Modification of starch using low pressure radio frequency air plasma

Cold plasma is one of the emerging nonthermal food processing technologies recently drawn interest as a chemical-free biopolymer modification method. In the present study, two starches (corn and tapioca) were exposed to low pressure radio frequency plasma at 40 W and 60 W for 10 and 20 min. The effect of air plasma treatment on the starch properties was determined by measuring amylose content, swelling power, powder flowability properties, gelatinization temperatures and pasting properties. The amylose content of corn and tapioca starches was observed to decreased and increased respectively. Increase in water binding capacity and swelling power of both starches. The results of pH showed partial oxidation of starches as evident from the decrease in pH. Rapid visco analyzer showed an increase in final viscosities after the plasma treatment. The increase in viscosities is the result of higher amounts of leach out of particles from the starch granules. Plasma treated corn starches exhibited lower peak temperatures and enthalpies whereas it increased in tapioca starches. X-ray diffractogram revealed an A-type pattern of both starches and plasma treatment did not show any significant effect on the crystallanity pattern. Cold plasma offers a unique route for starch modification without affecting its bulk properties.