Influence of clarifying agents on the quality of pasteurised palmyra palm sap (Borassus flabellifer Linn.)

The effects of clarifying agents, including bentonite, polyvinylpolypyrrolidone (PVPP), gelatin and chitosan, on the quality attributes of pasteurised palmyra palm sap were evaluated. After clarification and pasteurisation, the lowest polyphenol oxidase (PPO) and invertase activities were detected in the sample clarified with bentonite. PVPP and gelatine were found to be the most effective for removing polyphenol content. In addition, the sample treated with chitosan had the highest transmittance values. However, the sucrose, glucose and fructose contents were not affected by clarification. During storage, the PPO activity, invertase activity, polyphenol content and sucrose level decreased, while the fructose and glucose levels increased with the storage times. According to the Thai Community Product Standard, all pasteurised samples treated with a clarifying agent were acceptable for up to 25 days, whereas the nonclarified sample was spoiled because of the microbial loads. Thus, the clarification process prior to pasteurisation was able to improve the quality and microbiological shelf life of the pasteurised palmyra palm sap for at least 25 days.