DEVELOPMENT OF FROZEN-FRIED YAM SLICES: OPTIMIZATION OF THE PROCESSING CONDITIONS

The research performed on yam processing mainly concerns the production of crisps and flour. However, its transformation into deep-frozen French fries does not necessitate any other equipment than those used for potatoes. The industrial process of production of frozen French fries traditionally includes a pre-frying step. These steps contribute to the development of color and crispness, and the oil partially absorbed inhibits dehydration during the freezing step. The aim of this study was to optimize frying conditions of deep-frozen fried yam (Dioscorea cayenensis var Kponan) slices. The effect of pre-frying time and temperature, final frying time and temperature on the oil uptake, texture, dry matter and colour of the fried yam slices has been studied. Frying conditions optimized with Box-Behnken experimental design were short pre-frying and frying conditions at high temperature characterized by pre-frying temperature at 157-170°C during 5-9s and frying temperature at 181-188°C for 2min 15s-2min 30s; or long pre-frying and frying conditions at low temperature characterized by pre-frying temperature at 150-158°C during 10-15s and frying temperature 170-177°C for 3-3min 15s. An adiabatic system was also developed by means of an insulator in which the core temperature of fried yam slices can be maintained constant at about 55°C after 15min of cooling, facilitating texture measurements at constant temperature. The present results may help in choosing the yam slices frying condition to be applied in order to achieve the desirable fried yam slices quality, required for protection against certain diseases like obesity. These models may also provide guidance as to how to control these quality parameters by altering four key environmental factors, pre-frying temperature and time and, final frying temperature and time. This process can also be commercialized and does not necessitate any other cost for equipment than those used for potatoes French fries and might be an interesting way of added value processing for this highly perishable yam tuber

Effect of glycerol, peanut oil and soybean lecithin contents on the properties of biodegradable film of improved cassava starches from Côte d’Ivoire

— Edible films have been successfully used in the food packaging industry for several decades. Today natural polysaccharides, including cassava starch,are increasingly being used in the production of such biodegradable edible films and food packaging. In Côte d'Ivoire, there are improved cassava varieties whose starches have not yet been tested in the production of biodegradable films. In thisstudy, the optical and mechanical properties and the water solubility of starch-based composite films of four improved cassava varieties withadded glycerol, peanut oil and soy lecithin were determined. Starchwas obtained by cold water extraction from native cassava from the varieties Bocou 1, Bocou 2, Yavo and TMS. Films preparation was made bycasting methodwithcassava, glycerol (25-30 %), peanutoil (5-10 %) and soybean lecithin (0-5 %). Increasing the glycerol content, increased L*color valueand elongationat break and decreased a*, b*, colourdifference (ΔE*ab) and tensilestrength of the composite films. Also, increasing the oil content from 5 to 10%, increased the opacity, b*, ΔE*ab, water solubility, elongationat break but decreased L*, a* and tensilestrength. Similarly, increasing the soy lecithin content from 0 to 5%, increased the opacity, L*, b* and ΔE*ab, but decreased a*, of the starch-based composite films. The results suggest an ideal formulation of 4% starch/25% glycerol/5% oil/5% soy lecithinfor a film with optimum mechanical properties with low solubility

Effect of Edible Coating based on improved Cassava Starch on Post-Harvest quality of fresh Tomatoes (solanum lycopersicum l.)

peer reviewedComposite coatings based on improved cassava starch have the capacity to preserve the quality and extend the shelf life of fresh tomatoes. Two new edible composites coatings C1 (4% starch/25% glycerol/5% oil/5% soybean lecithin) and C2 (4% cassava starch/microcrystalline cellulose 30%/25% glycerol/5% oil/5% lecithin) were compared with the commercially available SemperfreshTM coating and no coating. Different coatings/no coating were applied to fresh tomatoes that were subsequently stored at 20 ± 2°C and 70 ± 2% relative humidity for 4 weeks. Tomatoes coated with the composite coatings C1 and C2 based on improved cassava starch showed a significant (P < 0.05) delay in changes of firmness, weight, titratable acidity, pH, total soluble solids, sugar/acidity ratio and colour development compared with both SemperfreshTM and uncoated control fruit. The results demonstrated that our assessed combination of improved cassava variety starch vegetable oil, glycerol, soy lecithin and cellulose and derivates can be used as edible coating to increase the shelf life of tomatoes stored at 20 ± 2°C up to four weeks