Table 4 Effect of freezing, thawing methods on pH of blanched sweet potato stems with air containing and vacuum packaging

Freezing method	Thawing method	Package

		Air containing package	Vacuum package

Control		7.30±0.03^ab	7.30±0.03^abc

Conventional freezing -20 C	Room temperature	7.12±0.00^deBx	7.01±0.04^eCy
	Running water	7.16±0.10^cdeBx	7.13±0.01^deBx
	HF1)	7.30±0.08^abAx	7.33±0.03^abcAx
	MW2)	7.28±0.02^abAy	7.10±0.01^deBy

Conventional freezing -40 C	Room temperature	7.13±0.13^deBx	7.18±0.01^cdAx
	Running water	7.14±0.03^deBx	7.32±0.12^abcAx
	HF	7.17±0.09^cdeBy	7.20±0.09^bcdAx
	MW	7.37±0.04^aAx	7.20±0.11^bcdAxy

Immersion freezing -40°C	Room temperature	7.10±0.01^eCx	7.21±0.04^bcdAx
	Running water	7.25±0.18^bcBx	7.33±0.04^abcAx
	HF	7.38±0.04^aAx	7.38±0.12^aAx
	MW	7.22±0.02^bcdBCz	7.35±0.08^abAx

^a-eMeans with different superscripts within the whole column are significantly different (p<0.05).
^A-CMeans with different superscripts within the same freezing method are significantly different (p<0.05).
^x-zMeans with different superscripts within the same thawing method are significantly different (p<0.05).
¹⁾High frequency thawing.
²⁾Microwave thawing.