RESUMEN
Antidesma thwaitesianum Müll. Arg. or Mao is well-known in Thailand for its use in soft drinks and wine. This study investigated the potential of its fruit juice as a food preservative based on its antimicrobial activity against food-borne pathogens and spoilage. The fruit juice had antibacterial activity against Bacillus cereus TISTR1527, Staphylococcus aureus TISTR2329, Listeria monocytogenes DMST17303, Pseudomonas aeruginosa TISTR357, Salmonella Typhimurium DMST562, and Escherichia coli TISTR074. The minimum inhibitory concentration ranged from 25 to 100 mg/ml. Of significance was that the juice had excellent antifungal activities against Aspergillus flavus TISTR3135 and Penicillium digitatum ATCC10030. Furthermore, the fruit juice increased the lag time of spore germination of P. digitatum. Analysis of the phytochemical contents of the juice showed that the total phenolic and flavonoid contents were 20.07 mg GAE/g and 3.57 mg QE/g, respectively. In antioxidant activity assay, the juice exhibited moderate DPPH and ABTS+ radical scavenging and ferric-reducing activities. The addition of 5% fruit juice extended the microbial shelf life of chiffon cake. The treated chiffon cake had a shelf-life of 7 days, compared to 3 days for the untreated control. These results support the possible use of Mao fruit juice as an antimicrobial agent and a natural food preservative.
RESUMEN
The alteration of the profile of volatiles of canned coconut milk was monitored during storage at ambient temperature. Canned coconut milk was thermally processed (121 °C for 5 min), and then stored at ambient temperature (32 to 35 °C) for 6 mo. Volatile compounds were assessed monthly using direct solvent extraction (diethyl ether), followed by high-vacuum distillation and gas chromatography-mass spectrometry analysis. Six groups of compounds consisting of alcohols, aldehydes, ketones, acids, esters, lactones, and others were identified. Two stages of major changes in profile of volatiles were observed. The 1st occurred after 2 mo as indicated by a high abundance of alcohols, acids, and lactones. The 2nd was observed after 5 mo and corresponded to a large increase in lactones, short-chain free fatty acids, 3-methyl-2(5H)-furanone, and phenol. Acetic and butyric acids observed after 5 mo could contribute to the potential of off-odor development in the product as indicated by their high odor activity values. Lactones increased approximately 10-fold. Identification of 3-methyl-2(5H)-furanone indicated that Maillard reaction had occurred in conjunction with the development of a coconut, toffee-like, and caramel odor.