Anhydrous sodium sulfate

Commercial O. vulgare essential oil (CO) was purchased from Botanicessence (Product of Spain) (Bangkok, Thailand). Carvacrol, α-tocopherol, 2,2′-diphenyl-1-picrylhydrazyl (DPPH), 2,4,6, tripyridyl-s-triazine (TPTZ), hydrochloric acid (HCl), acetic acid (CH₃COOH), linoleic acid, hyaluronidase from bovine testes, sodium chloride (NaCl), collagenase from Clostridium histolyticum, N-[3-(2-furyl)acryloyl]-Leu-Gly-Pro-Ala (FALGPA), elastase from porcine pancreas, N-succinyl-Ala-Ala-Ala-p-nitroanilide (AAAVPN), sodium phosphate monobasic dihydrate (NaH₂PO₄.2H₂O), and sodium phosphate dibasic dihydrate (Na₂HPO₄.2H₂O) were purchased from Sigma-Aldrich (St. Louis, MO, USA); α-Ascorbic acid was purchased from Asia Pacific Specialty Chemicals Limited (New South Wales, Australia). Anhydrous sodium sulfate (Na₂SO₄), ferric chloride hexahydrate (FeCl₃.6H₂O), ferrous sulphate heptahydrate (FeSO₄.7H₂O), and ammonium thiocyanate (NH₄SCN) were purchased from Loba Chemie (Boisar, Tarapur, India). Bovine serum albumin was purchased from Merck (Darmstadt, Germany). Tricine was purchased from Bio-Rad Laboratories (Richmond, CA, USA). Sodium acetate trihydrate (CH₃COONa.3H₂O), calcium chloride dihydrate (CaCl₂.2H₂O), sodium hydroxide (NaOH), dimethyl sulfoxide (DMSO), dichloromethane, methanol, and ethanol were analytical grade and purchased from RCI Labscan Co., Ltd. (Bangkok, Thailand).

The β‐carotene was determined as described by Perez‐Lopez (2010 (link)) and Association of Official Agricultural Chemists (AOAC) (1980 ) with some modifications. Five grams (5 g) of the sample (raw, pickle, and relish products) in 1% butylated hydroxytoluene (BHT) (LOBA Chemie, India) was homogenized using a blender (Moulinex, China) for 5 min and placed into the falcon tube (BR Biochem, India). The homogenate was treated with 30 ml of solvent (50% hexane:25% acetone:25% ethanol) (LOBA Chemie, India) and then centrifuged at 4000 rpm at ambient temperature for 10 min. The supernatant was collected and filtered using Whatman No. 1 filter paper (Whatman International Ltd., India), and then was re‐extracted two times until the residue was colorless. The supernatant was combined, and the volume was recorded. The supernatant was saponified with 40% potassium hydroxide (LOBA Chemie, India) and left at ambient temperature for 12 h. The mixture was then transferred into the separating funnel and treated with the same volume of 10% w/v sodium chloride (LOBA Chemie, India) for removing moisture. The mixture was then shaken vigorously, and the upper phase was collected and dried over anhydrous sodium sulfate (LOBA Chemie, India). The β‐carotene content was estimated based on the standard curve of β‐carotene, and the result was expressed as mg/100 g (wet basis).