摘要:

AbstractAt a time when agricultural surpluses and reduced farm subsidies are encouraging a reappraisal of the intensity of agricultural production, the role of free crops in reducing the load of fertilisers and herbicides on the soil is reviewed. Compared with agricultural systems, the use of chemical inputs in existing UK high‐forest systems is small. Trees are very efficient in their use of nutrients, and benefit from atmospheric additions. Losses through denitrification, ammonia volatilisation and leaching are small. Herbicide use is restricted to the first two or three years after tree planting, and usually to specific areas around each tree rather than over the site as a whole.The existing pattern of fertiliser use in forestry suggests that new tree crop systems on agricultural land will need small, if any, fertiliser inputs; herbicide use will be similar to current practice. The short‐rotation coppice system is the most demanding for both fertiliser and herbicide inputs, though its use is limited at present in the

ISSN:0022-5142    

DOI:10.1002/jsfa.2740570102

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe effects of supranutritional vitamin E supplementation in the diet on the growth performance of pigs, the deposition of α‐tocopherol in different tissues and the activity of certain blood enzymes were investigated. Pigs receiving diets supplemented with 100 and 200 IU vitamin E kg−1feed exhibited significant improvement in daily body gain and feed conversion efficiency in the early growth phase (P<0.05). With advance in age. the growth curves of pigs fed the higher levels of vitamin E tended to become parallel to that of the control group (10 IU vitamin E kg−1feed), suggesting that the advantage gained in body weight in the early growth period actually persisted in subsequent phases.The concentrations of α‐tocopherol in blood plasma and different tissues (heart, kidney, lung and liver) significantly increased (P<0.05) with increasing levels of dietary vitamin E. However, the activity of lactate dehydrogenase, creatine kinase and aspartate aminotransferase in blood plasma was not influenced by the levels of vitamin E supple

ISSN:0022-5142    

DOI:10.1002/jsfa.2740570103

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe influence of three levels of vitamin E in the diet of pigs on the subcellular deposition of α‐tocopherol in the muscle and on selected quality characteristics of pork meat (oxidative stability of lipids, colour, drip loss, microbial growth) was studied.The content of α‐tocopherol in adipose tissue and L. dorsi muscle as well as in mitochondrial and microsomal fractions of the muscle significantly increased (P<0.05) with increasing levels of dietary vitamin E. The differences in the concentrations of α‐tocopherol in the subcellular fractions were evident in the enhanced stability of the membranes when exposed to metmyoglobin/hydrogen peroxide.The beneficial effect of dietary vitamin E on the oxidative stability of pork lipids during the storage of pork chops and ground pork was also demonstrated. Even though lipid oxidation increased in all cases during storage, the pork products from the pigs receiving the highest level of vitamin E (200 IU kg−1feed) exhibited the smallest increase in thiobarbituric acid reactive substances. In addition, increased colour stability and decreased drip loss were observed on keeping pork chops, which had been previously frozen for three months, at 4°C under fluoresent light for 10 days. The possible effect of α‐tocopherol on membrane fluidity in this contex

ISSN:0022-5142    

DOI:10.1002/jsfa.2740570104

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractPectinesterase was isolated from Bramley apple waste (peel, cores and offcuts) and its characteristics were determined. Optimum pectinesterase activity was obtained between pH 7.0 and 9.5 and activity was still detectable at 5.0. The enzyme was stable over a wide pH range in the presence of substrate, with over 90% of the activity retained after 5 min at pH 2.5. Pectinesterase activity increased with temperature up to 60°. Activation energy was calculated at 32 kJ mol−1K−1between 20 and 50°. Optimum activity was obtained in sodium chloride concentrations between 0.025 and 0.20 M with activity declining at higher salt concentrations. A Kmof 0.044% apple pectin and a Vmaxof 9.52 units g−1DM were obtained for one specific enzyme

ISSN:0022-5142    

DOI:10.1002/jsfa.2740570105

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractDeveloping green seeds of two vegetable pigeonpea (Cajanus cajan L Millsp) cultivars that differ in their morphological characteristics were sampled at 24, 26, 28, 30 and 32 days after flowering (dates that are relevant to vegetable harvest). An increase in seed size was noticed between 24 and 26 days after flowering, although it continued up to 32 days after flowering. The dry matter accumulation as the seed matured was greater in ICP 7035 than in T 15–15. Analysis of freeze‐dried samples showed that soluble sugars, and proteins, decreased and starch content increased between 24 and 32 days after flowering. Calcium and magnesium contents were considerably higher in T 15–15 than in ICP 7035, but there was little difference in zinc, iron and copper contents. ICP 7035 contained significantly higher amounts of soluble sugars than T 15–15 at all stages of seed development: this indicates that it had sweet seeds, a requisite of vegetable pigeonpea cu

ISSN:0022-5142    

DOI:10.1002/jsfa.2740570106

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractWhite grape musts with added sulphur dioxide, ascorbic acid, glutathione, copper or flavanols were prepared and oxidised using known amounts of oxygen. Sulphur dioxide and ascorbic acid delayed caffeoyltartaric acid oxidation, 2‐S‐glutathionyl caffeoyltartaric acid (GRP) formation and browning development. The glutathione content determined the quantity of GRP formed; browning was prevented when all the caffeoyltartaric acid quinones generated by enzymic oxidation could be trapped as GRP. Cupric ions, which lower the concentration of available glutathione, enhanced must browning. Coupled oxidation of flavanols by the caffeoyltartaric acid quinones also led to increased discolorat

ISSN:0022-5142    

DOI:10.1002/jsfa.2740570107

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThree types of fresh sausages (beef, thick and thin; and pork, thick) were purchased in ten Sydney suburbs and analysed as composite samples for proximate principles, carbohydrates, vitamins, minerals, fatty acids and cholesterol. Fat, moisture and meat species were also analysed in individual purchases. In a controlled experiment replicate samples of sausages were analysed for moisture and fat, raw and after cooking by grilling, dry‐frying, shallow‐frying and deep‐frying. Results indicated widespread use of cow, pig and sheep meat in all types of sausages regardless of label identification. Some purchased sausages exceeded regulation limits for fat and starch content. Fat retention was lowest in beef sausages cooked by frying rather than grilling. Pork sausages retained most of their fat on cooking, regardless of m

ISSN:0022-5142    

DOI:10.1002/jsfa.2740570108

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractA conservative estimate of 800 000 T of red‐cotyledon microsperma lentil (Lens culinaris Medikus) is consumed annually after postharvest processing into split dehulled seed. This process consists of cleaning the seed of foreign matter, brief immersion in water, spin‐drying, standing to temper, separation into seed size fractions, dehulling/splitting and final separation. The effects of seed size (4 and 4.5 mm fractions), immersion times (1, 5, 10 and 30 min), temperature (19° and 36°) and duration (0, 30, 60 and 120 min) of air drying, and tempering time (0 and 24 h), on the efficiency of dehulling and splitting lentil were examined. Dehulling efficiency (%) was estimated as the sum of split dehulled seed, whole dehulled seed, and whole hulled seed (whole seeds are separated for recycling to the dehuller). Dehulling efficiency was best with the small seed fraction (4 mm), an immersion time of 1 min, no air drying, and a tempering time of 24 h. The drying air temperature did not have a significant effect on dehulling efficiency. Dehulling efficiency was highest with a low seed moisture co

ISSN:0022-5142    

DOI:10.1002/jsfa.2740570109

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractMost red‐cotyledon microsperma lentils (Lens culinaris Medikus) are utilised after postharvest processing into split dehulled seed. This study examined the effects on dehulling of 23 diverse genotypes of red‐cotyledon microsperma lentil, each grown at three sites ranging from 245 to 663 mm total seasonal rainfall in Lebanon and Syria. Dehulling efficiency (%) was measured as the sum of split dehulled seed, whole dehulled seed, and whole hulled seed. Despite a range in location means of 464–2018 kg ha−1for grain yield, the corresponding mean dehulling efficiencies varied only from 84.8 to 85.9%, indicating that the location effect on dehulling efficiency is of minor importance. There was more variation among genotypes for dehulling efficiency (80.8–87.7%) and for preparation of split dehulled seed (62.1–80.2%) than between locations. Seed processing variables showed medium to high broadsense heritabilities. Correlations between seed processing characters and agronomic variables were generally low. An approach to seed selection for optimum processing variables within the ICARDA breeding programme i

ISSN:0022-5142    

DOI:10.1002/jsfa.2740570110

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe thermal degradation kinetics of ascorbic acid and the inactivation kinetics of pectinesterase were studied experimentally with pH‐adjusted orange juice. No simple trends were observed in variation of the kinetic parameters with pH, but both kinetic functions agreed with kinetic compensation relations. An isokinetic temperature was observed for ascorbic acid degradation at pH 2.5, 3.0, and 3.5 implying that the same degradation mechanism was valid at these pH values. A large deviation at pH 4.0 from this isokinetic reaction rate implied that the degradation mechanism was different at this pH. There was no isokinetic temperature for pectinesterase inactivation reactions, indicating that pectinesterase was inactivated by different mechanisms at different pH values. The variation of the inactivation mechanism of pectinesterase with pH was attributed to its more complex molecular structur

ISSN:0022-5142    

DOI:10.1002/jsfa.2740570111

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY