Thermal sensitivity of Neosartorya fischeri ascospores in regular and reduced-sugar grape jelly

Abstract

A study was conducted to determine the thermal sensitivity of Neosartorya fischeri ascospores in regular (standard) and reduced-sugar formulas of Concord grape jelly. Ascospores were inactivated more rapidly by heating in the reduced-sugar formula than in the regular formula. Protection against inactivation in the regular formula may be due to its having a higher pH (3.27) than the pH (3.14) of the reduced-sugar formula. The lower a(w) (0.78) of the regular jelly formula compared to that of the reduced-sugar formula (a(w), 0.82) would also protect against thermal inactivation. These results demonstrate the need to consider the efficacy of thermal processing schemes in achieving desired levels of sterility when changes are made in product formulas.