Effect of Filtering Ozone-Polluted Dryer Air Through Activated Charcoal on the Flavor of Foam Spray-Dried Whole Milk

Abstract

To determine whether the flavor of dried milk manufactured with ozone-polluted air could be improved by filtering the air through activated charcoal, a series of foam spray-dried whole milks were manufactured using, alternately in each experiment, standard cellulose dust filters and activated charcoal filters in the dryer air inlet. Using cellulose filters, ozone levels of air entering the dryer were 4–17 parts per billion (average 8 ppb) and powder flavor 0.6–4.0 flavor points (average 2.0 points on a 10-point scale) lower than their parent concentrates. Using charcoal filters, ozone levels of air entering the dryer were zero, and powder flavor varied from 0.2 point higher to 0.7 point lower (average 0.1 point lower) than concentrates. Ozone levels as low as 6 parts per billion,if added to charcoal-purified air, had a definitely damaging effect on the powder's flavor. Powder manufactured in ozone-free air, and cooled before exposure, retained its high flavor quality during moderate subsequent exposure to polluted air. © 1969, American Dairy Science Association. All rights reserved.