engleski

Spray drying and liophylisation of carob water extracts by using different hydrocolloid carriers

Lipid oxidation is considered as a major cause of food quality deterioration affecting both its nutritional and sensory quality. This process is usually controlled by addition of different antioxidants. Bearing in mind numerous safety issues of most commonly used synthetic antioxidants, the need for efficient and safe natural antioxidant is increasing. Furthermore, such natural, plant derived antioxidants can also be used as active ingredients in wide variety of nutraceuticals and functional foods that should provide the protection of human organism against the oxidative stress. Due to its availability, low cost, chemical composition, and wide variety of proven biological effects, carob pods could be used as a valuable source of antioxidants not only in nutrition but also as food preservative or active ingredient of novel food formulations. In order to optimize the process of drying water extracts of roasted carob pods, we investigated the impact of different hydrocolloid carriers on the quality of dry carob powders obtained by spray drying and liophylisation. Water extracts, obtained by reflux cooking of roasted carob pods, were spray dried or liophylised using different carrier materials (β-cyclodextrin, γ-cyclodextrin and manitol) at different concentrations (1.6, 3.2 i 6.4 g/L). Powdered samples were characterised in terms of product yield, total phenolic content and ABTS antiradical activity analysis. The type of carrier material used in extract preparation had a significant influence on the antioxidative and technological properties of the products obtained. Manitol was found to be an unusable carrier for spray drying of carob extracts leading to the complete deterioration of the sample. The increase of carrier concentration during spray drying or lyophilisation led to the significant increase of antioxidant activity and the sample with the highest antioxidant activity was obtained for powder lyophilised with 6.4 g/L of manitol. Also, the lyophilised extracts with mannitol, regardless of its concentration, contained the highest amounts of phenolic compounds. Although the carriers used did not improve the water extraction of antioxidative compounds from the carob, they showed some protective action during the drying process. Transfer rates of biologically active compounds from water extracts during drying ranged from 37.9 % (spray dried carob, no carrier) up to 96.1% (lyophilized carob powder, 6.4 g/L β-cyclodextrin). Concerning the production yield, lyophilisation was found to be a method of choice for dry extract preparation, giving almost double yields compared to that of spray-drying process, regardless the type and concentration of carrier used. Taking all this into account, lyophilisation can be considered as the method of choice for preparation of carob powders with satisfying physico-chemical characteristics and significant antiradical efficiency.

spray drying; liophylisation; carob extract; hydrocolloid carriers

nije evidentirano