Akademik Veri Yönetim Sistemi
Tezin Türü: Yüksek Lisans
Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Gıda Mühendisliği Bölümü, Türkiye
Tezin Onay Tarihi: 2005
Tezin Dili: İngilizce
Öğrenci: Saner Dede
Danışman: HAMİ ALPAS
Özet:The quality and shelf-life of pressure processed (150, 200 and 250 MPa at 25 and 35°C for 5, 10 and 15 minutes) orange, tomato and carrot juices were compared to fresh and thermally pasteurised (60°C for 5, 10 and 15 minutes and 80°C for 1 minute) juices. Treatments were capable of microbial inhibition of juices to non-detectable levels. The change in ascorbic acid content of HHP treated juices was not statistically significant (p>0.05). Both heat treatments at 60 and 80°C, displayed a significant loss and induced a decrease in the free radical scavenging activity but was not affected by HHP treatments. Pressurization at 250 MPa at 35°C for 15 minutes and thermal pasteurization at 80°C for 1 minute and stored at 4 and 25°C for shelf-life analysis. HHP treated juices showed a small loss of antioxidants (below 10%) at both storage temperatures whereas the loss is higher (about 30%) in the heat treated juices through shelf life (30 days). The pressurized juices, stored at 25°C, contained ascorbic acid better than heat treated ones after 30 days. The total color changes were minor (?E=10) for all pressurized juices but for heat pasteurized samples, higher as a result of insufficient antioxidant activity. The pH of juices was not affected by treatment, storage temperature or time. HHP yielded a better product, regarding the studied parameters of the juices compared to the conventional pasteurization. Therefore, HHP treatment (250 MPa, 35°C for 15 minutes) can be recommended for industrial production of fresh fruit and vegetables.