Investigation of physicochemical properties of artichoke (Cynara cardunculus L. Var. Scolymus) drıed by different methods and mathematical modelling of drying characteristics


Thesis Type: Postgraduate

Institution Of The Thesis: Bursa Uludağ University, ZİRAAT FAKÜLTESİ, GIDA MÜHENDİSLİĞİ, Turkey

Approval Date: 2019

Thesis Language: Turkish

Student: KÜBRA GİZEM ŞAHİN

Supervisor: Ömer Utku Çopur

Abstract:

In the current study it was aimed to investigate the physiological changes and antioxidant activites of BayrampaĢa artichoke (Cynara cardunculus var. scolymus L.) cultivar that was dried as slices by applying two different pretreatments (boiling and steaming) and three different drying methods (convenctional, microwave and vacuum drying). Titration acidity, pH anf total dry matter analyzes were carried on fresh artichoke hearts. Also, antioxidant capacity (DPPH, FRAP and CUPRAC), total phenolic compounds and color analyzes were measured in both fresh artichoke hearts and dried artichokes, and mathematical modeling was conducted in dried artichoke heart samples. Titration acidity, pH and total dry matter content were determined as 0,05 g/100 g, 4,3 and 14,09 g/100 g, respectively. As a result of the color analysis of dried artichokes, it was found that L value were between 28,35 – 46,25, a value of 2,27 – 7,85 and b value of 11,84 – 25,51, respectively. According to the antioxidant analysis methods, the amount of antioxidants in dried artichoke samples was observed to be considerably lower than fresh artichoke heart. The antioxidant activities of the dried artichoke heart were between 5,46 – 6,59 μmol trolox/g dry weight in DPPH method, 1,40 – 66,98 μmol trolox in CUPRAC method and 1,13 – 20,78 μmol trolox/g dry weight in FRAP method. The total phenolic content of the dried artichoke samples was determined between 64,54 – 160,24 mg gallic acid/g dry weight. Page and Modified Page models are the best fitted drying methods with the highest value of R2 (both of them 0,9989) and the lowest values of RMSE (0,0023 for both) and x2 (0,00007 – 0,00007) compared to other models.