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Process optimization, antioxidant activity and sensory characteristics of green tea made from young fragrant rice leaves cultivar Damgatondam
(2019-01-01)
Uthai, N.
;
Thamakorn, P.
;
Kerdpiboon, S.
;
Nokkoul, R.
Green tea was made from one-month old leaves of the Thai upland black waxy rice cultivar Damgatondam (DGTD), which has a pleasant smell of jasmine. The objective was to determine the optimum process required to produce green tea that is acceptableto consumers and has health benefits. The processing conditions were steaming at 98 ± 2°C for 30, 45, 60 75, 90 or 105 sec then pan roasting at 70 ± 2°C for 5, 10, 15, 20, 25 or 30 min and finally tray drying by using electrical cabinet tray dryer at 60 ± 2°C for 30, 45, 60 or 90 min. Brewed samples were compared to brewed samples of seven commercially available Camellia sinensis tea products by descriptive analysis with 10 trained panelists. The highest quality of DGTD tea was: steaming at 98 ± 2°C for 60 sec, which completely inactivated peroxidase enzymes and preserved the green color, followed by pan roasting at 70 ± 2°C for 30 min and tray drying at 60 ± 2°C for 90 min in order to achieve a moisture content of less than 5%. The proximate analysis showed the DGTD tea prepared by the above method had: 3.77% moisture content, 7.94% ash, 22.59% crude fiber, 2.58% fat and 17.73% protein. Moreover, Ca, Mg, K, Fe, Mn and Na were 3400, 3200, 20400, 66.4, 139.1 and 113.8 mg/kg, respectively. It was found that protein, fat, crude fiber, ash, Mg, K and Na contents in DGTD tea, were higher than levels in tea from Camellia sinensis. Total phenolic content of DGTD tea was 9.53 mg GAE/g and antioxidant activity was 357.52 mM TE/g by Ferric reducing antioxidant power ( FRAP) , l34.08 mM TE/g by 2,2 diphenyl-1-picrylhydrazyl assay (DPPH) and 108.89 mM TE/g by 2,2'-azino-bis ( 3-ethylbenzothiazo line-6-sulphonic acid) ( ABTS) . The descriptive analysis of trained panels identified 11 particular attributes of DGTD tea, consisting of yellowness, clearness, tea odor, hay odor, green odor, seaweed odor, jasmine rice odor, tea flavor, seaweed flavor, bitter taste and astringent taste. The descriptive analysis showed that the DGTD tea was less bitter and astringent than the Camellia sinensis tea and its jasmine odor was positively accepted.
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Luffa sponge offsets the negative effects of aeration on bacterial cellulose production
(2016-12-01)
Krusong, W.
;
Kerdpiboon, S.
;
Pornpukdeewattana, S.
;
Jindaprasert, A.
Aims: To offset the negative effects of aeration on bacterial cellulose (BC) production by acetic acid bacteria using enmeshed cellulose microfibrils (CM) on luffa sponge matrices (LSM). Methods and Results: The CM were enmeshed on LSM (LSM-CM). The optimal amount of LSM-CM was determined for BC production under aerated conditions. Without LSM-CM, no BC was produced in seven out of nine production cycles at the highest aeration rate (9 l min−1). However, with 0·5% LSM-CM and an aeration rate of 3 l min−1, a satisfactory oxygen transfer coefficient was achieved, and also a good yield of BC (5·24 g l−1). Moreover, the LSM-CM was able to be recycled through nine consecutive BC production cycles. The highest BC yields (from 5·8 ± 0·4 to 6·6 ± 0·4 g l−1) were associated with high bacterial biomass and this was confirmed by scanning electron microscopy. Conclusions: We confirm that LSM-CM works well as a starter. Microenvironments low in dissolved oxygen within the matrices of LSM-CM are important for BC production under aeration conditions. Significance and Impact of the Study: The LSM-CM provides a microenvironment which offsets the negative effects of aeration on BC production. A sustainable, economic process for mass BC production is described using recycled LSM-CM with aeration.
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Influence of calcium chloride in the high temperature acetification by strain Acetobacter aceti WK for vinegar
(2015-11-01)
Krusong, W.
;
Kerdpiboon, S.
;
Jindaprasert, A.
;
Yaiyen, S.
;
Pornpukdeewatana, S.
Aims: To improve the thermotolerant properties (TTP) of acetic acid bacteria (AAB) cells for high temperature acetification. Methods and Results: At high temperature (36 ± 1°C), the acetification rate (ETA) is usually lower than at 30 ± 1°C. The addition of 0·15% calcium chloride (CaCl<inf>2</inf>) may decrease the negative effect of the increase of temperature from 30 ± 1°C to 36 ± 1°C on the ETA. The effect of CaCl<inf>2</inf> on the thermotolerant properties of acetic acid bacteria cells was investigated. The CaCl<inf>2</inf> increased the content of phospholipids (phosphotidylcholine and phosphatidylglycerol), fatty acids (cis-vaccenic acid, palmitic acid and myristic acid) and the activities of membrane-bound enzymes involved in acetification, alcohol dehydrogenase and aldehyde dehydrogenase. Transmission electron microscope images revealed a more compact cell wall with CaCl<inf>2</inf>. Process consistency at 36 ± 1°C was tested in nine sequential acetification cycles using 0·15% (w/v) CaCl<inf>2</inf>. High ETAs (9·33 ± 0·6; 8·67 ± 0·8 and 9·67 ± 0·7 g l-1 day-1) were obtained during the last three cycles. Conclusions: The results confirm that changes of the content of lipid, activities of membrane-bound enzymes and cell-wall thickness occurred with added CaCl<inf>2</inf>. Significance and Impact of the Study: High temperature acetification (HTA) with additions of CaCl<inf>2</inf> was investigated. Significant reductions in the overall production costs result from lower cooling costs associated with HTA.

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