Heat and Mass Transfer Modeling to Predict Temperature Distribution during Potato Frying after Pre-Treatment with Pulsed Electric Field

Based on unsteady state heat conduction, a mathematical model has been developed to describe the simultaneous heat and moisture transfer during potato frying. For the first time, the equation was solved using both enthalpy and Variable Space Network (VSN) methods, based on a moving interface defined by the boiling temperature of water in a potato disc during frying. Two separate regions of the potato disc namely fried (crust) and unfried (core), were considered as heat transfer domains. A variable boiling temperature of the water in potato discs was required as an input parameter for the model as the water is evaporated during frying, resulting in an increase in the soluble solid concentration of the potato sample. Pulsed electric field (PEF) pretreatment prior to frying had no significant effect on the measured moisture content, thermal conductivity or frying time compared to potatoes that did not receive a PEF pretreatment. However, a PEF pretreatment at 1.1 kV/cm and 56 kJ/kg reduced the temperature variation in the experimentally measured potato center by up to 30%. The proposed heat and moisture transfer model based on unsteady state heat conduction successfully predicted the experimental measurements, especially when the equation was solved using the enthalpy method.

Antitumor and cytotoxic effect of different partitionates of methanol extract of Trema orientalis : A preliminary in-vitro study

Herbal drugs are widely used in the primary health care system now-a-days and the use is increasing day by day. Thus extensive research to confirm the bioactivity of plant extract is very essential. The aim of this research was to determine the antitumor and cytotoxic actions of solvent-solvent partitioned fraction (n-hexane, ethyl acetate and hydro-methanol) of the methanol extract of root of Tremaorientalis. The antitumor activity of different fractions of plant extract was evaluated by potatodisc bioassay method where Agrobacterium tumefaciens was used to induce tumor on potato disc. On the other hand, the cytotoxic effect was determined by brine shrimp lethality bioassay technique. The ethyl acetate fraction of the plant extract showed 35.51% and 62.89% inhibition of tumor formation in potato disc bioassay method at 50 µg/disc and 100 µg/disc respectively. The hydro-methanol extract showed 37.51% inhibition of tumor formation at 100 µg/disc while at 50 µg/disc no significant inhibition was observed. In contrast, n-hexane fraction did not show any antitumor activity. In cytotoxic study by brine shrimp lethality bioassay, the lethal concentration-50 (LC50) value of the n-hexane, ethyl acetate and hydro-methanol fraction was 1377.03 µg/ml, 11.67 µg/ml and 48.62 µg/ml respectively. Ethyl acetate and hydro-methanol fractions of the solvent-solvent partitioned methanol extract of T. orientalis showed high antitumor and cytotoxic effect. These fractions are highly promising for further exploration to identify the bioactive compounds.