Üzümden "üzüm özü" adında yeni bir ürün eldesi üzerine bir araştırma | A research on obtai̇ni̇ng a new product called ''üzüm özü'' from grape

In this study, two different grape varieties being the Cardinal (red) and the Italian (white) were used. After the grapes minched were divided in two groups; the first one was seedless and skinless and the second one was having skin and seed, then they were processed as wet-milled age. The resulting milled grape paste was concentrated until reaching to 78% brix in seedless üzüm özü and 44% brix in üzüm özü with seed at 65, 75, 85 and 100 °C. After then pH value, TA (Titration Acidity) (%), TDM (Total Dry Matter), Ash (%), Brix (%), TPM (Total Phenolic Matter), IC50, HMF, rutin, quercetin, catechin, epicatechin and gallic acid content and color values of the initial product and the üzüm özü concentrated at four different temperatures (vacuum) were measured. Lastly, amount of HMF and phenolic compounds were determined by HPLC.In this study, the pH value in the production of üzüm özü compared to the initial pH value decreased, on the contrary the TA% values increased were determined. While pH value was determined between 3.51-4.05, titration acidity was determined between 1.047-1.532. In üzüm özü with seed total dry matter content was found between 44.70-45.22% in spite of the fact that in seedless üzüm özü total dry matter was found between 79.80-80.18%. Brix value was determined 78.20-78.58 in seedless üzüm özü while in üzüm özü with seed brix value was determined 43.58-44.09. Ash content was found between 1.956-2.358%.In this study, total phenolic content was importantly decreased during production of üzüm özü. It was found that all grape extracts the maximum reduction occured at 100 ºC. Total fenolic content was determined between 7204 -20126 mg/kg DM. IC50 value was found between 38.36-94.18 μg/ml.During process, occuring of HMF was significantly increased. The highest amounts of HMF were found in üzüm özü which product at 100 ºC. The highest amount of HMF was found in white seedless üzüm özü which product at 100 ºC while the lowest amount of HMF was found in red üzüm özü with seed which product at 65 ºC.During production of üzüm özü L* values were significantly decreased. However in a* and b* value were no found specific increase or decrease. L* value was determined to range from 21.95 to 40.54.In this study, during production of üzüm özü, when process temperature increased the amount of phenolic compounds analyzing decreased was determined. Rutin amount 0.25-73.48 mg/kg DM, quercetin amount 0.34-87.28 mg/kg DM, catechin amount 0-197.6 mg/kg DM, epicatechin amount 0-24.5 mg/kg DM, gallic acid amount 0-185.8 mg/kg DM were determined.