Shelf Life and Moisture Transfer Predictions in a Composite Food Product: Impact of Preservation Techniques

Three techniques to prevent moisture transfer in a multidomain food system constituted by a cookie in contact with a moist filling were investigated: reducing the water activity difference between components, reducing the effective moisture diffusivity of the cereal-based component, and applying an edible moisture barrier at the interface between components. Shelf-life of the food product was extended by 6 days by decreasing the water activity of the moist filling in contact from 0.99 to 0.64 (cookie aw being 0.23, 20°C). Decreasing effective moisture diffusivity from 1.56 to 0.99*10-11 m²/s by the addition of 2.35 g of fat in the formulation of the cookie was limited by technological and organoleptic considerations and allowed an extension of shelf-life of 2 more days. From a technical and nutritional point of view, the application of a sprayed edible barrier at the surface of the cookie was the more effective solution increasing shelf life of almost 8 days for only 1.7 g of fat per cookie.

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Optimization and Prediction of the Drying and Quality of Turnip Slices by Convective-Infrared Dryer under Various Pretreatments by RSM and ANFIS Methods

Foods ◽

10.3390/foods10020284 ◽

2021 ◽

Vol 10 (2) ◽

pp. 284

Author(s):

Ebrahim Taghinezhad ◽

Mohammad Kaveh ◽

Antoni Szumny

Keyword(s):

Energy Efficiency ◽

Color Difference ◽

Moisture Diffusivity ◽

Effective Moisture Diffusivity ◽

Diffusivity Coefficient ◽

Drying Process ◽

Anfis Model ◽

Drying Time ◽

Effective Moisture ◽

Response Variables

Drying can prolong the shelf life of a product by reducing microbial activities while facilitating its transportation and storage by decreasing the product weight and volume. The quality factors of the drying process are among the important issues in the drying of food and agricultural products. In this study, the effects of several independent variables such as the temperature of the drying air (50, 60, and 70 °C) and the thickness of the samples (2, 4, and 6 mm) were studied on the response variables including the quality indices (color difference and shrinkage) and drying factors (drying time, effective moisture diffusivity coefficient, specific energy consumption (SEC), energy efficiency and dryer efficiency) of the turnip slices dried by a hybrid convective-infrared (HCIR) dryer. Before drying, the samples were treated by three pretreatments: microwave (360 W for 2.5 min), ultrasonic (at 30 °C for 10 min) and blanching (at 90 °C for 2 min). The statistical analyses of the data and optimization of the drying process were achieved by the response surface method (RSM) and the response variables were predicted by the adaptive neuro-fuzzy inference system (ANFIS) model. The results indicated that an increase in the dryer temperature and a decline in the thickness of the sample can enhance the evaporation rate of the samples which will decrease the drying time (40–20 min), SEC (from 168.98 to 21.57 MJ/kg), color difference (from 50.59 to 15.38) and shrinkage (from 67.84% to 24.28%) while increasing the effective moisture diffusivity coefficient (from 1.007 × 10−9 to 8.11 × 10−9 m2/s), energy efficiency (from 0.89% to 15.23%) and dryer efficiency (from 2.11% to 21.2%). Compared to ultrasonic and blanching, microwave pretreatment increased the energy and drying efficiency; while the variations in the color and shrinkage were the lowest in the ultrasonic pretreatment. The optimal condition involved the temperature of 70 °C and sample thickness of 2 mm with the desirability above 0.89. The ANFIS model also managed to predict the response variables with R2 > 0.96.

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