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Production of oligosaccharides from coconut meal by subcritical water treatment



Coconut meal, a by-product from coconut milk production, was hydrolysed via subcritical water treatment at various maximum temperatures in the range of 100–300 °C using a batch-type vessel under nonisothermal conditions. The effect of the treatment temperature and time was evaluated using the severity factor (R0) as a parameter. The highest yield of mono- and oligosaccharides (28.3 g/100 g dry coconut meal) was obtained at lnR0 = 10.4 (maximum temperature of 250 °C within the treatment time of 14 min). At higher temperature, degradation of the saccharides was observed and a large quantity of 5-hydroxymethyl-2-furaldehyde was detected. The hydrolysates contained mannose, glucose and manno-oligosaccharides with various degrees of polymerisation. The yield and ratio of saccharide components were affected by variation of the ratio of coconut meal to water used in the subcritical water treatment.