Ultisols and Oxisols in Malaysia are characterized by low pH and high Al, with their subsoils usually deficient in Ca, Mg, or both. An experiment, using polyvinyl chloride columns, was conducted to study chemical reactions in a representative Ultisol and Oxisol from Malaysia resulting from application of ground magnesium limestone (GML), gypsum, and their combinations. An increase in soil pH due to GML application in the Ultisol and the Oxisol resulted in an increase in negative charge on the soil surfaces in the zone of incorporation. Calcium was retained in that zone. In the gypsum‐treated soils, some Ca moved into the underlying horizons. Negative charge in the Oxisol increased from 2.8 to 3.7 cmolc kg−1 by an application of 8 t gypsum ha−1 due to specific adsorption of SO4 on Fe oxides. An increase in pH of the Oxisol due to SO4 adsorption and OH desorption was also observed. There was an accumulation of NO3 in the subsoils of the Oxisol and Ultisol as a result of gypsum treatment. The NO3 was adsorbed by the positively charged oxides. Leachate pH values were high at the beginning of the experiment, but the values decreased with time and were higher in the Oxisol than the Ultisol. This was attributed to a lower Al concentration in the leachate of the Oxisol. Effective alleviation of topsoil Al toxicity and subsoil Ca or Mg deficiency would require the application of 2 t GML together with 1 to 2 t gypsum ha−1.

Malaysian Ultisols and Oxisols are characterized by low pH, high soil solution AI concentration and Ca and/or Mg deficiencies, which are limiting to corn growth. An experiment was conducted to determine the changes in solid and soil solution phase properties of a representative Ultisol and Oxisol following applications of ground magnesium limestone (GML), gypsum and their combinations, and their effects on corn growth. A plot of p a l against lime potential (pH-1/2 pCa) showed that the points were mostly positioned between the theoretical lines for kaolinite-quartz and gibbsite equilibrium, reflecting the kaolinitic -oxidic mineralogy of the Ultisol and Oxisol. Gypsum application increased A1 concentration in the soil solutions of the Ultisol, but had no significant effect on that of the Oxisol. The increase in A1 concentration in the Ultisol was due to an increase in ionic strength. Gypsum application increased soil solution pH of the Oxisol due to release of OH as a result of ligand exchange between SO 4 and OH ions on the oxides of Fe and/or A1. Exchangeable A1 in both soils was reduced by gypsum application. The reduction was associated with solid phase immobilization through alunite formation; the soil solutions of soil samples treated with 2 and 4 t gypsum ha-1 were supersaturated with respect to alunite. Application of GML at 2 t ha -1 together with 1-2 t gypsum ha -1 gave high top weight of corn. Relative top weight of corn was positively correlated with a soil solution Mg and Ca/A1 concentration ratio, but negatively correlated with soil solution A1 concentration. Foliar AI corn was positively correlated with soil solution A1 concentration. Soil solution A1 and Mg concentrations, and Ca/AI concentration ratio can be used as indices of soil acidity in Ultisols and Oxisols.

No abstract

Encapsulation has been used to overcome the problem of instability of functional pigments such as carotenoids from natural sources. In this study, b-carotene in carrot juice was spray dried with four different wall materials namely maltodextrin, resistant maltodextrin, octenyl succinate anhydride (OSA) starches Capsul (CAP) and HICAP-100 (HCAP). The objective of this research was to study the effects of various wall materials on physicochemical properties and stability of b-carotene powders along with its stability after incorporation into sugar confection. All four wall materials produced powders of acceptable quality in terms of moisture content, water activity, hygroscopicity, solubility as well as onset glass transition temperature. OSA starches exhibited better pigment retention post spray drying where juices encapsulated with HCAP showed the highest retention (94.34%). This was also represented in more orange Hue values (H°) in powders produced with CAP (53.93) and HCAP (53.33). Powders produced with HCAP also showed the longest half-life after storage at 4 °C, 25 °C, and 40 °C, as well as under exposure to light. Similarly, carrot powders produced with OSA starches also exhibited better b-carotene retention after production of hard candy confection. Though candies with HCAP encapsulated juices showed the highest b-carotene retention post candy processing, candies with CAP encapsulated carrot juices exhibited better long term stability after storage at 25 °C and 40 °C as well as under exposure to light.

No abstract