Processing of batuan [Garcinia binucao (Blanco) Choisy] fruit into different forms of souring agents

The fruits of batuan were processed into different forms of souring agents, namely: frozen pasteurized fruits, puree, powdered fruit, and dried whole fruits. Frozen fruits served as the control treatment. The souring agents were found highly acidic (pH ranging from 1.91 to 2.44), with varied total soluble solids (0.8 to 5.13 deg Brix) and moisture content (9.91% to 97.25%). The organic acid profile of the prepared souring agents was analyzed using reversed-phase HPLC coupled with UV detector. It was shown that the dominating acids in all of the souring agents was malic acid, followed by ascorbic acid, and then citric acid, while oxalic acid was below the detection level. The powdered batuan fruits had the highest levels of all acids. Generally, the souring agents which utilized only the pulp of the fruit and undergone dehydration had higher acid contents as compared to those which utilized the whole fruit. In addition, those which undergone pasteurization showed decreased in the level of acids. The profile of the target sugars was established using HPLC coupled with refractive index (RI) detector. Fructose and glucose were observed in all of the souring agents, except in batuan puree. Sucrose, on the other hand, was detected in fresh and frozen samples only. The amount of sugars generally decreased after processing. When compared to broths prepared using tamarind and calamansi extract, sensory evaluation revealed that the different souring agents were not significantly different in terms of aroma, typical sinigang flavor, and sweetness. In terms of sourness, broth prepared using frozen fruits and dried whole fruits were not significantly different from the broth prepared using calamansi extract, while the broths prepared using the frozen fruits and batuan powder were not significantly different from the broth prepared using tamarind extract.