Use of dried Som-Khaek as sour flavouring in Tom-Yum cubes

Tom-Yum soup is one of the most popular dishes in Thai cuisine. Lime juice is a very important ingredient because it gives sour flavouring which is the essence of the soup. Using lime juice has, however, some drawbacks because lime is a seasonal fruit which is scare and very expensive in some seasons. This study suggested the use of Som-Khaek as an alternative sour flavouring. Som-Khaek is a local fruit containing hydroxy citric acid which gives sour flavour. Som-Khaek is available and cheaper than lime. When dried, it can be kept for years. Using dried Som-Kheak to make Tom-Yum cubes will, therefore, make optimum use and add value. This study was conducted to investigate the use of dried Som-Khaek as sour flavouring in Tom-Yum cubes. Som-Khaek contained 8.44 percent of moisture content, 2.07 percent of protein, 1.62 percent of fat, 1.47 percent of ash, 1.92 percent of crude fiber and 84.48 percent of carbohydrate. The optimum formula of Tom-Yum cube, produced under Ratio Profile Test, comprises Som-Khaek 13.99 percent, lemon grass 8.95 percent, bergamot leaves 3.49 percent, red onions 7.90 percent, coriander root 2.73 percent, sugar 17.48 percent, salt 22.73 percent, chilli 10.49 percent and glycerine 12.24 percent. In preparing Tom-Yum cube, the dry ingredients were blended together then glycerine was added. After that, the mixture was sieved through stainless steel screen, put in a 2.70*3.30*5.00 cm mould and pressed at 17,000 lb./square inch in a hydraulic press for 3 min. The finished product weighed 14.30 g/cube, L=48.50, a=9.70, b=25.45 and was brown in color. The aw of Tom-Yum was 0.31 and its shear strength was 49.80 Newton. The Tom-Yum cube contained 20.66 percent moisture content, 3.10 percent protein, 1.72 percent fat, 7.54 percent ash, 2.42 percent crude fiber and 64.65 percent carbohydrate. The product was microbiologically safe with 40 colony of microbial count and less than 10 colony of yeast and molds per gram of sample product. The study also included a comparative test between Tom-Yum soup using Som-Khaek powder (2 g) citric (1.20 g) and lime juice (10 ml). The tasters accepted and preferred the soup seasoned by lime juice, Som-Khaek powder and citric acid respectively. Shelf-life of the Tom-Yum cube wrapped in aluminum foil and laminated with polyethylene was no more than 6 weeks if stored at room temperature.