Nonenzymic browning reactions in boiled grape juice and its models during storage

Effects of prolonged heating on antioxidant activity and colour of honey

“…This indicates that increase in treatment temperature favoured both antioxidant activity and BPF. The calculated activation energy using Arrhenius equation for BPF was 122 kJ/mol at 50-70 C. This value was lower than the value of 132 kJ/mol given for boiled grape juice (Bozkurt et al, 1999) and higher than 77.1 kJ/mol for apple puree , indicating that browning reaction in honey is more temperature sensitive compared to boiled grape juice but less sensitive to temperature increase than apple puree. The difference in browning rate of honey could be explained by differences in its amino acid and reducing sugar contents compared to both boiled grape juice and apple puree.…”

“…Zero-order ki-netic model described adequately BPF at all tempera-tures, which is in agreement with previous studies. Zero-or first-order kinetic models have been used to evaluate the appearance of non-enzymatic browning (Bozkurt, Gö ǧ ü s, & Eren, 1999;Carabasa-Giribet & Ibarz-Ribas, 2000;Davies, Wedzicha, & Gillard, 1997;Garza, Ibarz, & Giner, 1999;Kwok, MacDougall, & Niranjan, 1999;Maskan, Kaya, & Maskan, 2002;Toribio & Lozano, 1984). First-and secondorder models also tested but they gave lower correlation coefficients.…”

Application of fuzzy expert system approach on prediction of some quality characteristics of grape juice concentrate (Pekmez) after different heat treatments

“…Mulberry, apricot, carob and persimmon are the common fruits used for pekmez production. Pekmez contains high amounts of sugar, minerals and organic acid and is very important in human nutrition (Bozkurt et al 1999;Yoğurtçu and Kamışlı 2006).…”

“…Non-enzymatic browning reactions during processing and storage are the well known problem in pekmez production. Maillard reactions result in undesirable colour, odour and flavour changes and are followed by the formation of intermediates such as 5-hydroxymethyl furfural (HMF), particularly under acidic conditions and finally brown pigment formation (Bozkurt et al 1999).…”

“…In fresh foods, the HMF level is close to zero. HMF is also considered as one of the indicators of quality parameters of pekmez (Bozkurt et al 1999). Zadeh (1965) first reported on a novel way of characterizing nonprobabilistic uncertainties, which he called "fuzzy sets".…”