In this study, water activity in microwave-puffed shrimp
chips was not decreased by calcium salt fortification, as it was
designed to eliminate the possibility of acrylamide formation
arising from the reaction between reducing sugars and
nitrogen-containing compounds. Water activity in deep-fried
and microwave-puffed shrimp chips in the control sample
was 0.49 and 0.35, respectively (Fig. 1). Reduction of water
activity was only detected in deep-fried puffed shrimp chips
fortified with calcium citrate. From a food safety prospective,
the levels of water activity in all control and fortified chips
were low enough for either deep-frying or microwave puffing.
Compared with the control sample, the addition of calcium
salts at a concentration higher than 0.1% significantly
increased the ash content of shrimp chips (p < 0.05). Our results
suggest that the interaction between calcium cations
and reducing sugars in shrimp chips was the main factor
affecting pH in shrimp chips.