Microencapsulation of water-soluble isoflavone and physico-chemical property in milk

Encapsulation of isoflavone with milk, maltodextrin and gum acacia improves its stability

This study was carried out for extraction of soy isoflavones and entrapment of the isoflavones so obtained into whole milk via encapsulation techniques. Three different solvent (ethanol, methanol and acetonitrile) were used for the extraction of isoflavone using three stage of extraction. The extracted isoflavone was encapsulated into 200 ml of whole milk by spray drying using different concentrations of gum acacia (4, 6 and 8% w/v) and 10% w/v maltodextrin DE 18. The ratio between cores to coating materials was 1:10. Though acetonitrile extracted higher amount of isoflavone, ethanol was selected for subsequent studies of extraction of isoflavone, as per the legislations regarding use of Food-grade solvents. There was no significant difference (p > 0.5) among all three samples 4% gum acacia+10% maltodextrin (A), 6% gum acacia+10% maltodextrin (B) and 8% gum acacia+10% maltodextrin (C) in terms of moisture content and hygroscopicity. However, insolubility index showed that sample A possessed a higher solubility index. Encapsulation techniques suggested that sample A showed higher encapsulation efficiency than others. Statistical analysis suggested that there was no significant difference among samples A, B and C during storage at 4°C for the time period (30 days) studied, in terms of isoflavone retention rate. However, samples stored at 25 and 37°C showed significant difference in the retention rate. Among all the three samples, sample B showed significantly lower isoflavone degradation rate of 3.80, 4.07 and 4.70 × 10-3/day at 4, 25 and 37°C, respectively. The highest amount of isoflavone degradation was observed at 37°C. Results indicate that isoflavone can be encapsulated using a combination of gum acacia either 4 or 6% w/v and 10% maltodextrin along with milk proteins at 4°C for longer shelf life.

Encapsulation of grape seed extract phenolics using whey protein concentrate, maltodextrin and gum arabica blends

Grape seed extract (GSE) contain phenolic compounds that decrease the proclivity to various chronic diseases such as several types of cancer and cardiovascular diseases. The objective of the present study was to investigate the encapsulation of GSE polyphenols and their characterization. For this study, whey protein concentrate (WPC), maltodextrin (MD) and gum arabic (GA) were evaluated as encapsulating materials. For the preparation of stable microcapsules different WPC:MD/GA (5:0, 4:1, 3:2 and 0:5) ratios were assessed using ultrasonication for different time periods (20-40 min) followed by freeze drying. Encapsulation efficiency, antioxidant activity, particle size, surface morphology and release mechanism were determined. The GSE microcapsules coated with WPC:MD/GA ratio of 4:1 and 3:2 with core to coat ratio of 1:5 and prepared by sonication for 30 min were found to have highest encapsulation efficiency (87.90-91.13%) and the smallest particle size with maximum retention of antioxidant activity. Under optimized conditions, the low level release (43-49%) of phenolic compounds resulted under simulated gastric condition and significantly (p < 0.05) increased (88-92%) under simulated intestinal condition. Thus the results indicated blending of MD or GA with WPC improved the microencapsulation of GSE.

Effect of microencapsulation on concentration of isoflavones during simulated in vitro digestion of isotonic drink

Isotonic drinks, fortified with microencapsulated maltodextrin and inulin isoflavone extract, were evaluated by organoleptic assessment and color measurement on the CIE L*a*b scale, then they were subjected to in vitro digestion. Changes of concentrations of isoflavones released during digestion of drinks and their ability to neutralize free radicals (ABTS) were determined. The effect of microencapsulation and storage on isoflavone content in isotonic drinks was also evaluated. In the organoleptic evaluation, beverages without additives and beverages fortified with microencapsulated extract were evaluated as better than a beverage with pure extract. Microencapsulation largely eliminated the unpleasant taste and odor of isoflavones and masked their color. Before digestion, isotonic drinks contained 29.07-43.17 μg of isoflavones in 1 ml. Microencapsulated isoflavones were released gradually during simulated digestion. The highest recovery of these compounds was observed for glycoside and malonylate derivatives of daidzein. Daidzin and genistin with encapsulation showed bioavailability of 0.02%-0.07%. The use of inulin as a carrier increased the stability of microcapsules during the storage of isotonic beverages. Microencapsulated of isoflavones from soybeans can increase the health benefits of conventional beverages available on the market.

Microencapsulation of bioactives for food applications

The potential of microencapsulation to protect bioactive compounds ensuring bioavailability maintenance is proved but requires further studies on its applicability and incentives by regulatory agencies.

Application of microencapsulated isoflavone into milk

This study was designed to develop a microencapsulated, water-soluble isoflavone for application into milk and to examine the hypocholesterolemic effect of such a milk product in a rat diet. The coating material was medium-chain triglyceride (MCT) and the core material was water-soluble isoflavone. The microencapsulation efficiency was 70.2% when the ratio (w/w) of coating material to core material was 15:1. The isoflavone release from the microcapsules was 8% after 3-day storage at 40 degrees C. In in vitro study, 4.0-9.3% of water-soluble isoflavone in simulated gastric fluid was released in the pH range of 2 to 5 after 60 min incubation; however, in simulated intestinal fluid at pH 8, 87.6% of isoflavone was released from the capsules after 40 min incubation time. In sensory analysis, the scores of bitterness, astringency, and off-taste in the encapsulated isoflavone-added milk were slightly, but not significantly, different from those in uncapsulated, isoflavone-added milk. In blood analysis, total cholesterol was significantly decreased in the isoflavone-added group compared with that in the control after 6-week feeding. Therefore, this study confirmed the acceptability of MCT as a coating material in the microencapsulation of water-soluble isoflavone for application into milk, although a slight adverse effect was found in terms of sensory attributes. In addition, blood total cholesterol was lowered in rats which had been fed a cholesterol-reduced and microencapsulated, isoflavone-added milk for 6 weeks.