Moisture Adsorption and Thermodynamic Properties of California Grown Almonds (Varieties: Nonpareil and Monterey)

Abstract

Moisture adsorption characteristics of California grown almonds (Nonpareil: pasteurized and unpasteurized almonds; Monterey: pasteurized, unpasteurized and blanched almonds) were obtained using the gravimetric method over a range of water activities from 0.11 to 0.98 at 7-50ºC. The weights of almonds were measured until samples reached a constant weight. The relationship between equilibrium moisture content and water activity was established using the Guggenheim-Anderson-de Boer model. The diffusion coefficient of water in almond kernels was calculated based on Ficks second law. The monolayer moisture value of almonds ranged from 0.020 to 0.035 kg H2O kg-1 solids. The diffusion coefficient increased with temperature at a constant water activity, and decreased with water activity at a constant temperature. The thermodynamic properties (net isosteric heat, differential enthalpy and entropy) were also determined. The net isosteric heat of adsorption decreased with the increasing moisture content, and the plot of differential enthalpy versus entropy satisfied the enthalpy-entropy compensation theory. The adsorption process of almond samples was enthalpy driven over the range of studied moisture contents.

Moisture Sorption Behaviour and Mould Ecology of Trade Garri Sold in South Eastern Nigeria

“…Although differences in the moisture content between white and yellow garri were not significant, the observed difference may be attributed to the modulatory effect of lipid (palm oil additive) on the moisture sorption behavior of starchy food. Moisture sorption behaviour of lipid rich foods differ from that of carbohydrate or starch rich ones [ 26 , 28 , 29 , 52 , 53 ].…”

“…Knowledge of moisture sorption isotherms of dehydrated foods is valuable in solving food processing and engineering problems such as prediction of shelf life [ 25 – 28 ]. This has been successfully applied in the preservation of a number of dehydrated foods [ 29 – 31 ]. However, to our knowledge, this has not been studied in garri and a variety of dry food staples in the tropics, being also the countries most challenged by issues of food security.…”