Deterioration of fresh and stale cane juice at high ambient temperature in relation to expression of invertases and the growth of Leuconostoc sp

In sub tropical India, sucrose losses from sugarcane after harvest is enormous resulting in low sugar recovery. Sugarcane variety CoSe 92423 was selected to assess the post-harvest quality losses during the late-milling period when the ambient temperature was around 40–42° C. The juice was extracted from fresh harvested and stale cane (72 hour after harvest), and quality parameters and acid invertase activity was determined at certain intervals in juice, incubated at room temperature. The loss of commercial cane sugar (CCS) in fresh cane juice after 20 hours of extraction was 30.12%, whereas in stale cane juice CCS loss was 84.68% in comparison to initial value. Reducing sugars in fresh cane juice increased by 36.71 folds/100Brix whereas in stale cane juice, it increased by 214.16 folds/100 Brix, after 20 hours incubation. The activity of acid invertase in the juice of fresh and stale cane showed a remarkable difference which was nearly six fold higher in stale cane at the time of juice extraction. This difference in the acid invertase activity of fresh and stale cane was perceptible till 20 hours and one of the major factors responsible for the decline in sucrose content in harvested cane. Selective medium was used for detection of growth of an important polysaccharide producing bacterial strain Leuconostoc in harvested fresh and stale (72 hr) cane juice. It was found that the growth of this microorganism almost doubles in stale cane juice (370 cfu/100 ol) in comparison to fresh cane juice (177 cfu/100 ol) after 20 hours of extraction. The addition of a quaternary ammonium compound based formulation recorded appreciable improvement in quality parameters and inhibition of acid invertase activity. The formulation also proved to be promising in inhibiting the growth rate of Leuconostoc bacterium. The impact of stale cane on quality parameters vis-à-vis sucrose recovery during the late crushing season is described.