Giuseppina Adiletta

Mathematical Model with Shrinkage of an Eggplant Drying Process

In this paper, the effect of a pretreatment on an eggplant drying process is investigated by using a suitable developed mathematical model with shrinkage. The objective is to assess the role of volume variation due to changes in pore structures in the dehydration processes. Parameters assessing eggplant quality are also taken into account and collected both with and without pretreatment. The built model is used to analyze evolutions of dehydration processes carried out at two temperatures to provide evidences of the advantages of using pretreatment to assure high quality of end products.

Effect of Abrasive Pretreatment on Hot Dried Goji Berry

Goji (Lycium barbarum L.) is a Solanaceous deciduous shrub that grows in China, Tibet and other parts of Asia. Nowadays, goji berries are known as being very rich in nutrients with high antioxidant capacity, fact for which they were included in the novel category of “superfruits”. Goji berries contain high amounts of antioxidants, carotenoids, vitamin A and zeaxanthin. Most of goji berries produced are dried because they are very delicate fruits. Drying process improves fruit stability, since it decreases considerably the water activity of the food, reduces microbiological and enzymatic activity and minimizes physical and chemical reactions during storage. However, drying of goji berries can be difficult due to the wax layer surrounding the fruit and the health properties may be reduced by long exposure to high temperatures.In this study, a physical wax abrasive pretreatment was used to carefully remove the wax layer and reduce drying time. The abrasion of the goji peel was carried out in a motorized drum lined inside with sandpaper. The rotating time was optimized to reduce the damage to the fruits. The drying characteristics of pretreated and untreated fruits were studied using a convective oven at 60 °C and air velocity of 2.1 m/s.The drying kinetics and fruit quality parameters such as colour, sugars and antioxidant activity were evaluated before and after drying. The results showed that the dried fruit were obtained in less time when they were pretreated (from 21 h for untreated samples to 15 h for pretreated samples), preserving better the colour, increasing the antioxidant activity and maintaining the same sugar content with respect to the untreated case.

Characterization of pears during drying by conventional technique and portable non invasive NMR

Characterization of Pears During Drying by Conventional Technique and Portable non Invasive NMR Giuseppina Adiletta, Paola Russo, Noemi Proietti, Donatella Capitani, Luisa Mannina, Alessio Crescitelli , Marisa Di Matteo Dipartimento di Ingegneria Industriale, Università di Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano (SA), Italy Dipartimento di Ingegneria Chimica Materiali Ambiente, Sapienza Università di Roma, Via Eudossiana 18, 00184, Roma, Italy Laboratorio di Risonanza Magnetica “Annalaura Segre”, Istituto di Metodologie Chimiche, Area della Ricerca di Roma 1, CNR,via Salaria Km 29,300 00015 Monterotondo (Rm) Italy Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, Piazzale Aldo Moro 5, Italy IMM-CNR Via Pietro Castellino 111,80131 Napoli, Italy paola.russo@uniroma1.it

Experimental analysis and mathematical modelling of the effect of starch gelatinization on chestnuts rehydration

The paper presents an experimental and modeling study of the rehydration process of air-dried chestnuts. Sorption curves are obtained for chestnuts dried at 40, 60, and 80 C immersed in water at 90 C and differential scanning calorimetry (DSC) measurements are performed to characterize the evolution of the starch gelatinization process on the transport of water during rehydration. In this way, stages of the rehydration process governed by different physical mechanisms are identified. A large growth in the absorption rate is observed at intermediate times due starch gelatinization while slow absorption is found at large times due to the swelling of the sample. A mathematical model is therefore presented enabling to describe the effect of diffusion, swelling and starch gelatinization. Parametric estimation of the model parameters is performed by nonlinear regression techniques providing indications on how to select processing conditions so as to achieve desired characteristics of the final product..