Flour and starch were prepared from six Thai banana cultivars: Kluai Hom, Kluai Khai, Kluai Lebmuenang, Kluai Namwa, Kluai Hakmuk and Kluai Hin, and their resistant starch (RS), in vitro starch digestibility and physico-chemical properties were determined. The RS content of the flour is 52.2-68.1%, with flour from Kluai Hin containing the highest amount of RS, followed by that from Kluai Hakmuk. The starch has a higher RS content (70.1-79.2%), the highest value coming from Kluai Hakmuk starch, followed by Kluai Hom starch. A significant linear relationship between apparent amylose and RS was observed. Interestingly, most of the flour showed a slower rate of in vitro starch digestibility than that of the starch, with Kluai Hin flour exhibiting the slowest rate, followed by Kluai Namwa. Rapid viscosity analysis showed significantly higher peak viscosity of the starch than the flour, the highest final and setback viscosity being obtained from Kluai Hin starch. Differential scanning calorimetry showed an endothermic transition enthalpy over a range of 17.4 J/g for Kluai Lebmuenang starch to 18.6 J/g for Kluai Hin starch. X-ray diffractograms of the starches exhibited a typical B-pattern with Kluai Hin showing the highest degree of relative crystallinity (31.3%) with a sharp peak at 5.5. The overall results seemed to indicate an effect of the BB genotype on the resistance of banana starch granules to enzymatic digestion due to amylose molecules and the crystallinity of amylopectin.
Antioxidant capacities were demonstrated between 13.25–86.00 mg vitamin C equivalent (VCE) per 100 g in 10 Northern foods and 4.63–176.71 mg VCE per 100 g in 10 Northeastern foods. The food that possessed the greatest antioxidant capacity was Sup ma khuea pro, and can be displayed from high to low as Kaeng phak seing da > Kaeng dok sa lae > Kaeng hed la ngok > Kaeng phak huan > Kaeng kae > Sup phak sa meg > Kaeng ka noon on > Kaeng dok ma rum> Kaeng pum > Kaeng naw mai bai ya nang> Lap tao > Sa yod ma kham > Kaeng sai bua > Kaeng phak seil > Kaeng om gai > Kaeng phak wan ban >Kaeng yhuak kluai > Kaeng dok phak plang > Pon pla krua ma noi. Total phenolic content in 100 g of Northern and Northeastern foods ranged from 48.42–225.70 and 15.63–157.62 mg gallic acid equivalent, respectively. Content of protein, fat, total dietary fiber and energy in 100 g were as follows; in Northern foods they ranged from 3.33–13.12, 0.55–3.02, 1.20–4.70 g and 24.67-96.65 Kcal, respectively. In Northeastern foods, protein, fat, total dietary fiber and energy varied from 1.69–5.05, 0.16–1.14, 0.90–3.50 g/100 g and 12.24–64.73 Kcal/100 g, respectively. Nutritionally, all 20 selected foods can be considered as low in fat and energy level.
Study was conducted on six varieties of three mangoes purchased from the local market as the ripe stage during the peak season in April. Six varieties namely Kaew, Nam Dok Mai, Nang Klang Wan, Okrong, Khieo Sawoey and Rad were prepared for alcohol insoluble solid (AIS). AIS content in Kaew was 2.2 percent which was the highest among the 6 varieties. Nam Dok Mai which is good for fresh consumption contain high pulp content, and AIS value in Nam Dok Mai and Okrong were low as 1.4 and 1.3 percent respectively. Pectin content in AIS was 16-20 percent in all six varieties. Amonium oxalate soluble pectin (ASP) and hydrochloric acid-soluble pectin (HSP) which refer to the hardness of fruit were high in Kaew and low in Nam Dok Mai, Okrong and Nang Klang Wan. Average molecular weight of pectin in Kaew was rather low compare with other varieties. Average molecular weight of pectin of ASP is in the range of 20,000-200,000 and variation occurred among varieties.
Samples from 29 starchy foods and 11 cultivars of banana were analyzed for their contents of resistant starch (RS), digestible starch and total starch, as well as the in vitro starch digestibility. The RS analysis was based on a-amylase and amyloglucosidase hydrolysis followed by colorimetric assay of the glucose released. The results showed that the main RS sources were found in the legume group (10.3 ± 1.2% to 22.9 ± 0.0%), glass noodle products (9.1 ± 0.8% to 11.3 ± 1.5%) and bananas (52.2 ± 4.1% to 61.4 ± 2.3%). For the rice group, the effect of processing methods on the retrograded RS formation was investigated. Khanomjean produced with fermentation had a higher RS content (8.5 ± 1.1%) than that of the cooked white rice of the high-amylose cultivar. With the rice snacks, the process for puffing kaotung and kaokreupvor by frying and roasting produced a higher RS content (2.6 ± 0.0% and 2.9 ± 0.3%, respectively) than in the raw samples. Among the rice noodles, vermicelli contained a higher RS content than the others. Moreover, a gelatinization effect on the RS contents was clearly evident, with the gelatinized cassava starch (2.2 ± 0.0%) having a lower RS content than the commercial starch (44.6 ± 0.3%), whereas the commercial RS content was high (58.5%). Finally, the test on in vitro starch digestibility showed that the legume samples, particularly with red beans, had the lowest rate of starch digestibility compared to the other samples.
The objective of this study was to produce type-III resistant starch (RS-III) by the pullulanase reaction. A 10% (dry weight) cassava starch suspension adjusted to either pH 5.0 or 5.5 was gelatinized at 120°C for 30 min. Pullulanase of 3%, 5% and 10% (v/w) of starch weight was added to debranch the starch and placed in a water bath of 50°C for hydrolysis periods of 2 to 24 h. The resulting starch was retrograded by a cooling of 4°C and dried by hot air at 40°C. The starch products were determined for reducing sugars, amylose, RS-III, and for in vitro starch digestibility, as well as changes in the structural properties. The results showed that the reducing sugars obtained with any treatments tended to increase with the length of the reaction time. The starches treated at pH 5.0 or pH 5.5 and hydrolyzed with 5% pullulanase for 8 h had significantly higher reducing sugars of 1.57±0.1 and 3.43±1.2 g/100g, respectively, than the initial content (0.62±0.0 g/100g) and showed more effect than the 3% pullulanase. At pH 5.0, the starches hydrolyzed with 3 and 5% pullulanase for 8 h gave a higher amylose content than those treated at pH 5.5. An acidity effect of pH 5.0 related to the content of RS-III formed over the reaction time of 8 h, showing a high value of 12.8±1.3 and 17.4±1.5 g/100g for the 3% and 5% pullulanase, respectively. When the starch was reacted with 10% pullulanase for 8, 16 and 24 h, a significant increase in the RS-III from the gelatinized cassava starch (9.2 ± 0.0 g/100g) resulted with a value of 41.2±3.5, 45.8±2.5 and 42.5±1.3 g/100g, respectively. This result also related to the in vitro starch digestibility of the RS-III samples being about 20 to 30 % slower than the starting starch after 90 min of amylase digestion. Finally, the structural changes to the type-B crystallites via type-C and a mixture of the Vtype, as well as the scanning electron micrographs of the RS-III could confirm its property of slow enzymatic digestion. Thus, conditions of pH 5.0, hydrolysis of 10% pullulanase for 24 h and hot air drying were suitable for partially debranching amylopectin of the cassava starch, consequently providing small linear fragments and small clusters of the amylopectin for recrystallization and formation of the RS-III.
Water soluble pectin (WSP) in an alcohol insoluble solid (AIS) of mango “Kaew”, which is exclusively used in processing, increased with maturation. Hydrochloric acid soluble pectin (HSP) decreased. Ammonium oxalate soluble pectin (ASP) did not exhibit a regular pattern. Average molecular weight (MW) of all soluble pectins decreased as the mangoes matured to the overripe stages. Between the half-ripe and ripe stages, average MW decreased significantly in both WSP and ASP. Average MW values for HSP declined gradually as maturation proceeded.
