They found that in the raw state, the firmness was found to decrease in the following order: cauliflower, beans, potatoes, peas and corn. All of the vegetables were firmest at pH 4 in the cooked state. In general, the vegetables were softest at pH 10; at pH 2, the firmness was only surpassed by the results of pH 4. These results agree favorably with those of Doesburg [34] who showed that plant tissues possess maximum firmness at pH 4.0–4.5. He observed decreased firmness at pH values both higher and lower than pH 4. Beans and cauliflower showed the most dramatic changes due to cooking media. They exhibited significant linear effects since their firmness decreased as pH increased. In general, the most cooking solution fiber was extracted at pH 10, the lowest amount at pH 4. Those vegetables which showed the largest changes in shear values upon cooking also showed the greatest amount of material extracted into the cooking media. Cauliflower and peas showed the most material extracted into the cooking media, followed by beans, potatoes and corn. Pectin is usually thought to be stable in acid and unstable in alkali [68]. Corn and potatoes displayed no significant changes in water-insoluble hemicellulose from pH 2 to pH 10. Van Soest and Robertson [152] and Heller et al. [59] found that most plant tissues show increased soluble hemicellulose at both high- and low-pH values; at neutral pH, hemicellulose is the least soluble. The data showed no significant changes in cellulose with cooking which correlated with the strongly acidic conditions needed to degrade cellulose.