First the Japanese did it with volcanic ash. Then the Italians, with clay pots. Now Boston entrepreneurs Richard Cole and Max Greenbaum are doing it with plastic bags that breathe. "It" is slowing down the respiratory rate of vegetables, thereby considerably extending their crispness and crunch. "In tests, we've had lettuce last up to 30 days," notes Cole. The two packaging veterans have spent four years and $200,000 refining the Fresh Pak, a permeable sack made from polyethylene film combined with a natural clay additive, which enables the spoilage-inducing gas ethylene to escape from the bag's atmosphere. Growers, whose interests lean more toward repeat sales than produce preservation, have greeted Fresh Pak with mixed responses. Trials with supermarket chains and some McDonald's kitchens are currently under way, but Fresh Pak is concentrating the bulk of its efforts on the consumer market. A 10-pack of bags retails for $2.95. Cole expects to break even within the next six months and projects sales of $500,000 for 1993.

-- Alessandra Bianchi