GRASSLAND RESEARCH ON BLANKET PEAT IN IRELAND

The results from 10 years of grassland research at the Peatland Experimental Station, Glenamoy, are summarized.
Grass and legume species were introduced by surface seeding, without cultivation or by direct seeding after rotavation, depending on the specific situation. The rate of establishment was dependent on pretreatment and the management of grazing animals before and after sowing.
The most suitable species were Trifolium repens, Lolium perenne, Festuca arumlinacea, Festuca rubra and Holcus lanatus .
A level of fertility suited to the introduced species must be reached initially and subsequently maintained. The requirements (per/ac) for Ca, P, K, N, Cu and Co were: 2240 lb (1016 kg) ground limestone, 36 lb (16 kg) P, 112 lb (51 kg) K, 20 lb (9 kg) N, 20 lb (9 kg) CuSO₄ and 2 lb (0–91 kg) CoSO₄ at sowing, with 27 lb (12–25 kg) P and 56 lb (254 kg) K annually.
Dry–matter yields of 6000 lb/ac (6720 kg/ha) were obtained from grass–clover swards without fertilizer N, and approximately twice this quantity where 400 lb N/ac (448 kg/ha) had been applied annually. A liveweight gain of 526 lb/ac (589–12 kg/ha) and a starch equivalent output of 2946 lb (3299–5 kg) were obtained with sheep. The relationship between these results and those on peat soils abroad are discussed.     

The Response to Epsom Salt Sprays of Mature Apple Trees of Three Varieties on Two Contrasting Rootstocks

Mature trees of Beauty of Bath, Tydeman’s Late Orange and Laxton’s Superb on M.VII rootstock, growing under commercial-type conditions, were severely deficient in magnesium as shown by leaf analysis and typical symptoms. Five sprays yearly of 2% Epsom salt (MgSO₄.7H₂ O) raised the concentration of magnesium in the leaves and largely eliminated symptoms: the concentrations of calcium and, to a lesser extent, of potassium in leaves were reduced. Over six years, there was little effect of Epsom salt on growth as measured, but crop weight was increased by 19–39% according to variety: this was largely, but not entirely, due to increase in fruit set. The proportion of fruit that dropped was decreased for Beauty of Bath and for Tydeman’s Late Orange sprayed with Epsom salt and the weight per 100 fruits of the late varieties Tydeman’s Late Orange and Laxton’s Superb was increased. Untreated trees on M.II rootstock, in contrast to those on M.VII, showed almost no foliar symptoms of magnesium deficiency, made more growth and produced larger crops; the concentrations of magnesium and calcium in the leaves were higher whereas potassium was usually lower. Epsom salt sprays did not increase growth or cropping; indeed, there was a tendency for sprays to reduce the crop weight of Beauty of Bath on M.II, indicating that they should not be used indiscriminately.

Epsom salt foliar sprays increased the “available” magnesium in the soil to a level considered to be medium—high; this effect was mainly shown in the top 6 in. of soil and gradually diminished to the 18–24 in. zone. Nevertheless, in the year following the termination of treatments, the proportion of foliage affected in Laxton’s Superb on M.VII, previously sprayed with Epsom salt, was almost as great as that of untreated trees and the concentration of magnesium in the leaves was as low. It appeared that magnesium in the soil did not reach the leaves.

The increase in “available” magnesium due to sprays was greater in soil carrying trees on M.II than M.VII, a result probably due to the extra quantity of spray required for these larger trees.     

Modifications of wheat flour proteins during in vitro digestion of bread dough, crumb, and crust: an electrophoretic and immunological study

The proteins of wheat flour have several biological activities that can affect human health and physiology when wheat-based foods are consumed. The modifications of bread crumb and crust proteins during an in vitro peptic/pancreatic digestion process were studied by electrophoresis and immunoblotting with polyclonal antibodies specific for single proteins or groups of homologous proteins of the wheat flour, and the results were compared to those obtained for an unheated dough sample. The results show that baking affects the extent of proteolysis and the immunological and physicochemical features of the digestion products in relation to the level of the heat treatment. Therefore, the results concerning the digestion of the unheated wheat flour or dough are not representative of what happens when baked products enter the human digestive tract.     

Determination and toxicity of saponins from Amaranthus cruentus seeds.

The concentrations of four triterpene saponins present in amaranth seeds were determined with high-performance liquid chromatography. It was shown that the total concentration of saponins in seeds was 0. 09-0.1% of dry matter. In germinating seeds an increase in concentration to 0.18% was observed after 4 days of germination, which remained stable for the next 3 days and later dropped to 0.09%. Highly purified extracts from the seeds were tested for their toxicity against hamsters. The hydrophobic fraction obtained by the extraction of seeds with methylene chloride showed no toxicity; the behavior of tested animals was similar to that of the group given an equivalent dose of rapeseed oil. A crude saponin fraction, containing approximately 70% of pure saponins in the matrix, showed some toxicity; the approximate lethal dose was calculated as 1100 mg/kg of body weight. It is concluded that low contents of saponins in amaranth seeds and their relatively low toxicity guarantee that amaranth-derived products create no significant hazard for the consumer.     

Kinetic study of the thermal hydrolysis of Agave salmiana for mezcal production

The kinetics of the thermal hydrolysis of the fructans of Agave salmiana were determined during the cooking step of mezcal production in a pilot autoclave. Thermal hydrolysis was achieved at different temperatures and cooking times, ranging from 96 to 116 °C and from 20 to 80 h. A simple kinetic model of the depolymerization of fructans to monomers and other reducing sugars and of the degradation of reducing sugars to furans [principally 5-(hydroxymethyl)furfural, HMF] was developed. From this model, the rate constants of the reactions were calculated, as well as the pre-exponential factors and activation energies of the Arrhenius equation. The model was found to fit the experimental data well. The tradeoff between a maximum fructan hydrolysis and a critical furan concentration in allowing for the best ethanol yield during fermentation was investigated. The results indicated that the thermal hydrolysis of agave was optimal, from the point of view of ethanol yield in the ensuing fermentation, in the temperature range of 106-116 °C and the cooking range time of 6-14 h. The optimal conditions corresponded to a fructan hydrolysis of 80%, producing syrups with furan and reducing sugar concentrations of 1 ± 0.1 and 110 ± 10 g/L, respectively.