摘要:

AbstractEver since limonin was first discovered in grapefruit (Citrus paradisiMacf) juice in 1965 and found responsible for significantly contributing to bitterness in the juice, a great deal of research has been directed towards understanding its role therein. Information is presented relative to limonin's chemical determination, taste threshold and content in grapefruit juice, and to relevant legislation. Also considered are (1) several factors affecting the limonin content of grapefruit juice (2) the effect of limonin content on sensory flavour in grapefruit juice (3) the interaction between the Brix: acid ratio and limonin content in affecting grapefruit juice flavour and (4) methods for reducing limonin in citrus juices generally. Finally, recommendations for future studies on limonin in grapefruit juice are reviewed.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740490402

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe trans isomers of methyl and t‐butyl esters of p‐coumaric acid and 4,4′‐ dihydroxy‐α‐truxillic acid were compared with trans‐p‐coumaric acid in relation to their toxicity against rumen microorganisms. Toxicity was evaluated by the effect on growth of pure cultures ofBacteroides ruminicolaandRuminococcus flavefaciensand by the effect on dry matter loss in in‐vitro digestion studies using rumen fluid. Growth of the pure cultures of rumen bacteria was reduced by the methyl and t‐butyl esters as much as or more than byp‐coumaric acid. In contrast, 4,4′‐dihydroxy‐α‐truxillic acid, a photodimer of p‐coumaric acid, was only marginally inhibitory to growth of these bacteria. At 5 mM concentration in rumen fluid, the esters inhibited dry matter digestion of bermudagrass by rumen bacteria and by fungi, but results for 4,4′‐dihydroxy‐α‐truxillic acid were similar to the control treatme

ISSN:0022-5142    

DOI:10.1002/jsfa.2740490403

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractKiwifruit (Actinidia deliciosa(A Chev) Liang et Ferguson cv Hayward) were harvested at a range of maturities, from 4.4‐8.9% w/v soluble solids, and ripened, with or without ethylene, after harvest or after storage for up to 12 weeks at 0 or 4°C.During maturation, the internal ethylene concentration of the fruit increased, and the lag before the onset of rapid softening decreased. Fruit harvested late in the season and ripened at 20°C softened as rapidly as similar fruit treated with ethylene. This occurred both immediately after harvest and after 6 weeks in storage at 0°C. In more mature fruit, and fruit stored at 0°C, the difference between core and flesh firmness was greater than in immature fruit or that ripened at 20°C immediately after harvest. After 6 weeks in storage, softening of the flesh was almost complete and core firmness had the greatest influence on fruit firmness.Soluble solids concentration increased as fruit softened, but during the first phase of softening soluble solids concentration was higher if the fruit were at low temperatures (or at 20°C without ethylene treatment) than if they were ethylene treated and held at 20°C. Sucrose increased and starch decreased during softening regardless of treatment. Citrate decreased during softening at 20°C and 12 weeks in storage at 0°C. Fructose/glucose ratios were lower in ethylene‐treated fruit than in untreated fruit. Malate did not change much on ripening after harvest but increased in response to low temperature, especially during storage at 4°C. These differences were also found in the eati

ISSN:0022-5142    

DOI:10.1002/jsfa.2740490404

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractStudies were carried out on the in‐vitro availability of iron to determine the effect of addition of tea, milk and ascorbic acid to a standard cereal meal in all possible combinations.The availability of iron from the cereal meal was low (3.92%). Tea, when added to the meal, had a significant depressing effect on available iron (2.56%). Addition of 100 mg ascorbic acid or 200 g milk completely counteracted the inhibitory effect of tea, and addition of both ascorbic acid and milk brought about an even greater enhancement in the in‐vitro availability of iron than when either was added alone. This investigation reveals that milk is as effective a factor as ascorbic acid in counteracting the depressing effect of tea on in‐vitro iron availab

ISSN:0022-5142    

DOI:10.1002/jsfa.2740490405

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractFungi isolated from fibreboard cartons, paper sacks and jute sacks were assessed for their ability to methylate 2, 4, 6‐trichlorophenol in a defined, reduced‐water‐activity growth medium. When extracts of individual cultures were analysed by gas chromatography‐multiple ion monitoring mass spectrometry, 17 of the 31 species, initially selected by sensory techniques, were found to produce 2, 4, 6‐trichloroanisole. Quantitative analyses showed that the most efficient methylators in the defined liquid medium were Paecilomyces variotii, Fusarium oxysporum, Penicillium crustosum, Pen citrinum, Pen brevicompactum and one strain of Aspergillus flavus. The role of these fungi in the production of 2, 4, 6‐trichloroanisole in packaging materials contaminated with 2, 4, 6‐trichlorophenol

ISSN:0022-5142    

DOI:10.1002/jsfa.2740490406

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractPhytic acid content of various cultivars showed a narrow variation: 7.48‐8.00 g kg−1and 6.47‐6.68 g kg−1for chickpea (Cicer arietinumL) and black gram (Vigna mungoL), respectively. Phytic acid was lowered significantly by the common methods of domestic processing and cooking including soaking, cooking, autoclaving and sprouting of the legume grains. Sprouting had the most marked phytic acid lowering effect followed by autoclaving and soaking. Cooking of soaked seeds lowered phytic acid by 20‐26% in chickpea and 35‐40% in black gram grains whereas the loss was 7‐11% and 6‐9% in these pulses, respectively, when unsoaked se

ISSN:0022-5142    

DOI:10.1002/jsfa.2740490407

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractChanges in the activities of major enzymes and in the proportion of the principal chemical components during the nataral fermentation of ugba from African oil bean (Pentaclethra macrophyllaBentham) were studied. The activities of the enzymes were related to changes in chemical composition. α‐Amylase, proteolytic and lipolytic enzyme activity remained detectable throughout the 72‐h fermentation period, and reached a maximum at 24‐36 h. The levels of amino nitrogen, ammonia nitrogen, reducing sugar, titratable acidity and pH increased with time. A seven‐fold increase in the amino nitrogen level occurred during the fermentation. The temperature of the fermentation and the moisture level reached maximum values at 24 h and 48 h of fermentation respectively. These results could provide useful indices for the improved evaluation of ugba ferm

ISSN:0022-5142    

DOI:10.1002/jsfa.2740490408

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractPearl millet flour/buttermilk mixture was fermented at 35, 40, 45 and 50°C for 3, 6 or 9 h to preparerabadi. Fermentation at all temperatures decreased phytate P, increased non‐phytate P and increased HCl extractability of P, Ca, Fe, Zn and Cu; the extractability increased with an increase in the period of fermentation. The largest improvement was seen in extractability of Fe, followed by that of P, Zn, Ca and Cu. Mn extractability did not change as a result of fermentati

ISSN:0022-5142    

DOI:10.1002/jsfa.2740490409

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractAn unusual spoilage condition of chill‐stored normal pH vacuum‐packed beef characterised by gross distension (blowing) of the packs and off‐odours perceived on initial opening of the packs as ‘sulphurous’ and subsequently as ‘fruity’, ‘solvent‐like’ and ‘strong cheese’ has been chemically defined. Hydrogen and carbon dioxide were the major components of the headspace gases. Other components included hydrogen sulphide, methanethiol, dimethyl sulphide, dimethyl di‐ and trisulphides, methylthioacetate, l‐butanol, acetic and butanoic acids, and l‐butyl esters of a range of C1‐C6fatty acids. Published sensory data are consistent with components of this mixture being responsible for the off‐odours detected. When grown in pure culture on beef under identical storage conditions, a Clostridium sp isolated from one of the blown packs produced the same chemical and

ISSN:0022-5142    

DOI:10.1002/jsfa.2740490410

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractForty blackcurrant (Ribes nigrumL) genotypes, including cv Baldwin and cv Ben Lomond as standards, were assessed for juice processing qualities. Regression analyses showed no significant variation in the rate of loss of total pigments but significant variation in the rate of loss of individual major pigments. Genotypes with a high delphinidin to cyanidin ratio showed no greater colour stability than genotypes with low ratios, which indicated that the difference between the stability of the major pigments was not great enough to exert a stabilising effect on the total pigment concentration. The variation in total pigment concentration appeared to be the main factor contributing to the greater stability of cv Ben Lomond juice colour compared with cv Baldwin juice colour.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740490411

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY