Study on the splitting by hot-air drying of Camellia oleifera fruit

In order to explore the feasibility of hot air splitting of Camellia oleifera fruit, the effect of hot air temperature on peel splitting, the moisture state and moisture migration in peel, the peel microstructure and the seed color were studied. The results showed that higher hot air temperature could accelerate the splitting rate, the optimum temperature for splitting C. oleifera fruit was 90–110 °C considering the seed quality. Page model was the most suitable for describing the drying kinetic characteristics of C. oleifera fruit. Nuclear magnetic resonance (NMR) revealed the changing of the dehydration rate, the migration rate of bound water, immobilized water and free water in peel during hot air drying. The expansion of micro-channels in peel was conducive to moisture migration in the early splitting stage, but microstructure damaged in the late splitting stage accompanied by loose disorder of micro pores, serious shrinkage and deformation of peel.

The influence of continuous and periodic microwave drying on rosemary: drying and temperature kinetics

Continuous microwave is a heavily studied drying method known for its effectiveness and efficiency, however, it leads to overheating in most cases. The primary objective of the present research is conducting and evaluating a comparative study of continuous and periodic microwave drying on rosemary for various power levels (6, 9 and 12 W/g) and different pulse ratios to overcome the overheating challenge. The evaluation and assessment were based on drying and temperature kinetics. Drying kinetic study revealed that periodic and continuous microwave drying at 12 W/g had the least drying duration of 12.5 and 11 mins, respectively. Likewise, both processes had the highest drying rates of 0.364 and 0.461 kg H2O/ kg dry basis min. The temperature kinetic study showed that the periodic microwave drying (71.4°C) resulted in a lower maximum sample temperature than continuous microwave drying (79.2°C). The periodic microwave drying with higher pulse ratios had a more even heating throughout the drying process than lower pulse ratios. Thereby, periodic microwave drying at 12 W/g and the highest pulse ratio was deemed to be the most suitable drying process for rosemary. The four thin layer models, namely Page, Modified Page, Midilli & Kucuk and Modified Midilli & others, were the most suitable to describe the drying kinetics of rosemary.

MODELING OPEN AIR AND SHADE DRYING OF CORYMBIA CITRIODORA LEAVES FOR THE ESSENTIAL OIL PRODUCTION

In the literature, the drying mechanism were generally analyzed in terms of effective diffusivity through the pseudo first order diffusion model. This process was revisited through the modified Peleg model, assuming the drying as a moisture desorption versus drying time. The leaves of Corymbia citriodora acclimatized in the Congo Brazzaville “Plateau des Cataractes” were dried in open air and under shade thanks to a domestic scale of essential oil production. One obtains following model parameters: kinetic constant k1: 0.8555 - 2.1355 d.(g/g)-1, extraction capacity constant K2: 1.5255 - 1.8733 (g/g)-1; end equilibrium moisture X∞ = 0.53 - 0.66 g/g. and first order drying kinetic constant k = K2/k1: 1.71 - 1.78 d-1. Pseudo first order diffusion model fits experimental data with k = 0.368 - 0.587 d-1 and t1/2 = 1,18 - 1,88 d.. These results needed for the optimization of proccess and sizing equipments came from a fast graphic data processing, with low computer inputs.

EFFECT OF DRYING CONDITION ON DRYING RATE AND PHYSICOCHEMICAL OF MORINGA OLEIFERA LEAVES MILK POWDER

People with animal protein allergies are not allowed to consume cow’s milk. Moringa oleifera are rich in a number of nutrients such as protein, vitamins, calcium, iron, and micronutrients, and can be an alternative to substitute cow’s milk. This study aimed to evaluate the influence of drying air temperature and air velocity on drying rate, drying kinetic and the physicochemical properties of moringa milk powder. The drying process was conducted using a tray dryer with a foam mate drying method. Moringa leaves and sesame seeds were crushed for 10 minutes using a blender. The mixture was filtered by filter paper and then mixed with dextrin and eggwhite as foaming agents of 20% and 15% weight, respectively. A baking sheet containing Moringa paste with a thickness of 5 mm was inserted into the tray dryer. The hot air at velocity variations of 0.2 m/s and 0.3 m/s, and temperature variations of 90°C, 110°C, and 130°C were applied to dry moringa paste. Lewi’s model was used to determine the drying kinetic of moringa oleifera milk powder. The optimum drying process occurred at the temperature of 130°C and the air velocity of 0.2 m/s with a critical time (tc) 20 minutes, the critical water content of the sample (Xc) 2.304 kg H2O/kg-dry-solids, a constant drying rate (Rc) 0.365 kg H2O/minute.cm2, and drying kinetic constant (k) 0.0335 min-1. This study succeeded in producing powdered milk with the highest fat content of 14% while the protein content of 19.2%.

Sustainable Development of Apple Snack Formulated with Blueberry Juice and Trehalose

Novel products that carry concrete and relevant health benefits, with texture and flavor not substantially different from already available products, are generally well accepted by consumers. Vacuum impregnation is a non-thermal technology that allows the enrichment of fruit with different ingredients in solution. The characteristic of the resulting product is a combination of both the solid matrix and the impregnation solution. This work aimed at: (i) evaluating the effect of trehalose on anthocyanin retention after drying of apple snacks vacuum impregnated with blueberry juice; (ii) modelling the air-drying kinetic, proposing an image analysis approach to monitor the drying process. Four mathematical models successfully fitted the drying experimental data, obtainingequations that could be used in the implementation of this process at industrial scale. The drying kinetics of samples impregnated with blueberry juice and trehalose were faster when compared to the control sample. Samples impregnated with blueberry juice and 100 g/kg of trehalose retained nearly four times more anthocyanin after drying when compared to the control.