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Effects of steaming and drying on quality and antioxidant activity of white-fleshed sweet potato powder (Ipomoea batatas)
(2024-01-01)
Thuy, N. M.
;
Giau, T. N.
;
Hao, H. V.
;
Dung, N. C.
;
Tai, N. V.
White-fleshed sweet potatoes (WFSP) are rich sources of polyphenols. The flesh of PFSP contains total polyphenol content (TPC) at 1.52 mgGAE/g fresh weight. The raw material’s total free radical scavenging capacity was estimated (at 42.4% DPPH). The inactivation of peroxidase (POD) and polyphenol oxidase (PPO), the breakdown of total phenolic compounds, antioxidant activity, and the whiteness of WFSP were evaluated during steam blanching from 0 to 9 minutes. Steam blanching time from 7 to 9 minutes at boiling temperature (100ºC) inactivated most of the POD and PPO enzymes (71.2% and 70.5%, respectively), thus TPC and antioxidant activity remains high, resulting in a bright white product. After 7 minutes of blanching, drying experiments of WFSP slices were conducted at air temperatures of 50 to 80ºC. The best alternative for describing and understanding the drying of WFSP slices was the Page model. In the temperature’s ranges, the values of the moisture diffusivity (De f f) and activation energy are obtained from 3.059×10−12 to 5.095×10−12 m2 /s and 14.93 kJ/mol, respectively. The drying temperature of 70ºC for 10 hours was suitable for producing WFSP powder with low water activity (0.5) and moisture content (6.5%), high TPC and antioxidant activity, and low specific energy consumption. These results suggested that the WFSP powder exhibited potential as a nutraceutical ingredient product.
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Impact of ultrasound-assisted process on enzymatic extraction of polyphenols from purple rice bran in Vietnam: Experimental kinetics and innovative artificial approach
(2024-01-01)
Loan, L. T.K.
;
Vinh, B. T.
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Tai, N. V.
Ultrasound waves is one of the emerging innovative techniques, that widely applied to assist the extraction process. Besides, enzymatic extraction process also considered as green technology. In addition, in Asia country, especially in Vietnam, the rice bran is abundant, which contained many health benefits compounds. This study is aimed to investigate the effect of power of ultrasound (20-100%) on the kinetic of recovery yield (RY, %) and total polyphenol content (TPC, mgGAE/g) in the extract. The statistical and artificial analysis were applied to study the behavior of extraction process. Among 5 statistical models, the first-order model showed the best prediction the extraction characteristics of ultrasound-assisted enzymatic extraction process under different levels of sonication waves (R2 > 99%). Artificial statistical analysis with 2 inputs (sonication power and extraction time) and two outputs (RY and TPC), also reflected more quick and powerful for prediction with the large and complex dataset with the structure of 2-5-2. The fitting between actual and predicted data set of statistical and artificial model presented that the artificial remained more advantage for describing the extraction process than the first-order model. Further studies could consider this approach for using in other extraction process in other kinds of materials.
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Process of foam-mat drying of purple rice bran extract and evaluation of product properties
(2023-01-01)
Loan, L. T.K.
;
Tai, N. V.
The present study examined the process of foam-mat drying “Cám” purple rice bran extract, including optimization foaming conditions and effect of drying temperatures on the drying behaviours and powder's qualities. The egg album and xanthan gum at different levels were used as foaming agents, which further optimizied by the response surface methodology. The optmial foam was dried at four levels of temperature (50-80oC). Moisture content was further recorded every 30 minutes. Four common emperical models were applied for predicting the pattern of moisture content. Under the effect of heat treatment, the final qualities of Cám purple rice bran foam-mat dried powder were determined. The results showed that when egg albumin and xanthan gum were used, 12.04% and 0.337% could maximize foam expansion and stability. These conditions could facilitate the efficiency of the drying process. Moreover, among the four models, the Page model showed the best fit for predicting the change in moisture ratio. The effective diffusivity and activation energy were from 6.73 x 10-10 to 1.66 x 10-9 m2/s and 22.72 kJ/mol, respectively. The study also revaled that at temperature of 70oC, the product could maintain high antioxidant proper conditions for storage and high acceptance by consumer.

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