Effect of processing on in vitro digestibility of protein and starch in quinoa seeds

The in vitro digestibility of protein in raw quinoa assessed by an enzymic method was 78%, significantly ( P > 0.01 ) lower than that of casein, 91%, and also somewhat lower ( P > 0.01) than that of the raw washed quinoa sample, 83%. the process used to remove the outer layers of the seeds containing saponins increased the protein digestibility significantly ( P > 0.01), by 7%. Heat treatments increased protein digestibility over that of raw quinoa samples. Only the cooked sample treated for 60 min presented a slightly lower protein digestibility, 77%, than those obtained for other heat-treated samples.
The temperature, time and moisture used in cooking and autoclaving of whole seeds of quinoa did not improve starch digestibility significantly. the digestibility of the starch in the raw and precooked samples was 72 and 77%, respectively, after drum drying and about 64% after extrusion in both cases. Precooking at 60°C for 20 min does not improve the digestibility of the quinoa starch.     

Pressure Acid Leaching of Nickel Laterites: A Review

Abstract

A review of the literature over the past 30 years on the processing of nickel laterites by high temperature acid leaching has been carried out to provide a better understanding of the mineralogy, leaching process chemistry and effect of operating conditions on nickel recovery, residue properties and scaling. Particular attention is paid to the leaching experience of the commercial Moa Bay plant and to the recently reported testwork and flowsheets associated with the three Western Australia lalerite plants that will be operating in 1999.

It is shown that laterites can vary significantly in their mineralogy according to location, climate and depth, and that the main host minerals for nickel and cobalt can be either goethite (iron oxide) or nontronite (clay) or manganese oxides. The mechanism of leaching involves acid dissolution of the host mineral lattice followed by hydrolysis and precipitation (transformation) of a variety of insoluble oxides and sulphates of iron, aluminium and silica under the high temperature conditions. Optimum leaching conditions and final liquor composition varies according to the ore mineralogy. More fundamental studies have demonstrated that the rate of leaching and character of the residue is dependent upon the level of Mg, Mn and Cr in the ore, the Eh of the slurry and salinity of the process water.

A number of studies are reviewed on the chemistry and precipitation of iron, aluminium, magnesium and silica to understand how the process conditions affect the solubility of the species and the nature of the scale which they form. Early work at Moa Bay indicates that the incorporation of chromium into alunite scale also affects the incorporation of silica and nickel and the settling of the residues. Various types of scale have been identified during different stages of leaching and possible means of minimising scale are discussed.

The clay-rich nickel laterites in Western Australia differ from Moa Bay laterite in mineralogy and have comparatively high silica and low chromium content. Since no commercial plant has previously processed such ores or used saline process water, there is little published in this area. It is therefore recommended that further research be carried out on understanding the process chemistry and species equilibrium from various ore types under autoclave conditions.     

The shelf-life of dairy products: 2. Raw milk and fresh products

In the second of this series of articles, the specific factors controlling the shelf-life of raw milk, pasteurized milk and cream, cottage cheese and yogurt are considered. The shelf-life of raw milk depends on the quality of the milk ex-farm and on subsequent transport and storage conditions. Shelf-life may be enhanced by deep cooling or thermization. Post heat treatment contamination by Gram negative psychrotrophic bacteria is the major determinant of shelf-life of pasteurized products. In cultured dairy products, yeast and mould contamination is the most usual cause of spoilage.     

The shelf-life of dairy products: 3. Factors influencing intermediate and long life dairy products

In this, the third part of a series of four reviews, the factors -which control the shelf-life of long and intermediate life dairy products are discussed. Two distinct types of product degradation are addressed. Firstly, the degradative potential of heat-resistant lipase, protease and phospholipase, derived from psychrotrophic bacteria commonly found in refrigerated milk, is examined. Secondly, the chemical composition of milk is reviewed and lipid oxidation, calcium induced aggregation of milk protein and Maillard reaction are identified as likely routes to product spoilage. The relative importance of these reactions to specific products will be discussed in the final part of this series of articles.     

Milk compositional quality — opportunities for manipulation

Widespread discussion of the effects of fat in the diet and the publication of the report of the Committee on Medical Aspects of Food Policy (COMA, 1984) have created an interest in the possibilities of manipulating the fat content of milk from the dairy cow. The two most practical methods seem to be through nutrition and breeding. However, the former would be expensive and the latter would take many years. Genetic engineering techniques may produce more rapid results but would create problems of both an ethical and an economical nature.     

Effect of nisin on the shelf-life of pasteurized double cream

Nisin was found to extend the shelf-life of pasteurized double cream if post-pasteurization contamination was eliminated. Nisin had little effect on the organoleptic properties of cream but enhanced proteolysis by Gram-negative organisms. A negative correlation was observed between nisin degradation in the cream and extension of the shelf-life. There was also a correlation between nisin degradation and the extent of proteolysis in the creams.     

Devolving Housing Policy and Practice in Northern Ireland 1998-2002

This paper reviews the effect of devolution on housing policy and practice in Northern Ireland. It outlines the history and context of devolution and housing policy in Northern Ireland, including the legacy and persistence of intense social conflict. Current devolution arrangements are reviewed, including the implications of enforced coalition for policy governance. The paper focuses on three dimensions of housing and housing-related policy development and implementation: social housing, especially the distinctive history and changing organisation of social housing provision; policies affecting the housing market, including the changing regime for spatial planning; and, regeneration and tenant participation. The paper argues that housing policy has tended to converge with policies in England, rather than moving towards a distinctively local agenda. Local political agendas remain dominated by disagreements over constitutional status thus policy formulation is determined more by officials than by elected politicians.