Solute conditions inside cooked bean pods were adjusted by soaking the pods in different solutions. Interactions of Ca" and Na' showed increasing firmness as Ca" concentration was raised and decreasing firmness as Na+ was raised. Chelating agents removed Ca" and decreased firmness. Higher p H gave lower firmness except in the presence of excess Ca". Ihe presence of Na' decreased the effect of pH on firmness. Urea decreased firmness when pods had been previously treated with a chelator. l h e effects of treatments on firmness were related to the behavior of pectin solutions and gels.

The effects of salts and pH on softening during cooking were tested by modifying solutions in which pods were heated. Ca displaccmcnt was minimized by soaking heated pods in 0.2M CaCI, before measuring firmness. Softening was increased independently by the prcsence of salts and when pH was raised from 5.2 to 6.2. Cations decreased firmness in the order Li > Na = K > NH4 and Ca > Mg. Anions decreased the firmness in the order SO1 > acetate > Cl > Nos. Firmness differences persisted at long heating times. The results support the hypothesis that pectin p-elimination was the principal softening reaction.

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