Freeze drying technique for microencapsulation of Garcinia fruit extract and its effect on bread quality

Microencapsulation is an enduring technology for protection and controlled release of food ingredients. The Garcinia cowa fruit rinds are rich source of (−)-hydroxycitric acid (HCA), which is reported to have various health benefits. But, HCA is hygroscopic in nature and thermally sensitive. Hence, G. cowa fruit extract was microencapsulated using three different wall materials such as whey protein isolate (WPI), maltodextrin (MD) and combination of whey protein isolate and maltodextrin (WPI + MD in 1:1 ratio) by freeze drying at 30% concentration. The microencapsulated powders were evaluated for their impact on bread quality and free HCA concentration. The microcapsules exhibited wider particle size range of 15–100 μm and HPLC analysis showed that all the three encapsulates yielded higher free (above 85%) and net (above 90%) HCA recovery. Moreover, bread with WPI encapsulates exhibited higher volume, softer crumb texture, desirable colour and sensory attributes and had higher free HCA concentration. This indicated that WPI has excellent encapsulation efficiency than other two wall materials during bread baking.     

Synthesis and Polymerization of Bismaleimide Derived from 5(6)-amino-1(4′-aminophenyl)-1,3,3′-trimethyl indane

The acid-catalyzed dimerization of α-methyl styrene led to the formation of trimethyl phenyl indane, which on nitration followed by reduction using hydrazine hydrate gave 5(6)-amino-1(4′-aminophenyl)-1,3,3′-trimethyl indane. This aromatic diamine was used to synthesize bismaleamic acid and imidized to yield bismaleimide. The bismaleamic acid was converted to prepolymer directly by imidizing it in refluxing toluene. All the materials synthesized were characterized using FTIR, ¹H and ¹³C NMR. The direct inlet mass spectral characterizations were carried out for bismaleamic acid, bismaleimide and bismaleimide prepolymer. The fragmentation pattern was discussed in detail and the structure proposed was confirmed. The thermogravimetric studies were done for all the materials and kinetic parameters (energy of activation and frequency factor) were calculated using Dharwadkar and Kharkhanavala method. The structural changes occurring in the thermally polymerized bismaleimide and bismaleimide prepolymer were discussed.     

Loss of solubility of α-lactalbumin and β-lactoglobulin during the spray drying of whey proteins

A reversed phase HPLC technique has been applied to measure the loss of solubility (at pH 4.6) of α-lactalbumin and β-lactoglobulin resulting from the spray drying of whey protein isolate solution. Spray drying was performed in a pilot-scale co-current spray dryer with different feed concentrations (20-40% w/v) and outlet temperatures (60-120 °C). The study reveals that the solubility of both α-lactalbumin and β-lactoglobulin was not significantly affected at low outlet gas temperatures (60-80 °C), but was strongly affected (up to 40%) at high temperatures (100-120 °C). Significantly higher losses in solubility were observed for β-lactoglobulin compared to α-lactalbumin. Increasing the feed concentration at higher outlet temperatures also caused noticeable increases in insolubility. The reversed phase HPLC results were consistent with those from total protein nitrogen content (Kjeldhal) analyses.     

A comparative study on conventional and microwave-assisted extraction for microencapsulation of Garcinia fruit extract

(?)-Hydroxycitric acid (HCA) is the principal acid present in the fruit rinds of certain species of Garcinia and is reported to have various health benefits. However, HCA is highly hygroscopic in nature and becomes lactonised during evaporation and drying. To reduce the lactonisation of HCA, Garcinia cowa fruit extract was obtained through two different extraction techniques, autoclave and microwave-assisted extractions, and was then microencapsulated using whey protein isolate (WPI) and denatured whey protein isolate (DWPI) with a 1:1 wall-to-core ratio using a spray drying technique. The microwave-assisted extracts encapsulated with WPI and DWPI had higher free HCA and net HCA recovery than the autoclaved extract encapsulated with similar wall materials. Furthermore, the microwave-assisted extracts and the associated encapsulated samples had higher antioxidant activity than their counterparts. The encapsulation of the microwave-assisted extracts with both wall materials had little variations in their free (55.04 and 54.58% for WPI and DWPI, respectively) and net HCA recovery (84 and 82%) and antioxidant activity (13.3 and 13.6%), which signified a smaller influence of the wall materials. These results indicated that microwave-assisted extraction had a higher extraction efficiency, encapsulation efficiency and antioxidant activity with both wall materials.