Physicochemical Characteristics and Antioxidant activities of Sikhye Made with Pigmented Rice

The study was conducted with the aim of processing and developing ready to cook jackfruit to evaluate their nutritional and sensory quality attributes. In this study, green tender jack fruits were harvested from 60 to 70 days after synthesis. Then the fruits were washed, peeled and cut into slices. The slices were treated by dipping into different solutions for each treatments viz. control (T1), 0.5% salt solution (T2), 0.2% citric acid solution (T3), 1000 ppm potassium metabisulfite (KMS) (T4), 1000 ppm KMS + 0.5% salt (T5), 1000 ppm KMS + 0.2% citric acid (T6), 0.5% salt + 0.2% citric acid (T7) and 1000 ppm KMS+ 0.2% citric acid+ 0.5% salt (T8). Then the treated sliced was steam blanched at 85°C temperature for 8 min. The roasted beef spices were mixed and then dried at 50°C, 60°C and 70°C temperature owing to preparation of ready to cook. Results revealed that ready to cook dried at 50°C, 60°C and 70°C temperature took 72 hrs, 48 hrs and 36 hrs respectively. Low potassium metabisulfite residue was observed with increasing blanching time and drying temperature. The physicochemical characteristics, phytochemical and antioxidant activities were retained more and the highest sensory score was obtained at 60°C temperature. The marketable life of the RTC jackfruit could be extended to more than 6 months. However, the findings suggest that green tender jackfruit treated with 1000 ppm KMS, blanched for 8 min and dried at 60°C is a quick and healthy option in terms of good marketable life, nutritional and sensory quality attributes. Keywords:Tender jackfruit, ready to cook, nutritional quality, sensory attributes, marketable life

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Comparison of hot water and methanol extraction combined with ultrasonic pretreatment on antioxidant properties of two pigmented rice cultivars

Food Research ◽

10.26656/fr.2017.4(2).330 ◽

2019 ◽

Vol 4 (2) ◽

pp. 547-556

Author(s):

U. Tobgay ◽

P. Boonyanuphong ◽

P. Meunprasertdee

Keyword(s):

Conventional Method ◽

Antioxidant Activities ◽

Hot Water ◽

Red Rice ◽

Rice Varieties ◽

Ultrasonic Pretreatment ◽

Phenolic Contents ◽

Pigmented Rice ◽

Methanol Extraction ◽

Glutinous Rice

Pigmented rice is considered as the good source of phytochemicals which contains more phenolic contents and higher antioxidant activities compared with non-pigmented rice. However, those phytochemicals are normally extracted using inorganic solvent, using water was rarely found. This study was aimed to compare extraction methods on antioxidant contents and activities of two types of Thai pigmented rice (black glutinous rice and red non-glutinous rice). Pigmented rice was extracted either conventional method alone or a combination of ultrasonic plus conventional method with different solvents (methanol and hot water). Phenolic contents were analyzed by spectrophotometric assay and high-performance liquid chromatography (HPLC). Antioxidant activities were investigated by radical scavenging capacity (ABTS and DPPH). The results showed that ultrasonic pretreatment significantly enhanced the total phenolic, flavonoid, anthocyanin contents and higher antioxidant activities compared with conventional extraction irrespective of solvents and rice varieties. Ultrasonic methanol (UM) extraction proved to extract significant higher content of all the compounds analyzed in both the rice varieties. In contrast, hot water (HW) extracts exhibited the lowest amount of bioactive compounds. However, there was no significant difference between methanol extraction alone and ultrasonic pretreatment with hot water extract on antioxidant contents for black glutinous rice. The contents of individual anthocyanins and flavonoids (cyanidin 3-O-glucoside, peonidin 3-O-glucoside, and quercetin) were significantly increased with ultrasonic pretreatment compare to the conventional method in black glutinous rice while failed to detect the red rice variety. The black glutinous rice contained significantly higher contents of all analyzed compounds and antioxidant activities than red rice. In conclusions, our results demonstrated that ultrasonic pretreatment significantly enhanced antioxidant extraction with higher activities compared with conventional extraction irrespective of solvents and rice varieties. Furthermore, the efficiency of ultrasonic together with hot water extraction was almost equal to methanol extraction which was the one effective solvent for extracting antioxidant.

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