Journal of the Science of Food and Agriculture
1097-0010
0022-5142
Anh Quốc
Cơ quản chủ quản: WILEY , John Wiley and Sons Ltd
Lĩnh vực:
Food ScienceNutrition and DieteticsBiotechnologyAgronomy and Crop Science
Phân tích ảnh hưởng
Thông tin về tạp chí
Journal of the Science of Food and Agriculture publishes peer-reviewed original research, reviews, and perspectives in these areas, with particular emphasis on interdisciplinary studies at the agriculture/ food interface. The journal focuses on hypothesis-driven research studies suitable for an international audience. Studies of local products or descriptive studies are discouraged.
Các bài báo tiêu biểu
Storage stability of coconut milk powder Abstract Spray‐dried coconut milk powder prepared with additions of skim milk and dextrin was stored in packages for 6 months at room temperature (30°C and 80% RH). The packaging materials used were aluminum laminate (vacuum and air packed) and polypropylene. The sorption isotherm of the powder showed that the monolayer of water molecules was complete when the relative humidity was 27% which corresponded to a moisture content of 5%. Measurements of water activity, moisture content, peroxide value and solubility index indicated that lipid oxidation is the limiting factor in the stability of the powder. Its maximum shelf‐life was 4 months when air or vacuum packaged in aluminum laminates and 1 1/2 months in polypropylene.
Tập 43 Số 1 - Trang 95-100 - 1988
Dissolution of potassium feldspar rocks in soils in open‐leaching and closed‐incubation systems Abstract The dissolution of two finely ground potassium feldspar rocks (KFR). from Malawi and Sri Lanka, was examined in four indigenous acid soils using open‐leaching and closed‐incubation systems. Increases in fractions of soil potassium (K), compared to the control, indicated that the extent of dissolution of KFR was usually substantially enhanced in the leaching system. Because the leaching system represents the field situation more closely, it is the most appropriate for assessing the dissolution of potassium feldspar rocks (KFR) in soils and their potential as direct‐application K fertilisers.
Tập 62 Số 4 - Trang 409-412 - 1993
Chemical compositions of the marine algae <i>Gracilaria salicornia</i> (Rhodophyta) and <i>Ulva lactuca</i> (Chlorophyta) as a potential food source Abstract BACKGROUND: The nutritional compositions of two edible red (Gracilaria salicornia ) and green (Ulva lactuca ) seaweeds were determined to evaluate their possible uses as potential food ingredients.RESULTS: In general, these species contained limited amounts of lipids ranging between 0.99 and 2.00 g 100 g−1 dry weight) and considerably high amount of minerals, especially in G. salicornia (38.91 g 100 g−1 d.w.). The crude protein values varied between 9.58 and 10.69 g 100 g−1 d.w. Amounts for total amino acids were 889.78 ± 22.64 mg g−1 protein d.w. in G. salicornia and 543.3 ± 15.14 mg g−1 protein d.w. in U. lactuca . The most abundant fatty acids were C12:0, C16:0, C20:4 ω6 and C22:5 ω3, in addition to C18:1 in G. salicornia . Both seaweed species were balanced sources of ω3 and ω6 fatty acids with a ratio of ω6/ω3 that varied between 1.2 and 1.17. Between the seaweeds investigated, high levels of K (2414.02‐11 380.06 mg 100 g−1 d.w.) were observed and the amounts of Ca, Na and Fe were higher than those reported for land plants.CONCLUSIONS: Thus, G. salicornia and U. lactuca may be utilised as value‐added products for human nutrition purposes. Copyright © 2012 Society of Chemical Industry
Tập 92 Số 12 - Trang 2500-2506 - 2012
The phenolic substances of manufactured tea. II. — Their origin as enzymic oxidation products in fermentation Abstract The brown acidic pigments and the yellow neutral pigments of black tea are provisionally named thearubigins and theaflavins respectively. These and other substances characteristic of black tea are formed during the fermentation process, mainly as the result of the enzymic oxidation of (—)‐epigallocatechin and (—)‐epigallocatechin gallate. It is probable that the theaflavins are intermediates in thearubigin formation.
Tập 9 Số 4 - Trang 212-216 - 1958
Tea cream formation: The contribution of black tea phenolic pigments determined by HPLC Abstract Reverse‐phase HPLC of liquors prepared from a Lattakari Assam black tea was used to assess the contribution of black tea phenolic pigments to ‘tea cream’, a precipitate which forms routinely following caffeine complexation of the phenols when a strong infusion of black tea cools. In this study caffeine was added back to tea liquor fractions and reconstituted decaffeinated whole tea liquor, and the extent to which the theaflavins, thearubigins and flavonol glycosides were removed from solution in the form of insoluble complexes was monitored by HPLC. The poorly characterised thearubigins are shown to be the principal (≈ 86%) pigmented phenolic components of ‘tea cream’. Theaflavins (≈ 12%) and flavonol glycosides (≈ 2%) were also present. Evidence is presented for a synergistic interaction between theaflavins and thearubigins during cream formation. The use of caffeine precipitation is proposed as an aid to the fractionation and quantification of phenols including thearubigins in black tea liquors.
Tập 63 Số 1 - Trang 77-86 - 1993
The phenolic substances of manufactured tea. I.—Fractionation and paper chromatography of water‐soluble substances Abstract Methods are described for the fractionation of the complex mixture of phenolic substances and their oxidation products occurring in manufactured tea. Products of oxidation detected include two fractions, S I and S II, responsible for the greater part of the colour intensity of a tea infusion, and nine unidentified substances, A, B, C, D, P, Q, X, Y and Z. S I and S II have been obtained almost free from other contaminants. They have acidic properties, and mean molecular weights of the order 600. They are probably mixtures of dimers, each dimer consisting of two oxidized flavanol units. X and Y have no acidic properties and are also distinguished from S I and S II by several characteristic colour reactions. P may be an anthocyanidin.
Tập 8 Số 2 - Trang 72-80 - 1957
Black tea thearubigins—their HPLC separation and preparation during in‐vitro oxidation Abstract A reverse phase, gradient elution HPLC method has been developed to separate black tea thearubigin compounds. Using diode array spectroscopy, spectral data are provided for the major pigment peaks. The analytical method has been used to monitor the formation of the thearubigin compounds during black tea fermentation. In‐vitro model fermentation systems using partially purified tea polyphenol oxidase and mixtures of six pure catechins have also been analysed. Data are presented to relate many of the thearubigins in black tea liquors to their catechin precursors. Manipulation of the in‐vitro model system conditions will be used to prepare various thearubigins for further structural studies.
Tập 50 Số 4 - Trang 547-561 - 1990
Effects of harvest stage and re‐growth on yield, composition, ensilage and <i>in vitro</i> digestibility of new forage sorghum varieties Abstract The effect of growth stage and re‐growth on the nutritional and ensilage characteristics of two new sorghum hybrids, BMR‐101 and Silobuster, and one commercial variety, FS‐5, was examined in this study. Varieties were sampled during the summer at the early heading (EH) stage and were harvested at the soft dough (SD) stage. Additional irrigation enabled autumn re‐growth and a second harvest. Plants of FS‐5 and BMR‐101 were resistant to lodging at EH. However, BMR‐101 and Silobuster suffered from high lodging at the SD stage of the summer harvest. Dry matter (DM) content of FS‐5 and BMR‐101 at EH was below 250 g kg−1 . DM yields of the varieties were similar at the summer harvest and higher than their respective re‐growth cuts. Ensilage DM losses were moderate and similar across varieties. Hemicellulose of SD plants was partly solubilised and most of the water‐soluble carbohydrate fermented, yielding lactic acid, ethanol and volatile fatty acids (VFA), and a pH < 4. In vitro DM digestibility of varieties was similar in summer silages, but lower in the respective re‐growth silages of FS‐5 and BMR‐101, reflecting the higher content of neutral detergent fibre and lignin in the re‐growth silages. The summer plus re‐growth cumulative yields of digestible DM of the respective FS‐5, Silobuster and BMR‐101 silages were 14.7, 16.6 and 14.5 t ha−1 . The commercial variety, FS‐5, may have some advantage over BMR‐101 and Silobuster owing to its relative resistance to lodging in addition to its high yield and good ensilage properties. Copyright © 2005 Society of Chemical Industry
Tập 86 Số 1 - Trang 140-147 - 2006
The sorption of iodide by soil components Abstract The sorption of iodide by several soil component materials was examined over a range of pH values and compared with sorption by a surface soil. A compost, prepared from grass roots which had been allowed to decompose for 24 weeks, sorbed substantial amounts of iodide from solution and showed changes in sorption, due to pH and drying, similar to those shown by the soil. Freshly precipitated hydrated ferric oxide also sorbed substantial amounts of iodide from solutions of pH < 5.5 but the amount decreased to zero as the pH approached 7. Sorption by freshly precipitated hydrated aluminium oxide was impossible to assess at pH < 5 owing to its solubility but at pH 5.5 to 7.5 its sorption was similar to that of ferric oxide. No sorption of iodide was detected by kaolinite, montmorillonite, chalk or limestone. Drying markedly reduced the capacity for iodide sorption of the compost and soil and had a smaller effect on the ferric and aluminium oxides.
Tập 25 Số 1 - Trang 73-79 - 1974
Ascorbic acid destruction in aqueous model systems: an additional discussion Abstract The influence of different non‐electrolytes (fructose, xylitol, glucose/mannitol mixture) and electrolytes (NaCl, KCl) on anaerobic L ‐ascorbic acid (AA) degradation in an aqueous model system (pH 3.5, a w 0.94) was studied to assess the effect on that reaction of substances commonly used to diminish the water activity of fruit or vegetable juices, as well as its relation with non‐enzymatic browning (NEB) development, at processing (70, 80, 90 °C) and storage (24, 33, 45 °C) temperatures. AA degraded as a function of time with a behaviour that could be described by first‐order kinetics at all temperatures studied, and activation energies could be calculated using the Arrhenius law. The presence of humectants enhanced AA destruction, with D ‐fructose promoting the fastest L ‐ascorbic acid destruction and browning development at processing temperatures. The influence of humectants on NEB seemed to determine differences between their influence on AA degradation. Water activity decrease by humectant addition produced higher AA stability in solution at storage temperatures. The differential effect of each humectant used to decrease the water activity seemed to be related to its influence on solvent structure. © 2001 Society of Chemical Industry
Tập 81 Số 15 - Trang 1433-1439 - 2001