journal article
LitStream Collection
Home
Knight, A. H.; Crooke, W. M.; Shepherd, H.
doi: 10.1002/jsfa.2740230302pmid: 5023201
Normal methods of plant analysis proved suitable for the analysis of pollen, despite its extremely durable and unique outer coat of sporopollenin. The cation‐exchange capacity (CEC), uronic acid content (UA) and mineral composition of pollen from 53 Angiosperm and 5 Gymnosperm species were determined. The values found were of the same order as those of leaves, roots and seeds of the same species. Only minor differences in composition and CEC exist between pollen of monocotyledons (monocot) and dicotyledons (dicot), in marked contrast to other plant tissues, where generally the CEC and levels of elements in the dicot plant are higher than in the monocot plant. Relationships connecting CEC with uronic acid, total cations and nitrogen, already established for leaves and roots, also held for pollen although the correlation coefficients were not so high. On the other hand, correlations between CEC and individual cations, especially Ca, in pollen tended to be higher. Pollen of the same species from England and Sweden had similar UA contents (r = 0.91***), suggesting that this constituent and its related CEC value may be characteristic of a species and relatively independent of external soil nutritional factors, as has been found for root CEC.
doi: 10.1002/jsfa.2740230303pmid: N/A
A semimicro modification of the Olsen method was developed to include nitratenitrogen in the total soil nitrogen determination by the standard semimicro‐Kjeldahl method. The modified method was found to include nitrate‐nitrogen effectively from standard nitrate solutions and soils. It was significantly superior to the commonly used salicylic acid method, which was found to give incomplete recovery of nitrate‐nitrogen. In addition, changes in a number of experimental conditions such as amounts of water present and concentrated sulphuric acid used did not affect the results obtained by the modified Olsen method. In comparison with the recently recommended Raney catalysts for nitrate‐nitrogen inclusion in the total nitrogen determination of fertilisers, preliminary results using standard nitrate solutions and following their additions to the soil indicate that reduced iron was comparable. Results obtained using glucose as a reducing agent in the standard semimicro‐Kjeldahl method suggest that some nitratenitrogen was included by soil organic matter in the normal total soil nitrogen determination.
Fockens, F. H.; Meffert, H. F. Th.
doi: 10.1002/jsfa.2740230304pmid: N/A
The relation between biophysical properties of the skin of horticultural products and the rate of moisture loss under different ambient conditions is explained by a mathematical model. The numerical values of these properties can be determined by a simple experimental method. The effect of different air velocities on the loss of moisture from the products during cooling down is derived mathematically. The theory has been proved by experiments.
doi: 10.1002/jsfa.2740230305pmid: 5061661
A simple method has been developed for the determination of cobalt in plant material by atomic absorption spectrophotometry. The ashed sample was dissolved in 0.1 N‐HCl and the cobalt present chelated with ammonium pyrrolidine dithio‐carbamate. The chelate so formed was extracted and concentrated from the aqueous solution with methylisobutylketone, and this organic phase was presented to the atomic absorption spectrophotometer. Cobalt concentrations from 0 to 0.5 p.p.m. were determined. The efficiency of extraction was estimated using cobalt 60. Concomitant spectrographic analyses together with recovery experiments and replicate analyses showed that the method was suitably accurate for analysing plant material for its cobalt content in nutrition studies.
Ravindranath, R.; Khan, R. Yousuf Ali; Obi Reddy, T.; Thirumala Rao, S. D.; Reddy, B. R.
doi: 10.1002/jsfa.2740230306pmid: N/A
The physical and chemical characteristics of raw and coffee bean (seed) and spent grounds (a byproduct of the instant coffee industry) and the corresponding oils of four varieties of Indian coffee beans were studied. The chemical characteristics of the oils were found to be similar to those of groundnut oil except for the unsaponifiable matter which is high in the case of coffee bean oil (6–12%). The colour of crude coffee bean oil varied from light green (from raw bean) to chocolate brown (from roasted and spent grounds). The oil is practically odourless. Practical aspects of drying and storage of sludge and solvent extraction of dried grounds are discussed.
Harper, K. A.; Beattie, B. B.; Pitt, J. I.; Best, D. J.
doi: 10.1002/jsfa.2740230307pmid: N/A
Abnormal softening in canned apricots from the Murrumbidgee Irrigation Area of N.S.W. was shown to occur following the growth of Rhizopus stolonifer on the fresh fruit. The softening developed irrespective of the maturity of the apricots or the orchard from which they were obtained. The softening process took place slowly during storage of the canned apricots at 20 °C and the optimum period for study of the disorder occurred 6 months after processing. The macerating factor (probably a pectolytic enzyme) was generated early in the growth of the mould on the fruit and sufficient was present 16 h after its inoculation to cause post‐processing softening; at this stage the disease was not apparent on the exterior of the fresh fruit which could easily pass factory inspection prior to canning. Mould growth was arrested by dipping the fruit in dichloran and this measure was partially successful in controlling softening.
doi: 10.1002/jsfa.2740230308pmid: N/A
A new technique for studying the staling of bread is described based on conductance and capacitance measurements on the isolated centre‐crumb. It is proposed that the observed changes (up to 17%) in the electrical properties are due to retrogradation of the starch as well as the changes undergone by the transforming protein. Moisture redistribution is thought not to play a significant role during staling of the crumb at temperatures of less than about 10 °C. At 36 °C the first‐order rate‐constant for the protein transformation was estimated to be 0.7 day−1 and 0.3 day−1 for the rate constant for retrogradation of the starch fraction of the crumb. At 0 °C, the protein transformation was insignificant and the rate constant for the starch change was 1.03 day−1. The thickness of the gluten membrane surrounding the starch granules in bread was approximated to be less than 1 μm.
doi: 10.1002/jsfa.2740230309pmid: N/A
A study has been made of the effect of level of treatment of hard sweet biscuit doughs with sodium metabisulphite (SMS) on dough consistency and some properties of the finished biscuits. The results obtained suggest that the elastic properties of this type of dough are associated with about 50% of the disulphide (SS) groups present in the flour proteins. The remaining SS groups contribute to the cohesion of the doughs. The reduced amount of energy input required during the formation of a dough sheet from doughs containing 225 p.p.m. SMS (flour weight basis) compared with that required for untreated doughs is shown to approximate to the bond energy of SS bonds broken by the action of the SMS.
doi: 10.1002/jsfa.2740230310pmid: 5023202
The presence of nucleotide material in whole starch grains was confirmed and the amounts of individual constituents present in a variety of starches were determined quantitatively. A rapid method for the isolation of starch grains from potato tubers to limit contamination by cell‐sap nucleotides was developed. This technique enabled reproducible nucleotide patterns to be obtained from comparable batches of starch. Of the material held by a strong anion‐exchange resin above pH 7.5, the adenine nucleotides were quantitatively dominant, only traces of UMP and GMP being detected. The relative amounts of AMP, ADP and ATP in the various starches fluctuated. ADP‐glucose was the only sugar‐containing nucleotide encountered and UDP‐glucose, although looked for, appeared to be absent in all cases.
Showing 1 to 10 of 17 Articles