Akademik Veri Yönetim Sistemi
Tezin Türü: Yüksek Lisans
Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Gıda Mühendisliği Bölümü, Türkiye
Tezin Onay Tarihi: 2012
Tezin Dili: İngilizce
Öğrenci: Necmiye Büşra Gültekin
Danışman: HAMİ ALPAS
Özet:The aim of this study was to investigate the effect of high hydrostatic pressure (HHP) treatment (200, 300, 400 MPa; 5⁰C, 15⁰C, 25⁰C; 5 and 10 minutes) on some quality properties of two different squeezing pressure processed pomegranate juices against traditional thermal treatment at 85⁰C/10 min. Among these combinations, for 100 psi squeezed, 400 MPa 15⁰C 5 min and for 150 psi, 400 MPa 5⁰C 10 min were chosen the best. Antioxidant activity, total phenolic content, total monomeric anthocyanin concentration, ascorbic acid content, mannitol content, color values (ΔE) and other routine quality properties as ⁰Brix, pH, titrable acidity besides microbial analyses as total meshopilic areobic bacteria count and total yeast and mould count were investigated. HHP combinations around 400 MPa at 10 min at every temperature were sufficient to decrease the microbial load around 4.0 log cycles for both squeezed juices. All HHP treatments showed no significant decrease at antioxidant activity, total phenolic content and monomeric anthocyanin pigment concentrations while there was a significant decrease (p < 0.05) for thermal treated. Ascorbic acid increased with 5 min HHP treatments but decreased with 10 min. ΔE values were smaller with HHP treatments for all combinations for both squeezed juices. HHP treatments gave lower mannitol content. In shelf life study during 30 days, antioxidant and ascorbic acid levels stayed more stable than control and pasteurized ones. Sensory evaluations, odor and appearance, HHP treatments gave highest results then the others as well as the smallest ΔE values. For all combinations, there was no significant difference for ⁰Brix, pH and titrable acidity values between HHP and thermal treatments.