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Investigations were carried out to determine changes in physicochemical and microbial qualities of oven-dried, sun-dried and freeze-dried Ipomoea aquatica Forsk., a popular leafy vegetable (known as kangkung). Sun drying showed low retention of fat and fiber with insignificant changes in protein content, whereas, freeze-dried samples showed high retention of ascorbic acid. Results of 2,2diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay showed higher inhibition in oven-dried samples, followed by freeze-dried and sun-dried samples. In addition, freeze-dried samples retained chlorophyll better among the three dried samples. Total bacteria, yeast and mold counts and Escherichia coli count in kangkung showed significant decrease on drying. PRACTICAL APPLICATIONDrying is an age-old technique used to preserve food. Results of this work can be beneficial to consumers who might be interested in being acquainted with the retention of the overall qualities of dried leafy vegetables. Results obtained are expected to promote the commercial application of dried kangkung as a raw ingredient and develop value-added healthy food products such as crackers and refreshing healthy drink mixes.

In this study, nutritional qualities and functional properties of underutilized Beko pod flour were investigated. Results revealed the presence of high amounts of crude protein, ash, crude fiber, carbohydrates (8.45, 4.11, 18.89 and 67.49 g/100 g, respectively) and total dietary fibers (42.45%). Beko pod flour contained cysteine and glutamic acid (15.30 and 10.57 g/100 g crude protein, respectively) as predominant amino acids, with appreciable amounts of total unsaturated fatty acids. In addition, pod flour had acceptable functional properties, which are envisaged to be useful in developing new food products. In addition, Fourier transform infrared spectra showed presence of amines, amides, carboxylic acids, amino acids and aromatic compounds. PRACTICAL APPLICATIONSThis study provides vital database on the nutritional potential of Beko pods flour, which can be exploited in food bio-fortification, or as basic raw material for the development of new functional food ingredients.

This study investigates the growth and survival of Zygosaccharomyces rouxii (a xerotolerant yeast) in the glycerol-based intermediate moisture food (IMF) pineapple model systems (0.87 aw/pH 4.1 GLY/CPB/BM and 0.87 aw/pH 4.5 GLY/CPB/ BM) containing various levels of chemical preservatives (sodium benzoate, potassium metabisulphite and potassium sorbate) used singly or in combination. Comparing the two different levels used singly, the three preservatives were more effective in inhibiting yeast growth at a higher 0.1% (w/w) than at a lower 0.01% (w/w) level of the preservative, with potassium metabisulphite showing most inhibitory effect at 0.1% (w/w) level. When the combinations of two to three preservatives at 0.01% (w/w) level were evaluated, a synergistic growth inhibitory effect was achieved. Combination of three preservatives was more effective compared to a combination of any of the two preservatives. At different pH values, preservatives used singly or in combination were shown to be more effective in inhibiting growth at lower pH value of 4.1 than at a higher pH value of 4.5. Taste evaluation of six formulated acidified 0.87 aw/pH 3.7 glycerol-based IMF pineapple products showed all formulations to be acceptable. However, microbial challenge studies showed that of all the six taste-acceptable glycerol-based IMF pineapple products, only the product that contained 0.1 % (w/w) potassium metabisulphite was shelf-stable up to 6 months of storage at 30C and may be commercially viable. PRACTICAL APPLICATIONSThe results of this study will benefit the food industry wherein preservation of intermediate moisture pineapple-based products or other intermediate moisture products is required to overcome contamination problems, especially from xerotolerant yeasts.

This study demonstrated injury of a 2-day-old stressed Zygosaccharomyces rouxii YSa40 (Xerotolerant yeast) cells in 0.64 water activity (aw)/pH 3.5 glycerol (GLY)/ CPB stress system. The effects of metabolic inhibitors on repair of the low aw injury were also investigated by resuscitating the low aw injured cells over a time period of 24 h in a suitably designed 0.87 aw/pH 3.5 GLY and sucrose (SUC)/ citrate phosphate buffer (CPB) liquid holding (LH) system. On use of appropriate inhibitory concentrations of metabolic inhibitors, repair processes in low aw-injured populations involved cell membrane and cell wall synthesis, protein and DNA synthesis and adenosine triphosphate (ATP) from glycolysis, but without oxidative phosphorylation. During 24 h of LH period, ATP was vital to maintain the cell viability of the surviving population on 0.94 aw/pH 3.5 sugars/ basal medium agar (lactic acid); while allowing its injured population to repair at low aw injury in the LH system. This oxidative phosphorylation pathway can provide insight into various mechanisms of repair in low aw-injured yeast cells.