Texture of sauces made from many varieties of apples may be in- 

 fluenced by the amount of vascular tissue in the cortex. However, 

 gross observation of cleared slices led to the conclusion that differences 

 among varieties in this study were not sufficient to explain variations 

 in firmness of cooked tissues on that basis alone. Firmness of apple 

 flesh after cooking may depend also on the amount and kind of cellu- 

 lose, hemicellulose, and pectins originally present, and on the extent of 

 hydrolysis or alteration of these substances during storage and during 

 cooking, with consequent softening and rupture of cell walls and 

 separation of cells. 



The flesh of Delicious apples, most firm in texture of all varieties 

 when cooked, had small cells and thin but intensely stained cell walls, 

 least rupture whether raw or cooked, and least flaky breakdown when 

 cooked. The Rome Beauty variety, next in firmness, also had small 

 cells which when fixed raw were much like those of Delicious apples, 

 but the cell walls were more affected by steaming than were those of 

 the Delicious variety. Golden Delicious, Jonathan, and Stayman 

 apples, which yielded softer or smoother cooked products, had slightly 

 more lightly stained and more fragile cortical cell walls than the other 

 varieties. 



Greater concentration of pectins and hemicelluloses in cell walls of 

 Delicious and Rome Beauty apples is indicated by greater staining ca- 

 pacity. The lower acidity of these varieties may indicate the presence of 

 more cell wall solids in the other varieties (1±2) • The degree of cooking 

 breakdown may be influenced by differences in the water-soluble hemi- 

 celluloses (52) and pectins present. The amount of acid present is also 

 said to influence hydrolysis of non-water-soluble hemicelluloses (37) ; 

 on the other hand, Reeve and Leinback (36) found that high concen- 

 tration of acid did not always mean great softening during cooking. 



Palatability characteristics in relation to chemical 

 constituents of apples 



The palatability characteristics of raw and cooked apples in relation 

 to several chemical constituents are shown in table 22. As might be 

 expected, scores for tartness of raw apples, applesauce, and baked 

 apples showed highly significant correlations with total acidity in 

 apples. Correlation coefficients between natural flavor of raw and 

 cooked apples and total acidity indicated that there was a tendency 

 for raw apples high in acidity to score high in natural flavor, as well 

 as the sauces and baked apples prepared from them. Natural flavor 

 in sauces was influenced more by total acidity of apples than natural 

 flavor in raw or baked apples. The pH of apples was highly correlated 

 with tartness and with natural flavor and sweetness of raw apples, 

 sauces, and baked apples. Natural flavor, sweetness, and tartness in 

 sauces were more highly correlated with pH than were the same 

 palatability factors in raw and baked apples. 



As indicated by a highly significant correlation coefficient of —0.61, 

 baked apples from varieties high in acidity showed a tendency to lose 

 their shape. Trends in scores for flesh texture also indicated that raw 

 apples high in acidity were crisp and not mealy. Consistency of sauce 

 was not significantly correlated with total acidity. 



Apples sweeter than optimum and lacking in natural flavor and 

 tartness contained high percentages of reducing sugar. When these 



72 



