Development and evaluation of an ultraviolet radiation assisted with ohmic heating system for preservation of pineapple juice

Abstract

Ultraviolet (UV) radiation is one such non-thermal processing alternative that has been shown to be effective against many types of foodborne pathogens. But there is a limitation of practical application of UV to disinfect liquid food products due to low penetration depth. Ohmic heating (OH), another promising technology, has been widely applied in food processes. This generates heat immediately in the food product, creating a rapid and uniform heating that reduces thermal abuse, as opposed to conventional thermal processing methods. Often times, ohmic heating cause heat-sensitive nutrients within food to be deteriorated by excessive current flow. These advanced technologies could contribute to shorten processing times, energy savings, and highly balanced safe food; however, they alone still cannot guarantee food safety without damaging the food’s quality. Therefore, a new concept to combine ultraviolet and ohmic heating has been extensively evaluated. This combination technology would optimize each of the individual technology’s strengths and reduce each of their individual weaknesses. The present study envisages development of a UV radiation assisted with ohmic heating system for pineapple juice and evaluation of the developed system in retaining the quality characteristics and microbial safety. In this study, a dual cylindrical ohmic and ultraviolet treatment combination continuous flow chambers was designed and fabricated to pasteurize the pineapple juice. UV treatment 800, 1200 and 1600 mJ/cm 2 . Ohmic treatment until the sample temperature reached 50°C, 55°C and 60°C; and ohmic heating combined with UV treatment as the temperature rose to 50 °C, 55 °C, and 60 °C along with 800, 1200 and 1600 mJ/cm 2 dosages. Combined ohmic heating at 50 °C and UV treatment of 1200 mJ/cm 2 were found to be superior based on biochemical, microbiological and organoleptical characteristics. Storage study of best sample revealed that could give a shelf life of 25 days under a refrigeration temperature at 4 °C retaining its biochemical characteristics while keeping the microbial level safe.