Spray-drying, aroma retention

It is used in spray-drying, for retention of volatile substances as aroma. 

Possibly the most important, and least understood, aspect of spray-dried flavorings manufacture is the role the wall material plays in this process. The polymers utilized for this product are controlled by FDA constraints, cost, finished product labelling considerations and compatability, functionality and historical usage. Given these considerations, polymers selected for the retention and maintenance of labile flavors and aromas in industrial spray dried, food grade systems include both carbohydrate (hydrolyzed starches, "lipophilic starches, plant exudates) and protein. The importance of these wall materials should not be underestimated. 

Following preliminary hypochlorite treatments, a coherent process path was identified and implemented. Corn starch was oxidized with 6.4% (w/w) hypochlorite for two hours and given a combined base-heat gelatinization process (Method A). This base material exhibited excellent physical characteristics (i.e., stable emulsion with 20% db lemon oil incorporation into an aqueous dispersion, low lemon oil vapor phase flux (low headspace content), lack of inherent flavor and aroma) and when finally tested for spray dried lemon oil (20% db) retention efficiency in a lab-scale mini-dryer, the viability of this polymer was ascertained. Nearly 70% of the added lemon oil was retained following the drying of this DE 1.45 starch, a measure of functionality matched only by gum arabic (34). 

Coumans WJ, Kerkhof P, Bruin S. 1994. Theoretical and practical aspects of aroma retention in spray drying and freeze drying. Drying Technology 12 99-149. 

It was observed higher retention of VA compared to DA (MW VA > DA volatility VA < DA) and better retention with whole milk (due to fat phase) compared to skim milk. The partial replacement of maltodextrin by sucrose (smaller MW) is favorable to departure of aroma molecules with water during spray-drying. 

The study of volatile diacetyl retention (BP 88°C) in various constituents of milk (lactose, fat, proteins) during spray-drying showed the importance of amorphous/crystalline ratio in lactose for aroma retention that is in tnm linked to glass transition phenomena, temperature, and water/RH. The presence of microcrystals in drops (concentration, fast drying) may be a barrier to diffusion of volatile molecnles, therefore increasing the retention in the final spray-dried powder. 

M.V. Galmarini, M.C. Zamora, R. Baby, J. Chirife, V. Mesina, Aromatic profiles of spray-dried encapsulated orange flavours influence of matrix composition on the aroma retention evaluated by sensory analysis and electronic nose techniques. Int. J. Food Sd. Technol. 43, 1569-1576(2008)... 

The retention or loss of aroma compounds is also influenced by the structure (amorphous or crystallized) of the dried product Structural changes can be used for spray drying encapsulation processes (Bhandari et al., 1992 Re, 1998). Crystallization tends to increase the loss of aroma, because it rejects impurities, including volatiles. Senoussi et al. (1995) measured the loss of diacetyl as a function of the rate of crystallization of lactose during storage. They found that when the lactose was stored at 20 °C above the glass transition temperature Tg, the amorphous product immediately crystallized and practically all diacetyl was lost after 6 days. Levi and Karel (1995) also found increased rates of loss of volatile (1-n-propanol) as a result of crystallization in an initially amorphous sucrose system. 

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