Effects of cryoprotectant mixtures on physical properties of frozen and thawed puréed cooked potatoes: some introductory studies


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Freezing and thawing of cooked vegetables can have deleterious effects on the organoleptic and physical properties. In this study, the ability of mixtures of certain cryoprotectants to ameliorate these effects in cooked, frozen-then-thawed mashed potatoes was studied. Ingredients selected were hydrocolloids (xanthan, guar, carrageenan and pectin) and dairy proteins (sodium caseinate and whey protein concentrate). Ingredients were incorporated as mixtures of: (1) guar, pectin and whey protein concentrate; and (2) xanthan, carrageenan and sodium caseinate. Experimental design techniques were used to design the experiments and evaluate the results. Both ingredient mixtures significantly reduced maximum resistance to penetration and centrifugal drip loss. No practically significant effect of either treatment on purée colour was detected. Partial least squares regression models of changes in resistance to penetration with ingredient concentration produced goodness of fit (R2) and goodness of prediction (Q2) indices of 0.84 and 0.59 (mixture 1) and 0.76 and 0.51 (mixture 2), respectively. For drip loss, the corresponding values were 0.77 and 0.34 (mixture 1) and 0.77 and 0.44 (mixture 2), respectively. This approach may have potential for designing cooked potato purées with specified resistance to shear and drip loss values.