AN IMPROVED DIFFERENTIAL SCANNING CALORIMETRY STUDY FOR THERMAL PROPERTIES OF PEKMEZ SAMPLES ADULTERATED WITH SUGAR SYRUP

Öz

This research was carried out to determine the pH, titratable acidity, ash, specific gravity, color (L*, a*, b*), water activity, electrical conductivity, glass transition temperature (Tg) and melting characteristics of grape and mulberry pekmez samples adulterated with different levels (10%, 30%, 50%) of high fructose corn syrup (HFCS). Ash, titratable acidity and electrical conductivity values have decreased significantly (P<0.05) with the level of adulteration and determined that these properties can be used as a criterion in the determination of adulteration. Two glass transition temperatures occurring between -25.64℃ to -32.58℃ (Tg1) and 23.29℃ to 31.22℃ (Tg2) were detected in all pekmez samples. The single glass transition temperature was determined in the pekmez samples diluted with water, and both the glass transition temperatures and the onset, peak, end temperatures and enthalpy values of the melting peaks increased significantly with the increase in the amount of adulteration (P<0.05).

Anahtar Kelimeler

• Pekmez
• differential scanning calorimetry
• glass transition temperature
• adulteration
• sugar syrup

ŞEKER ŞURUBUYLA TAĞŞİŞ EDİLEN PEKMEZ ÖRNEKLERİNİN TERMAL ÖZELLİKLERİ İÇİN GELİŞTİRİLMİŞ BİR DIFFERENTIAL SCANNING CALORIMETRY ÇALIŞMA

Öz

Bu araştırma, farklı seviyelerde (%10, %30, %50) yüksek fruktozlu mısır şurubu (HFCS) ile tağşiş edilmiş üzüm ve dut pekmezlerinin pH, titre edilebilir asitlik, kül, özgül ağırlık, renk (L*, a*, b*), su aktivitesi, elektriksel iletkenlik, camsı değişim sıcaklığı (Tg) ve erime özelliklerinin belirlenmesi amacıyla yürütülmüştür. Tağşiş seviyesi arttıkça kül, titre edilebilir asitlik ve elektriksel iletkenlik değerlerinin önemli derecede (P<0.05) azaldığı ve bu özelliklerin tağşişin belirlenmesinde kriter olarak kullanılabileceği belirlenmiştir. Pekmez örneklerinin tamamında -25.64°C ile -32,58°C (Tg1) ve 23.29°C ile 31.22°C (Tg2) arasında oluşan iki camsı geçiş sıcaklığı tespit edilmiştir. Su ile seyreltilen pekmez örneklerinde tek camsı geçiş sıcaklığı belirlenmiş olup, tağşiş miktarının artmasıyla hem camsı değişim sıcaklıkları hem de erime piklerinin başlangıç, pik, bitiş sıcaklıkları ve entalpi değerleri önemli derecede artış göstermiştir (P<0.05).

Anahtar Kelimeler

• Pekmez
• differential scanning calorimetry
• camsı değişim sıcaklığı
• tağşiş
• şeker şurubu

Kaynakça

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