Thick juice degradation during storage

A study of the changes occurring in thick juice during storage in large tanks for periods of up to 200 days is reported. Additional laboratory work to investigate the effect of storage parameters such as pH value, dry substance content and temperature is described. The work focuses on the occasional rapid fall in pH value which can occur after a long period of satisfactory storage. The cause of the pH fall was found to be the production of L-lactic acid, formed from sucrose as a result of bacterial activity. High juice pH value, high dry substance content and low initial bacterial count were found to allow longer storage without juice degradation but did not eliminate the possibility of bacterial growth. Temperatures below 10 °C prevented bacterial growth over a storage period of one year even when bacteria were initially present.