Investigation of Kokumi Substances and Bacteria in Thai Fermented Freshwater Fish (Pla-ra).

A 16S rRNA next-generation sequencing technique was applied to investigate the microbial diversity and liquid chromatography-tandem mass spectrometry was used to identify glutamyl peptide profiles of 10 Thai fermented freshwater fish (Pla-ra) samples. A total of 12 genera of bacteria were able to be detected, with Tetragenococcus spp., Staphylococcus spp., and Lactobacillus spp. dominating. Of the 18 glutamyl peptides analyzed, 17 were found, even though the amounts detected were lower than the taste threshold. Despite this, an increase in mouthfulness sensation, reflecting kokumi activity, was clearly identified in most of the samples, which might be because of a synergistic effect of different sub-threshold compounds present in the samples. In principle component analysis, the relationship between microorganisms and glutamyl peptide generation was observed, especially between Tetragenococcus spp. and Lentibacillus spp. and the generation of γ-Glu-Val-Gly. Correlations between microbial diversity and the generation of taste enhancers were identified in this study.

Metabolic variation in the pulps of two durian cultivars: Unraveling the metabolites that contribute to the flavor.

Durian (Durio zibethinus M.) is a major economic fruit crop in Thailand. In this study, two popular cultivars, namely Chanee and Mon Thong, were collected from three orchards located in eastern Thailand. The pulp metabolome, including 157 annotated metabolites, was explored using capillary electrophoresis-time of flight/mass spectrometry (CE-TOF/MS). Cultivars and harvest years had more impact on metabolite profile separation than cultivation areas. We identified cultivar-dependent metabolite markers related to durian fruit quality traits, such as nutritional value (pyridoxamine), odor (cysteine, leucine), and ripening process (aminocyclopropane carboxylic acid). Interestingly, durian fruit were found to contain high amounts of γ-glutamylcysteine (810.3 ±â€¯257.5 mg/100 g dry weight) and glutathione (158.1 ±â€¯80.4 mg/100 g dry weight), which act as antioxidants and taste enhancers. This metabolite information could be related to consumer preferences and exploited for durian fruit quality improvement.

Spatial variance of physicochemical properties within mangos and the effect of initial ripeness stage on the quality of fresh-cut mangos.

BACKGROUND: This study aimed to assess the spatial variation in physicochemical properties within individual mangos, as well as to investigate the influence of initial ripeness level on physicochemical characteristics of fresh-cut mangos. Individual mangos were evaluated at 12 specific flesh positions in the inner and outer sides. Mango cubes of 1.5 cm prepared from three firmness stages were monitored for changes during 9 days of storage at 5 °C. RESULTS: Mango fruit varied significantly in firmness and color based on spatial position, with the ripening direction from the inner flesh outward and from the stem end to blossom end. Limitations to fresh-cut mango quality were 'desiccation' (dried cut surface) and 'edge or tissue damage' (cut edge damage or brown and bruise-like appearance). Firmer texture and paler yellow of inner flesh were found in less mature mango fruit (P < 0.001). The optimal ripeness stage for fresh-cut mango products was 45 N, based on ease of handling, fresh appearance at the time of purchase and intermediate physicochemical properties (firmness, color and SSC/TA ratio). CONCLUSION: Spatial variance and initial ripeness stage affect fresh-cut mango quality. Therefore, they must be considered by fresh-cut mango processors in order to attain optimal product quality. © 2015 Society of Chemical Industry.

Effectiveness of calcium chloride and calcium lactate on maintenance of textural and sensory qualities of fresh-cut mangos.

UNLABELLED: The effects of calcium chloride (CaCl2 ) and calcium lactate on maintaining textural and sensory quality of fresh-cut "Kent" and "Tommy Atkins" mangos and determination of treatments preferred by consumers were investigated. Mango cubes (1.5 × 1.5 × 1.5 cm) were subjected to different CaCl2 and calcium lactate concentrations (0 M, 0.068 M, 0.136 M, 0.204 M) and dip times (0, 1, 2.5, 5 min). Instrumental quality parameters (firmness, color, soluble solids, titratable acidity) were analyzed periodically during 9 d of storage at 5 °C. Tommy Atkins mango cubes became more orange, but also had more browning than Kent mango cubes during storage at 5 °C. Firmness retention during storage was greater with mangos cubes treated with CaCl2 than with calcium lactate, therefore we focused our instrumental analysis only on CaCl2 -treated cubes. The firmness of Tommy Atkins mango cubes was higher than Kent. Soluble solids content (SSC), titratable acidity (TA), and SSC/TA were higher in fresh-cut Kent mango cubes. Mangos treated with CaCl2 showed retarded softening during storage, and the retardation was greater at higher calcium concentrations. A consumer test was conducted to cluster consumers based on mango preference in order to correlate consumer liking and calcium treatments, as well as to uncover consumer intentions for in-store fresh-cut mango purchases. Treatment at 10 °C with 0.136 M CaCl2 for 2.5 min for Tommy Atkins mangos and 1 min for Kent mangos was effective in retaining firmness during storage at 5 °C and was also not disliked by consumers. A cluster analysis divided consumers into 2 preference groups, with Kent mangos significantly preferred over Tommy Atkins. PRACTICAL APPLICATION: Fresh-cut mangos often develop tissue softening and discoloration during storage. Short dips (1 to 3 min) in either CaCl2 or calcium lactate effectively improve fresh-cut mango firmness and color retention after cutting. Mango samples treated with CaCl2 had higher liking scores compared to those treated with calcium lactate. "Kent" mango variety is more suitable than "Tommy Atkins" for fresh-cut processing in terms of less tissue browning and higher consumer liking.

Effects of 1-methylcyclopropene and hot water quarantine treatment on quality of "Keitt" mangos.

The optimal 1-methylcyclopropene (1-MCP) treatment to slow ripening of whole "Keitt" mangos, either alone or in combination with hot water treatment (HWT) (prior to or post 1-MCP) was identified. USDA-APHIS mandates that HWT can be used for control of fruit flies, but this may affect fruit response to 1-MCP. Mangos were evaluated by repeated measurement of nondestructive firmness, peel color, and ethylene production on the same mango fruits during 2 wk of ripening at 20 °C after treatment. The magnitude of ethylene production increased as a result of both 1-MCP and HWT. With softer mangos (65 N), treatment with 1-MCP alone delayed fruit softening and extended the number of days to full-ripeness (25 N) from 5 d in untreated fruit to 11 d. For these riper fruit, application of 1-MCP prior to HWT extended the days to full-ripeness to 9 d compared with 7 d when 1-MCP was applied after HWT. With firmer mangos (80 N), 1-MCP treatments alone prolonged the days to full-ripeness to 13 d as compared to 11 d for the untreated fruit. There was no significant concentration effect on firmness retention among 1-MCP treatments (0.5, 1.0, or 10.0 µL/L). HWT resulted in a faster rate of fruit softening, taking only 7 d to reach full-ripeness. Combining 1-MCP with HWT reduced the rate of softening compared to HWT alone, resulting in 9 to 11 d to full-ripeness. Application of 1-MCP before HWT showed a greater ability to reduce the rate of fruit softening compared with 1-MCP treatment after HWT.