No abstract

Diffusion‐extracted (DE) sunflower meal and protein isolate were compared with untreated samples for their nitrogen extractability and moisture adsorption. Nitrogen extractability values of 90% were found at pH 7 or above in the untreated meal, whereas a maximum solubility of only 70% was achieved at pH 9.0 in the DE meal prepared at 60°C. DE meal prepared at 80°C had low solubility over a pH range of 1–11 which indicated substantial denaturation of the sunflower proteins. The untreated isolate showed a sharp minimum solubility point in contrast to the law solubility of the DE isolate over a pH range of 3–7. Moisture adsorption values for the samples held at 5, 20 and 30°C indicated little difference in moisture contents at relative humidities of 11–55%. At higher levels, however, the untreated meal adsorbed more moisture than the DE meal. A reverse trend was noticed for the isolates as the moisture content of the DE isolate was higher than the untreated sample. The rate of moisture uptake by sunflower kernels was slower than that observed with rapeseed or soybean meats and lower total moisture contents were observed after a 4 hr soaking period.

A mathematical model was developed for prediction of temperature fluctuations in warehouse stacks of frozen peas subjected to dithermal storage regimes. The model was tested by comparing its predictions with temperatures measured in frozen peas packed into a slab-shaped container. Satisfactory agreement was found between model and experiment. Other model predictions indicate that large container sizes and rapid fluctuation regimes result in the greatest thermal stability at interior locations in bulk-stored peas. Thermal properties of frozen peas were also determined as part of the experimental verification. The model can be used to evaluate quality changes in frozen products due to d&thermal storage and the energy needed to maintain a certain final quality.