Stability Studies of Microencapsulated Anthocyanins of Roselle (Hibiscus Sabdariffa L) In Native Starch and Its Potential Application in Jam Production

Abstract

The significance of natural food colorants such as Roselle anthocyanins had been known for decades. However their stability in and out of food systems is still a challenge. This work was aimed at mitigating this phenomenon. Various solvent extracted, microencapsulated in native corn starch and freeze dried samples[ethanol acidified with 1% citric acid (FDMEE), 2% citric acid solution (FDMCE) as well as distilled water (FDMWE) ] were prepared using standard techniques. These were kept under room temperature conditions for eight weeks and physicochemical evaluations conducted periodically. Some of these were utilized (1% inclusion) in the production of jam and evaluated by a 30 man sensory panel. Colour intensity indicated by Chroma Values (a*) of microencapsulated samples were: FDMEE (2.20 + 0.01), FDMCE (3.05 + 0.02) and FDMWE (1.98 + 0.00). Analysis of total soluble solids (0Brix), titratable acidity (% citric acid) and anthocyanins (mg/100g) in this order gave the following FDMEE (5.1+0.00, 15.35+0.2, 968.53+0.26); FDMCE (5.5+0.00, 18.41+0.16, 1217.13); FDMWE (4.8 + 0.00, 13.93 + 0.14, 882.51 + 0.44). These values were significantly different from their non-encapsulated equivalents (p<0.05). Sensory scores for jam containing microencapsulated extract compared favourably with the non-encapsulated inclusive samples. Freeze dried microencapsulated anthocyanins in native corn starch is colour stable and valuable in the production of acceptable jam.