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• Examination of physical properties of final product and drying properties of combined (convective pre-drying and freeze finish-drying) dehydration method

  5-12

  Tamás Antal

  Views:

  181

  In this study, the effects of freeze drying (FD), hot-air drying (HAD) and combined drying (HAD-FD) on drying characteristics, energy uptake, texture, rehydration and color of carrot were investigated. Results showed that HAD-FD significantly improved the drying time compared with FD under the same operating conditions, and the HAD-FD can reduce the total cost of dehydration. The drying kinetics was described by the Henderson-Pabis and the third degree polynomial models in the case of HAD, FD and HAD-FD. The HAD carrot samples were exhibited shrinkage, case hardening, poor rehydration and brown surface. The FD carrot cubes appeared porous structure, excellent rehydration, soft texture and loose color. The HAD-FD samples were superior to HAD products and was nearer in quality to FD products with respect to appearance, rehydration and surface resistance (texture). Finally, it is concluded that HAD-FD is effective in improving the FD drying rate. However, the combined drying has a small-scale adverse effect on product quality.

• Microbial assessment of potential functional dairy products with added dried herbs

  59-63

  Kármen Anita Kiss

  Viktória Kapcsándi

  Rebeka Ligeti

  Erika Hanczné Lakatos

  Views:

  137

  The market of dairy products is a dynamically developing sector of the food industry. Potential, functional dairy products, made by adding herbs or spices, will have antimicrobial and antioxidant effect due to the active biochemical agents of the plant additives. Furthermore, these active components will widen the storage life of food products and enhance their organoleptic properties too. We worked out a technology for creating fresh cheeses using a gentle pasteurizing method by treating the mixture of raw milk and 1.5% fat contained in commercial milk. As herb additives, we used citronella (Melissa officinalis), and peppermint (Mentha x piperita) harvested by us and dried them via Tyndall-method in convective dryer on 40 °C for 5.5 hours per day. The drying period took three days. We bought dried citronella and mint from the supermarket, which were dried by ionizing radiation, to compare the microbiological pollution with the herbs dried by us.

  The main target of this research was to create a microbiologically stable, potential functional dairy product. However, because of the bad quality of the raw milk and the gentle heat treatment we used for sterilizing bulk milk, or else, cheeses were not safe for human consumption. As a consequence, we need further studies to modify our technology and get a microbiologically stable product.