Abstract:
The objectives of this research were firstly to develop the production process of instant Centalla asiatica (Linn.) Urban (Buo-Bok) drink by studying the effect of pH of fresh Buo-Bok juice (pH 5.0, 6.0-6.4 and 7.0) on the total chlorophyll and color (L and hue value) of Buo-Bok powder. Secondly, the optimum spray drying condition was determined by varying the inlet air temperature (135-175℃), quantity of cyclodextrin (0.33-0.99 gram per 100 ml of fresh Buo-Bok juice), and flow rate of fresh Buo-Bok juice (9.67-33.33 ml per min.) using Bo-Behnken design. Thirdly, the optimum ratio of Buo-Bok powder to sucrose (12.24-3.76 gram to 87.76-96.24 gram) and ratio of Buo-Bok mix to warm water (50 ℃) 2.94-17.07 gram to 100 ml) were studied using orthogonal rotatable desing. Fourthly, the agglomeration process was studied by varying the ratio of fresh Buo-Bok juice to Buo-Bok mix (1:15, 1:20 and 1:25 ml/gram). Lastly the shelf-life of instant Buo-Bok drink packaged in PET/metallized PET/PE/EAA was studied at the accelerated condition (35° and 45℃). The results showed that the unadjusted pH Buo-Bok juice had the highest amount of total chlorophyll. The unadjusted pH Buo-Bok juice and that treated pH 7.0 with Ca(OH)2 solution had higher L values but lower hue values than that treated to pH 5.0 with ZnSO4 solution. The optimum spray drying conditions of fresh unadjusted pH Buo-Bok juice were : inlet air temperature 150℃, the amount of cyclodextrin 0.665 gram per the juice 100 ml, and the flow rate 12.77 ml per min. The ratio of Buo-Bok powder 7.07 gram per sucrose 92.93 gram gave the best Buo-Bok mix and the ratio of Buo-Bok mix 6.85 gram per warm water 100ml gave the overall acceptability of product in the range of very much to extremely acceptable. The optimum ratio of fresh Buo-Bok juice to Buo-Bok mix for agglomeration process was 1 ml per 25 gram which gave the solubility measured as total insoluble solid of 1.78% and the dispersibility measured as OD at 642.5 nm of 0.15. The moisture content of the product was 1.67% which was lower than the reported critical moisture content for instant drink. The instant Buo-Bok had shelf-life at 35℃ of 10 weeks and 4 weeks at 45℃, and the cost of the product was 3.15 Baht per pack (12.5 gram).