Determination of morphological, chemical and physiochemical properties and antioxidant capacities of pods from Lebanese carob (Ceratonia siliqua L.) varieties and identification of high-antioxidant candidates for food applications -

Abstract

Twenty-three carob varieties were collected from different regions of Lebanon and from different locations at the campus of the American University of Beirut. The morphological and chemical parameters including width, thickness, weight, number of seeds, moisture, ash, fat, protein, total dietary fiber, macrominerals (Na, P, Mg, Ca, K), microminerals (Cu, Zn, Mn, Fe), sucrose, glucose, fructose, and total phenols contents were determined. Further, the antioxidant capacities of the samples were determined by the 2,2-diphenyl1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and 2,2'-azinobis (3-ethylbenzthiazoline-6-sulphonic acid (ABTS) assays. The ranges of the samples were 11.8-26.5 g-pod for weight, 8.2-18.5 cm-pod for length, 1.5-3 cm-pod for width, 0.7-1.0 cm-pod for thickness, 7-13 seeds per pod for number of seeds, 11.0-13.2percent for moisture content, 2.4-4.7percent for ash content, 0.1 – 1.4 g-100 g for fat content and 3.4 - 6.5 g-100 g for protein content. Potassium was present at the highest concentration amongst the surveyed macrominerals and Fe was the most abundant micromineral. More specifically, the ranges for the microminerals were 0.13-0.58 mg-100g for Cu, 0.18-0.73 mg-100g for Mn, 0.23-0.56 mg-100g for Zn,1.77-15.34 mg-100g for Fe and the macrominerals’ ranges were 5.46-21.26 mg-100g for Na, 20.17-103.10 mg-100g for P, 25.92-100.10 mg-100g for Mg, 110.45-442.43 mg-100g for Ca and 1046.75-3992.50 mg-100g for K. The dietary fiber content of the samples varied between 4.7 and 8.2 g-100 g. Further, the samples displayed wide variations in their sugar contents with ranges of 50.3-140.9 g-kg for fructose, 21.3-96.3 g-kg for glucose and 109.9-358.3 g-kg for sucrose. The phenolic content of the samples ranged from 1.03 to 3.30 g Gallic Acid Equivalents- 100g. The antioxidant capacity of the samples as determined with FRAP was in the range of 1.0 and 3.38 µM Fe (II)-100g of carob; values for DPPH ranged from 0.03 to 0.55 mg-L and ABTS from 0.32 to 1.03 mg-L expressed as the caro