71 CURVE FITTING PARAMETERS OF COLOR VARIABLES OF PISTACHIO NUT CREAM DURING STORAGE PERIOD Abstract Pistachio nut cream was produced by using pistachio nut, powdered sugar, defatted milk powder, margarine, lecithin and vanilla. Spreadable pistachio nut creams were stored at 4 and 20 °C up to 240 days. Curve fittings of color variables (L, a, b) and moisture content (%), 2-tiobarbutric acid, browning indices, total chlorophyll, chlorophyll a and b values of spreadable pistachio nut cream were investigated during the storage period. Different mathematical expressions investigated for the curve fittings as exponential, logarithmic, rational, polynomial, Peleg, Weibull, Gaussian, power, Fourier and sin functions. Exponential and cubic polynomial equations gave the best fitting results due to the high regression coefficient (r 2 ), and lower RMSE (%) and SSE (%) values. Keywords: Pistachio nut cream, color variables, curve fittings, exponential and polynomial equations ANTEPFISTIĞI KREMASININ RENK DEĞİŞKENLERİNİN DEPOLAMA ESNASINDAKİ EĞRİ UYDURMA PARAMETRELERİ Özet Antepf›st›¤› kremas›, pudra flekeri, ya¤s›z süt tozu, margarin, lesitin ve antepf›st›¤› kullan›larak üretilmifltir. Sürülebilir antepf›st›¤› kremas›, 4 ve 20 °C'de 240 gün süreyle muhafaza edilmifltir. L, a, b renk de¤iflkenleri ve nem miktar› (%), 2.tiobarbütrik asid, esmerleflme indisi, toplam klorofil, klorofil a ve b de¤erleri aras›ndaki matematiksel iliflkilerin belirlenmesine çal›fl›lm›flt›r. Matematiksel iliflkilerin araflt›r›lmas›nda eksponensiyal, logaritmik, oransal, polinom, Peleg, Weibull, Gauss, üslü model, Fourier ve sinüs eflitlikleri kullan›lm›flt›r. Eksponensiyal ve polinom eflitliklerinin yüksek regresyon sabiti (r 2 ), düflük RMSE (%) ve SSE (%) de¤erlerine göre en uygun eflitlikler oldu¤u belirlenmifltir. Anahtar Kelimeler: Antepf›st›¤› kremas›, renk de¤iflkenleri, e¤ri uydurma, eksponensiyal ve polinom eflitlikleri Ö. Faruk Gamlı 1 *, İbrahim Hayoğlu 2 1 Korkut Ata University, Vocational High School, Bahçe - Osmaniye, Turkey 2 Harran University, Agricultural Engineering, Food Engineering Department, fianl›urfa - Turkey Received / Gelifl tarihi: 07.11.2012 Received in revised form / Düzeltilerek Gelifl tarihi: 05.02.2013 Accepted / Kabul tarihi: 07.02.2013 GIDA (2013) 38 (2): 71-78 Research / Araflt›rma * Corresponding author / Yazışmalardan sorumlu yazar; farukg69@gmail.com, ✆ (+90) 328 861 2282, (+90) 328 861 2658 GD12083