Texture improvement of fresh and frozen mangoes with pectin methylesterase and calcium infusion.

BACKGROUND: A major problem of mango products is texture loss. The effect of commercial pectin methylesterase (PME) and calcium infusion on improvement of the texture of both fresh and frozen-thawed mango cubes was investigated in the present study. RESULTS: The weight gain and moisture content of mango samples were greater at relatively high vacuum level (10 kPa). The PME activity of samples infused with PME and calcium at 10 kPa increased fourfold in comparison with that of control and water-infused samples. The combined effect of PME and calcium was found to improve the texture and microstructure of both fresh and frozen-thawed mangoes. Fresh mangoes infused with PME and calcium at 10 kPa showed significantly higher firmness than control fresh samples. Frozen-thawed mangoes infused with PME and calcium at 50 kPa and atmospheric pressure had superior texture and microstructure in comparison with control frozen-thawed samples. CONCLUSION: The results of the present analysis allow for a better appreciation of the role of PME, calcium and appropriate infusion conditions in improving the texture of both fresh and frozen-thawed mangoes.

Antidesma thwaitesianum Müll. Arg. Fruit Juice, Its Phytochemical Contents, Antimicrobial Activity, and Application in Chiffon Cake.

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.