摘要:

AbstractOak (Quercus incanaRoxb) leaves are rich in tannins and produce adverse effects when fed to livestock. The effects of shade and sun drying and oven drying at 60°C and 90°C for different lengths of time (24 to 72 h) on total phenolics, condensed tannins, protein precipitation capacity, degree of polymerisation, specific activity (protein bound per unit tannins), fibre‐linked proanthocyanidins, acid and neutral detergent fibres and lignin levels in mature oak leaves were studied. Removal/inactivation of tannins was not observed on wilting or drying under several conditions. Similarly the drying conditions had no effect on fibre composition. The adverse effects on feeding fresh or dried oak leaves are expected to be of similar magnit

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540302

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractPostharvest application of acetaldehyde (AA) vapour or anaerobic conditions of N2or CO2for 24 h to hand‐picked feijoa (Feijoa sellowianaBerg) fruits caused the accumulation of volatiles, which increased fruit aroma and flavour. The volatiles, AA, ethanol, ethyl acetate and ethyl butyrate, were produced at high concentrations in treated fruit held for 13 days in storage at 20°C whereas in the control fruits the levels remained very low. A sensory panel judged the treated fruits to be sweeter than the controls, although there was no significant difference in the total soluble solids or acidity between the treated and the non‐treated feijoas. Treatment with 98% N2for 24 h was most effective for volatile production. Moreover, fruits in the N2treatment maintained the best appearance after storage for 13 days at

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540303

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractCresolase and catecholase activities were determined in tubers of four potato (Solanum tuberosumL) varieties (Kufri Chamatkar, Kufri Chandramukhi, Kufri Sindhuri and C‐2703) fertilised with three levels (0, 120, 240 kg K2O ha−1) of either muriate or sulphate of potash. The enzyme activities were also determined separately in the peel and flesh tissues of the tubers of Kufri Chamatkar and C‐2703. Differences were observed in the activities between varieties, with highest specific activities in the tubers of Kufri Chamatkar. Peels of both the varieties showed higher cresolase and catecholase activities than the flesh tissue. Application of potassic fertilisers caused a reduction in both the activities in the tuber, peel and flesh tissue. Greater reduction in activities was caused by application of muriate of potash than with the sulphate

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540304

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractA direct comparison of two pre‐treatments was undertaken to test their effect on the recovery of phenolic acids (PA) from three forage species. Samples of lucerne (Medicago sativaL), reed canarygrass (Phalaris arundinaceaL), and switchgrass (Panicum virgatumL) were refluxed with 95% ethanol (EtOH) or neutral detergent solution (NDS). Subsequently, the resulting ethanol insoluble residue (EIR) and neutral detergent fibre (NDF) were treated with 1MNaOH, and the extract was assayed for concentrations ofp‐coumaric acid (PCA) and ferulic acid (FA). In lucerne, the concentration of PCA was 9 times greater in the EIR than in the NDF (0·90 vs 0·11 mg g−1dry matter, DM), and the FA concentration was 27 times greater in forage treated with EtOH than with NDS (1·89 vs 0·07 mg g−1DM). In reed canarygrass (RCG), the concentrations of PCA and FA were slightly though significantly higher when the forage was pre‐treated with EtOH. No significant differences in PA yield were detected between pre‐treatments in switchgrass (SG). Extraction of EIR with hot EDTA (0·025M, pH = 6·8) removed 80 to 90% of the total PA in EIR in lucerne but less than 5% of the PCA and FA in the grasses. These results indicate that almost all the PA in lucerne, in direct contrast to the grasses, are present in a fraction of the plant that is soluble in NDS. The relatively high PA concentration in the NDS soluble fraction suggests that the structure and composition of the fraction to which PA is esterified influence the degree to which PA affe

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540305

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractProduction of the phytase (EC 3.1.3.8) fromAspergillus ficuumin a submerged batch process was inhibited by high concentrations of glucose. The inhibition was overcome by applying a fed batch technique in the production of the enzyme. Tests carried out at different oxygen concentrations revealed that aeration had a beneficial effect on the production of the enzyme. The enzyme showed an optimum pH and temperature of 5·0 and 60°C, respectively. Preincubation of the enzyme preparation at 60°C resulted in relatively fast denaturation of the enzyme. Upon storage at 4°C it lost only 15% of its activity in 5 weeks.Aspergillus ficuumalso produced phytase when grown on canola meal by a solid state technique. The enzyme catalysed degradation of the phytic acid present in the meal and completely eliminated it, rendering the commodity more suitable for animal feed. An apparent 10% increase in protein content of the canola meal was noted as a result of the growth of the microorgan

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540306

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractNine varieties of finger millet (Eleusine coracanaGaertn) including a wild form were screened for proteinase and α‐amylase inhibitory activities. Subtilisin inhibitory activity was present in all the varieties examined and was highest in the wild form, while the cultivated varieties had more trypsin inhibitory activity. Isoelectric focusing of a 60% ammonium sulphate fraction of the wild form, before and after complexing with subtilisin, showed multiple forms of subtilisin inhibitors one of which was also active against trypsin. Isoforms of finger millet subtilisin inhibitors were isolated from the ammonium sulphate fraction by ion exchange chromatography on DEAE‐Sephadex followed by SP‐Sephadex chromatography. Copurification of trypsin and α‐amylase inhibitory activities with subtilisin inhibitory activity was observed during cation exchange chromatography. PAGE analysis revealed them to be charge isomers with pI in the range 5·5–6·0. SDS–PAGE gave an estimate of 12 000 mol wt for each of them. Finger millet subtilisin inhibitors were more active on bacterial proteinases than on bovine trypsin a

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540307

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe degradation by heat of surface colour and texture of pickled green olives has been studied with the aim of optimising the thermal treatments used for their conservation. A first order kinetics has been assumed in order to be able to quantify this degradation for temperatures between 70 and 100°C. The equations obtained for the thermal destruction times of colour (pasteurisation units at 60°C, PU = 16·2 min andz= 74·3 C) and texture (PU = 26·6 min andz= 62·8°C) allow affirmation that these organoleptic characteristics are not affected by the thermal pasteurisation treatments necessary to guarantee the product's sta

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540308

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe response of barley to foliar and soil applied zinc was studied at fire low soil zinc sites in south‐east Scotland over two season. None of the treatments increased the grain yield at harvest. Of the treatments studied only foliar applied zinc sulphate consistently increased the zinc content of plant tissue, and this was more marked when a split application of 2·5 + 2·5 kg ha−1Zn was used as opposed to a single treatment of 5 kg ha−1Zn. It is concluded that at the present time there is no evidence that zinc is limiting the yield potential of barley when grown on low zinc soils in this part of S

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540309

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractTLC analyses of lemon (Citrus limon(L) Burm f) fruit at various stages of maturity showed that limonoid glucosides were synthesised during the late stages of fruit growth. No limonoid glucosides were found in the stem and leaf. Use of radioactive tracers showed that14C‐nomilin was converted to14C‐nomilin 17‐β‐D‐glucopyranoside in fruit tissues and seeds. Glucosides are indeed the major end products of limonoid

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540310

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractA trypsin/chymotrypsin inhibitor (JSTI) was isolated from jack fruit seeds (Artocarpus integrifoliaHook f) by ammonium sulphate fractionation and chromatography on DEAE–cellulose and Sephadex G‐100. During all stages of purification, the ratio of trypsin and chymotrypsin inhibitory activities remained constant. The purified preparation was found to be homogeneous by gel filtration, polyacrylamide gel electrophoresis (PAGE) and ultra‐centrifugation. From the sedimentation coefficient,S20wvalue of 3·5 ± 0·15 S. the molecular weight of JSTI was calculated to be 30·00 ± 2·50 kamu. The inhibitor showed a molecular weight of 24·55 kamu on a Sephadex G‐75 column when eluted with 6Mguanidine hydrochloride, Under non‐denaturing conditions, JSTI exhibited anomalous behaviour on a Sephadex G‐200 column. On SDS–PAGE, the inhibitor showed two major bands with molecular weights of 26·30 and 15·00 kamu and two minor bands with molecular weights of 19·50 and 12·00 kamu. The carboxyamidomethylated JSTI showed three trypsin inhibitory activity bands on PAGE, suggesting the p

ISSN:0022-5142    

DOI:10.1002/jsfa.2740540311

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY