Investigate the effect of cooking on dietary fiber and moisture content of vegetables. There are 3 periods looked at: raw, short cooked (15-20 min) and long cooked (45-50 min). Vegetables studied were broccoli, carrot, cabbage, and okra. Moisture content increased across all vegetables except broccoli which decreased. Weight loss has previously been attributed to the collapse lignocellulose walls with subsequent extrusions of cellular fluids. Broccoli seemed to have the most variation in dietary fiber during cooking periods due to the formation of indigestible residues during cooking which are isolated together with lignin. The authors suggest that because all NDF values were higher than CF values that CF is not a good indicator of overall fiber present that NDF values should replace the existing CF values found in food tables. NDF = cellulose, hemicellulose and lignin. ADF= cellulose and lignin. Changes between NDF and ADF reflect changes in cellulose alone because hemicellulose and lignin were generally unaffected by cooking. Overall ADF and for the most part CF and cellulose seemed to increase after cooking. Cellulose may increase because it might either have been liberated from the surrounding material or hydrolyzed during cooking process.
My thoughts in relation to our study: How do our NDF and ADF analyses affect the amount of fiber available for analysis? If cellulose can be made more available after heating/ cooking, are we overestimating the amount of fiber available for human consumption?
Broccoli Carrots Cabbage Okra
NDF incr same amt incr only long na incr only long
ADF incr all incr all not disc incr all
Cellulose incr same amt incr only long incr all incr only long
Hemicellulose na na na na
CF incr all incr all incr all incr only long
lignin incr only long na na na
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