonoid aglycones obtained by acid hydrolysis of pollen flavonoids are also useful for identification purposes. Almond bee pollen contains 8‐methoxykaempferol, kaempferol and quercetin 3‐glycosides, ‚Jara’︁ bee pollen produces quercetin and isorhamnetin 3‐glycosides and trace amounts of myricetin and kaempferol 3‐glycosides,Echiumbee pollen contains mostly kaempferol 3‐glycosides and traces of quercetin 3‐glycosides, andChrysanthemumcontains kaempferol, apigenin, and quercetin 3‐glycosides. The major compound in almond pollen, namely 8‐methoxykaempferol 3‐glycoside, was not detected in the related apple,

ISSN:0022-5142    

DOI:10.1002/jsfa.2740470308

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe aim of the present study was to find a method alternative to enzymic hydrolysis for the analysis of grape terpenyl glycosides. GC after trimethylsilane derivatisation, and HPLC on four different stationary phases, ie bare silica, aminopropyl‐, diol‐ and octadecyl‐bonded silicas, were in turn considered for the separation of these aroma precursors extracted from grape juice, and specific enzymic hydrolyses with highly purified glycosidases showed which were the major components. These investigations show that reversed‐phase liquid chromatography is better suited for both the direct and individual analysis of these gly

ISSN:0022-5142    

DOI:10.1002/jsfa.2740470309

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractPhytic acid content of eight different types of leavened and unleavened flat breads was determined. It was highest in unleavened and non‐fermented whole wheat chapati and lowest in the leavened and fermented white wheat flat bread roghni nan. The effect of baking conditions, bread composition and phytic acid content on in‐vitro digestibility of protein was measured using a pepsin multienzyme pH stat technique. The amino acids released were separated by ultrafiltration.The rate of protein digestibility of flat bread and amino acid released depended upon the type of flour used, baking conditions, phytic acid content and other antiproteolytic constituents of breads.Leavening and fermentation of breads resulted in an increase of protein digestibility and availability of amino acids. Addition of soya flour increases the protein digestibility of breads whereas millet flour decreases

ISSN:0022-5142    

DOI:10.1002/jsfa.2740470310

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe results are reported of single‐blind, medically supervised studies in volunteers of the association between the histamine content of mackerel and the incidence of scombrotoxicosis. Volunteers consumed 25 or 50 g of fresh or spoiled mackerel containing varying quantities of endogenous or added histamine. In one study the ability of HI and H2 histamine antagonists to modify symptoms was investigated. Objective parameters (pulse rate, skin temperature and peak expiratory flow rate) were recorded for 6 h, and subjective parameters (headache, flushing, oral tingling, visual disturbances, abdominal pain, nausea, palpitations, wheeziness, diarrhoea, flatulence, shivering and miscellaneous) for 24 h. No significant effects were observed, even with portions of spoiled mackerel containing 300 mg histamine, or mackerel from a batch which was reported to have been associated with an incident diagnosed as scombrotoxicosis.It is concluded that the precise combination of circumstances required to cause a scombrotoxic event were not reproduced in these studies, but it is tentatively concluded that histamine alone is unlikely to be the causative agen

ISSN:0022-5142    

DOI:10.1002/jsfa.2740470311

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY