Microencapsulation of bioactive compounds (antioxidants, vitamins, minerals, omega-3 lipids, probiotics, among others) has been increasingly studied in the last years due to the actual interest in nutraceutical components and functional food. The main objective of this technique is to protect the bioactive compounds from environmental conditions, which may diminish their functionality, such as oxygen, pH, humidity, light or temperature exposure. Among the different microencapsulation processes, spray drying produces a final powder product with good quality properties for distribution, transportation and storage. Different encapsulation agents have been studied for microencapsulation by spray drying in behalf of increasing the viability of the bioactive compounds and to promote an additional functionality to the final product as well, such is the case of prebiotics. Prebiotics are soluble non-digestible carbohydrates by humans but which selectively enhances Bifidobacterium and Lactobacillus growth (microorganisms commonly present in the human gut). Some examples of prebiotics are inulin, fructans (fructo-oligosacharides) or galacto-sacharides. Besides, several microorganisms (probiotics) have demonstrated benefic effects in humans which have been attributed to the lactic acid and short chain-fatty acids production, which reduces the pH of the colon, causing a decrease of the pathogenic bacteria survival.
In the present study, extracts of different natural sources (orange and grapefruit peel, artichoke and asparagus) are evaluated to determine their fructans content and use them as encapsulating agents for spray drying encapsulation of the probiotic Lactobacillus casei.
Previous to the extraction process with hot water at 85°C, the samples were cut in slices of 1cm width, dried in a hot air dryer at 35 °C for 48 h. Fructans content were determined by the AOAC methods 991.43 and 997.03 respectively. Aqueous solutions were prepared with the extracts and maltodextrin to achieve 25% p/p. The extracts and the solutions prepared with the extracts were subjected to spray drying process using an inlet air temperature (Tin) of 145 °C and evaluating two mass flux (QL) 10 and 15 g/min. Physical characterization of the encapsulated powder was obtained by determining moisture, water activity and moisture gain.
Results demonstrated that the vegetable and seeds studied have 0.5 – 11% of fructans. The lower outlet temperature for the spray drying process was 63°C with QL of 15 g/min, obtaining a final probiotic content of 107 cfu/g. The powders presented good physical properties of water content (2%) and aw (<0.3) and when using the extracts as an encapsulating agent with maltodextrin, smaller moisture gain (3-4 times less) was achieved.
The final results show that natural prebiotics can be used as encapsulating agents in the spray drying process using maltodextrin to assist probiotic growth and be used as functional ingredients in new food product development.
See more of this Group/Topical: Food, Pharmaceutical & Bioengineering Division