Rice is typically stored in the form of whole kernel (rough rice with husk) to minimize quality changes, although storage of milled rice is more convenient and economically feasible. Expenses associated with low temperature storage of rough rice have prompted the need for alternative processing and storage methods, especially in developing countries. Thus, the effects of temperature (30-60 °C) on quality characteristics of milled Catahoula rice during 31 d of storage were investigated. Additionally, the physicochemical properties and cooking quality of rice milled at different intensities (light, medium, and heavy milling) were analyzed. Storage temperature and milling intensity were found to affect the quality of stored and cooked rice, respectively. Higher levels of rice milling intensity correlated with greater water absorption, easier compression, and faster gelatinization of the cooked kernels. During the storage time, protein contents were consistent, while lipid contents slightly decreased. The milled rice experienced an increase in lightness and decrease in moisture content with increasing storage temperatures. This study revealed that by adjusting rice milling parameters and storage temperature the quality of Catahoula rice can be controlled.
The effect of a combined osmo‐dehydro‐cryogenic‐freezing process on quality characteristics of fruits and vegetables was evaluated. Cut‐tomato‐pieces were used as a model vegetable to evaluate the process. Tomatoes had 15.74% water loss and 0.22% solids gain after 24 h of osmotic dehydration in a 55% (w/w) maltodextrin solution at 35C, and increased redness was observed in osmotically dehydrated samples with lycopene content of 1244.78 µg/g of dry mass. Under liquid nitrogen cryogenic freezing at −40C osmotic pretreated tomato samples had shorter freezing time (3.13 min) and higher freezing rate (16.53C/min) than untreated samples (4.48 min and 11.58C/min, respectively). Pretreated‐thawed tomato samples had less drip loss, higher retention of color and lycopene than untreated samples after thawing. Pretreated‐thawed tomato samples had less cell collapse than untreated‐thawed samples. This study demonstrated that osmotic pretreatment could improve color, reduce nutritional quality loss, and texture degradation of tomatoes during cryogenic freezing.
Practical Applications
A pre‐freezing process such as osmotic dehydration may help to reduce quality loss of fruits and vegetables during cryogenic freezing as a result of removing part of the water. In this study, a combined osmo‐dehydro‐cryogenic‐freezing was developed for minimizing quality changes of fruits and vegetables during freezing. Cut‐tomato‐pieces were used as a model fruit to evaluate the process. Quality characterization was carried out by evaluating the lycopene content, color and cell structures of osmotically dehydrated frozen samples. We found that the combined osmotic dehydration and cryogenic freezing reduced the quality loss of tomato samples when compared to the same freezing process without any pretreatment. This combined process of osmotic dehydration and cryogenic freezing can be applied to produce high quality commercially frozen fruits and vegetables.
This study evaluated the effect of bambara groundnut supplementation on the physicochemical properties of local rice flour and baked crackers. Bulk and true density, porosity, water absorption index, oil absorption capacity, pasting properties by RVA, morphological appearance by SEM, color by calorimetry, and textural properties by TA.XT2 analysis of wheat and two formulations of rice-legume flours and crackers were studied. Moisture (10.94%) and carbohydrate (77.42%) levels were significantly greater in wheat flour than the rice-legume flours, while the reverse was true for fat and ash. Also rice-legume flours had significantly greater water and oil absorption capacity and lower water solubility compared to wheat flour. Compared to wheat crackers, rice-legume crackers had greater fat and ash, 20.51 and 3.57%, respectively, while moisture was significantly lower in the rice-legume crackers by 41 to 58%. Rice legume crackers were significantly harder and had significantly increased spread ratio. The results obtained from the development of locally grown rice and underutilized legume bambara groundnut showed great promise in physicochemical and functional properties and may be a good replacement for wheat flour to serve as a gluten-free product.
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