摘要:

AbstractNitrogen content and composition of amino acids in juice and rind of navel oranges were studied. The compared varieties were ‘Navelina’ ‘Washington Navel’ and ‘Navelate’, early, mid‐season and late types, respectively. Total N content in juice increased during the season with values from about 60 to near 100 mg 100 ml−1in Navelina and ‘Washington Navel’ and from 60 to about 80 mg 100 ml−lin ‘Navelate’; amino N increased from 30 to 60 mg 100 ml−lapproximately in the three varieties. The total N content in rind was quite similar in all cases, with values that decreased with time from 1 to around 0·6 g 100 g−ldry weight (DW), 50–60% corresponding to the protein N. The main free amino acids in juice and rind at different maturity stages are tabulated. Proline represents at maturity around 50% of the total free amino acids in rind, with values near to 1·5 mmol 100 ml−lin juice and over 5·0 mmol 100 g−1DW in rind. Total protein amino acids in rind decreased during maturation, reaching final values of about 20 mmol 100 g−1DW. Differences in composition among t

ISSN:0022-5142    

DOI:10.1002/jsfa.2740430302

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe oxalate content of napier grass and of pearl millet × napier grass interspecific hybrids was studied in plants grown in midsummer in the field and in a phytotron under three temperature regimes. The plants in the field were irrigated every 3, 7 or 14 days and given at each irrigation a heavy application of nitrogen, not less than 5 kg N ha−1day−1. The plants in the phytotron were irrigated daily with a complete nutrient solution containing 200 mg l−1of nitrogen.The highest total and soluble oxalate contents in the dry matter of field grown plants were 2·6 % and 1·3%, respectively. The oxalate status of the plant was not affected by the irrigation or N fertilisation. In contrast, plants grown in the phytotron accumulated as much as 4·4 % of total and 3·4% of soluble oxalates, and both decreased with advancing maturity irrespective of the temperature regime.The content of sodium + potassium in the dry matter was linearly correlated with oxalate content (r2= 0·78) in the pooled data of all four experiments reported herein. There was no change in oxalate with N content above 2·0 % of the dry matter. Below that level oxalate increased Steeply with N content. However, in this range, N content is linearly correlated with (Na + K) content, and so its relation with oxalate is indirect.Oxalate levels in the leaves were higher than in the stems and decreased in both plant parts with advancing maturity. Only small differences in oxalates were found between the hybrids tested. Napier grass accumulated more oxalate in the stem than its F1hybrid, both having higher concentrations in tounger stem internodes. NO differences in ozalate levels were found between the leaves of he parent grass and its hybridIt is concluded that a hazardous concentration of oxalate in millet × napier hybrids is unlikely even under intensive N fertilisation. Consequently, consideration of oxalate accumulation need not be a constraint in breeding for imporved hybrids

ISSN:0022-5142    

DOI:10.1002/jsfa.2740430303

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractBy harvesting at different dates and frequencies, we have shown the influence of flowering on the essential oil of a clone of oregano grown under cultivation. Flowering increased the essential oil content. In non‐flowering plants the highest level of essential oil was obtained in June. The proportion of thymol and γ‐terpinene (1‐methy1–4‐(1‐methylethyl)‐1,4‐cyclohexadiene) in the essential oil varied during different months in non‐flowering plants as well as in different stages of flowering at the same date of harvest. Increase in the content of one of the two components was accompanied by decrease in the other one and vice versa. Flowering and season had no influence on the content of the other two main components in the essential oil (p‐c

ISSN:0022-5142    

DOI:10.1002/jsfa.2740430304

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA direct gas chromatographic method of identification and determination of 1‐triacontanol, a plant growth substance, in tea leaves is reported. Treatment of the tea leaves with calcium oxide releases more triacontanol, showing that the compound occurs also in a bound form in tea leave

ISSN:0022-5142    

DOI:10.1002/jsfa.2740430305

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractCowpeas, wheat flour and wheat grain infested with various developmental stages of, respectively,Callosobruchus maculatus (F)(Col: Bruchidae),Tribolium castaneum(Herbst) (Col: Tenebrionidae) andRhyzopertha dominica(F) (Col: Bostrichidae) were packed under vacuum or in CO2or N2atmospheres in plastic laminate pouches. After holding for up to 35 days the packs were opened and their contents incubated to allow survival to be assessed.Almost all eggs ofC maculatuswere killed when vacuum packed at chamber pressures of II kPa or less and held under vacuum for 14 days, whereas about 7% of young larvae survived these conditions. In contrast,R dominica wasmore difficult to control when packed as eggs; about 10 % and 2% of eggs laid survived to adulthood after two weeks following packing at II kPa and 0·9 kPa, respectively, whereas larvae and adults were all killed. Populations ofT castaneumeggs, larvae and adults were effectively controlled by vacuum packing at 11 kPa and holding for 7 days.None of the insects tested survived being packed in a CO2or N2atmosphere and held for periods ranging from 4 to 14 days.ManyC maculatussurvived vacuum and gas treatments when polyethylene film was used as packaging material. Control failures also occurred when pouches were punctured either by the commodity or by insects

ISSN:0022-5142    

DOI:10.1002/jsfa.2740430306

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractFarmed male red deer (15 and 26 months), fallow deer (16 months) and New Zealand wapiti‐type deer (26 months) slaughtered in an experimental abattoir were used to determine the influence of processing practices on tenderness and pH. Carcasses were electrically stimulated (low voltage) through the leg or anus immediately after bleeding and compared with non‐stimulated carcasses.Portions of loin and leg from all carcasses were subjected to a range of conditioning and ageing treatments before tenderness assessment was done with a Warner‐Bratzler shear press. Tenderness was measured in some samples after a freeze and slow thaw cycle.Electrical stimulation in all deer types had a highly significant effect in improving tenderness and the effects were most dramatic when carcasses were placed in a chiller 2 h after slaughter. Conditioning and ageing regimes (maximum 96 h post‐slaughter) further improved tenderness, particularly in non‐stimulated carcasses. Processing effects were more marked in loin pieces; these cooled more rapidly than leg.The process of freezing and slow thawing (20 h at 4°C in loins and 24–96 h at 0°C for legs) improved tenderness by 10–40% when compared with unfrozen pieces.There were highly significant reductions in the pH values of legs due to stimulation as measured during the early stages after slaughter. A decline in pH with time post‐slaughter was also evident. The results were consistent with the post‐slaughter pH profile of loins. Electrical stimulation, via either the leg or the anus, gave similar results. An exception was the loin pH measurement from anally stimulated wapiti stags which appeared higher than their leg‐stimulated counterparts.Where data were collected from both sides of leg‐stimulated carcasses, pH values were around 0.13 units lower for the stimulated shackled leg than for the free leg.Leg temperatures rose to over 40°C at 0.5 h post‐slaughter in all deer. Temperatures were generally similar between stimulated and non‐stimulated carcasse

ISSN:0022-5142    

DOI:10.1002/jsfa.2740430307

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractMinces were prepared from white muscle or fillets of gadoid and non‐gadoid fish species. After the addition of blood, kidney or formaldehyde the minces were stored frozen for 6 months at −8 and −30°C. Blood and kidney of the gadoid species contained trimethylamine oxide demethylase (TMAOase), whereas in the tissues of the other species no activity of this enzyme could be detected. The formation of dimethylamine (and formaldehyde) was correlated with the TMAOase activity of the added tissues. The concentration of haemoglobin in the minces had no influence on the dimethylamine and formaldehyde production during frozen storage. The formaldehyde production was accompanied by an increase in the firmness of the texture as measured by mechanical and sensory

ISSN:0022-5142    

DOI:10.1002/jsfa.2740430308

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractChemiluminescence was used to study the course of oxidation of sunflower oil samples at a number of temperatures between 70 and 121°C. The induction time was determined for each sample and used to estimate the shelf life of the oils at 25°C.In addition, Chemiluminescence during oxidation in air on alumina at 80°C was used to study both sunflower oil and, as a model compound, methyl linoleate with and without added artificial antioxidants. By using the method of inhibitors, the reaction rate and level of hydroperoxide were determined. It was also possible to determine the level of naturally occurring antioxidant in the vegetable o

ISSN:0022-5142    

DOI:10.1002/jsfa.2740430309

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0022-5142    

DOI:10.1002/jsfa.2740430301

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY