K. A. Buckle

Enthalpy-entropy compensation models for sorption and browning of garlic

The enthalpy-entropy compensation theory was applied to both the sorption and non-enzymic browning of garlic. The theory was found to explain sorption well but gave a non-linear relationship for browning. The resulting power law model for sorption was compared with the Guggenheim-Anderson-de Boer (GAB) model and found to predict higher moisture contents at high water activity levels.

Shrinkage, density and porosity of garlic during drying

Abstract The apparent density of garlic cloves (with a moisture content range of 10–65% wet basis) was evaluated by weighing the product in air and determining the corresponding buoyancy force in toluene. An analysis of variance (ANOVA) revealed a significant effect (P

BULK DENSITY, POROSITY AND RESISTANCE TO AIRFLOW OF GARLIC SLICES

ABSTRACT The bulk density of garlic slices at different moisture levels (ranging from approximately 3 to 65% MC wet basis) was determined by weighing the contents of a container of known volume. The porosity was calculated using its relationship with bulk and apparent densities. An analysis of variance (ANOVA) revealed that bulk density and porosity were affected significantly by moisture and slice thickness as well as the interaction of these variables. Bulk density varied in a positive linear fashion with moisture and thickness while a negative linear correlation was found for the calculated bulk porosity. The linear model met me adequacy criterion for characterising the behaviour of garlic. Using a laboratory unit, the vertical resistance to airflow through the product and die effect of moisture and slice thickness were investigated for an airflow rates of 0.09 to 1.2 m3/s-m2. A higher resistance to airflow was noted for the wet product with the experimental data fitting to Shedds model when the airfl...

PREDICTING THE SORPTION BEHAVIOUR OF GARLIC SLICES

ABSTRACT Moisture desorption properties of fresh garlic (cv. Early Californian) were investigated at 20 °C to 70°C and relative humidities ranging from 11% to 85% using the gravimetric static method. The slices were allowed to equilibrate in a constant humidity environment (hygrostats) maintained by salt solutions. The effect of temperature and relative humidity on the equilibrium moisture content was highly significant (P<0.0001). Four models available in the literature, namely the Chung-Pfost, modified Halsey, modified Henderson and the Guggenheim-Anderson-de Boer (GAB) were evaluated (the correlation coefficient, F-ratio and plots of residuals) to determine the best fit for the experimental data. On the basis of the F-test, The modified Henderson model was found adequate and the GAB model superior for characterising the sorption behaviour of garlic slices in the temperature and water activity range investigated.

Separation of chlorosphyll and carotenoid pigments of capsicum cultivars

Abstract A system of thin-layer chromatography on cellulose and column chromatography of mixed pigment bands on columns of magnesium oxide—Hyflo Super-Cel (1:1, w/w) and alumina was developed for the separation of chlorophyll, carotene and xanthophyll pigments in capsicum cultivars. A total of twenty six pigments were separated and identified in Large Green and Golden California Wonder cultivars, during maturation and ripening. Cellulose thin layers and up to four solvent mixtures enabled chromatographic separation without degradation of chlorophylls nd xanthophylls. Carotenoid hydrocarbons which travelled as one streak behind the solvent front on thin layers were separated on magnesium oxide—Hyflo Super-Cel and alumina columns.

Models for the Specific Heat and Thermal Conductivity of Garlic

ABSTRACT The proximate composition of garlic (cv. Early Californian) was determined and compared to values reported in the literature. The specific heat and thermal conductivity were determined using the method of mixtures and a modified Fitch apparatus, respectively and both approaches proved sufficiently accurate for such purposes. An analysis of variance revealed that moisture content had a highly significant effect on both specific heat and thermal conductivity of garlic. A linear empirical model was developed to characterise the specific heat as a function of moisture content. The model predictions were very close to values predicted on the basis of the proximate analysis. The measured thermal conductivity data were fitted to parallel, perpendicular and random structural models as weU as empirical mathematical expressions. The parallel and exponential models gave satisfactory agreement with the data.

Separation of carrot carotenoids on hyflo Super-Cel-magnesium oxide-calcium sulfate thin layers

Abstract A Hyflo Super-Cel-magnesium oxide-calcium sulfate (8:2:0.7, w/w/w) thin-layer chromatographic adsorbent was used for the separation of carotenoid pigments of fresh and dehydrated carrots. All carrot carotenoids were separated satisfactorily in one development on thin layers treated with water, and good pigment recoveries were achieved. The adsorbent was found to be sufficiently mild for use with carotenoid pigments, and has high resolving power for separation of the non-polar carotenes. The adsorbent containing 75% Hyflo Super-Cel is cheap and gives durable layers which are easy to handle.

True retention of nutrients on cooking of Australian retail lamb cuts of differing carcass classification characteristics

The true retention of nutrients (proximate principles and cholesterol) on cooking of three retail cuts from lambs classified by weight, sex and fatness score was investigated. Fat retentions of the total cut and of the lean portion of lamb legs and mid-loin chops were not affected by carcass fatness, weight and sex or their interactions, however, the fat retention of the total cut and of the lean portion of forequarter chops was affected by fat score, with forequarter chops from fat score 1 retaining more fat than did chops of carcasses of higher fat score. Overall, fat was lost by all cuts (total cut) on cooking, with only 70-80% of fat being retained, but fat content of lean only increased on cooking (retention >100%), indicating the passage of fat into the lean portion from the external fat cover during the cooking process. Carcass factors and their interactions had little or no effect on the protein, water and ash retentions of the total cut or the lean portions of the three cuts. Cholesterol retention by the lean portion of three cooked lamb cuts was not affected by any carcass factors or their interactions. Cholesterol retentions were ∼99% for total cuts and tended to be ∼102% for the lean portions.