EFFECT OF BLANCHING PRETREATMENT ON COLOR AND TEXTURE OF APPLE SLICESAT VARIOUS WATER ACTIVITIES

Equilibration of Bed Delicious apple slices to water activities below about 0.6 resulted in increased hardness in blanched, sulfited and unt reated control slices as measured by the force required to shear the s lices. As their water activity was lowered toward 0.29, blanched slice s became about 2.5 times harder than the sulfite or untreated samples. Brown color development in the slices as measured by the C.I.E. value L was maximal at a(w) near 0.7 and less on either side of this water activity. Brown color development over 8 week storage at ERH 53, 65 an d 75% was accompanied by rapid loss of polyphenol oxidase activity and progressive loss of total phenol. Packaging and storage of fruit leat hers and apple slices are discussed in the light of these results.