Antioxidant activity and nutritional quality of traditional red-grained rice varieties containing proanthocyanidins

Proanthocyanidin-containing rice varieties have been rarely reported. Antioxidant capacity, major antioxidant components, and nutritional parameters of eight traditional red-grained rice varieties containing proanthocyanidins grown in Sri Lanka were investigated. The tested traditional red varieties, on the average, had over sevenfold higher both total antioxidant capacity and phenolic content than three light brown-grained new-improved rice varieties. Major antioxidant phenolic compounds identified in this study included proanthocyanidins, phenolic acids and γ-oryzanols (ferulic acid derivatives). Proanthocyanidins were detected only in the traditional red varieties, but not found in new-improved ones. Most traditional red varieties also contained significantly higher levels of protein with well balanced amino acids and higher contents of fat, fibre and vitamin E (tocopherols and tocotrienols) than the new-improved ones. Great variations in antioxidant capacity, major phenolics, and nutritional parameters were observed among different rice varieties. These Sri Lankan traditional red-grained rice varieties containing proanthocyanidins may be used as important genetic sources for rice breeding.

Comparative analysis of nutritional quality of five different cultivars of sweet potatoes (Ipomea batatas (L) Lam) in Sri Lanka

Nutritional attributes of flours obtained from five different cultivars of sweet potato roots commonly available in Sri Lanka showed significant differences in the tested parameters. The starch level ranged between 33% and 64% on the dry basis and the extractability from fresh tubers was governed by the quantity of starch. The crude fiber level ranged between 2.1% and 13.6% on dry basis and the highest level was observed in swp7 (CARI 273) and resistant starch ranged from 14.2% to 17.2%. Higher percentage of resistant starch from total starch was found in Wariyapola red (swp1) cultivar resulting in lower digestion level while higher levels of digestion was evident in cultivars with lower levels of resistant starch with high level of total starch. Low levels of calcium and significant levels of iron were found in the five cultivars studied. Crude protein level was in the range of 1.2–3.3% on dry basis and trypsin inhibitor activity level (TIA) was significantly different (P > 0.05) in the cultivars studied while heating resulted in a significantly high reduction in the TIA level than in unheated condition. Polygonal or round shaped starch granules were in the range of 16.8–23.5 μm and low level of starch digestion was shown in cultivars containing larger granules. Total amylose content lies in the range 15.4–19.6% and cultivars having higher percentage of amylose showed higher level of in vitro pancreatic digestion (Pallepola [swp4] and swp7). The starch digestibility of sweet potato flour was in the range of 36–55% and the highest digestion was observed in swp7. Orange fleshed cultivars (swp4 and swp7) were comparatively rich in nutrients and digestibility than the other three studied cultivars.

L-Theanine: A Unique Functional Amino Acid in Tea (Camellia sinensis L.) With Multiple Health Benefits and Food Applications

Tea (Camellia sinensis L.) is a very popular health drink and has attracted increasing attention in recent years due to its various bioactive substances. Among them, L-theanine, a unique free amino acid, is one of the most important substances in tea and endows tea with a special flavor. Moreover, L-theanine is also a bioactive compound with plenty of health benefits, including antioxidant, anti-inflammatory, neuroprotective, anticancer, metabolic regulatory, cardiovascular protective, liver and kidney protective, immune regulatory, and anti-obesity effects. Due to the unique characteristics and beneficial functions, L-theanine has potential applications in the development of functional foods. This review summarized the influencing factors of L-theanine content in teas, the main health benefits and related molecular mechanisms of L-theanine, and its applications in food, understanding of which can provide updated information for the further research of L-theanine.

Effect of fertiliser on functional properties of flour from four rice varieties grown in Sri Lanka

BACKGROUND

Fertiliser is an essential agro-chemical input in modern rice farming. Fertiliser affects the grain quality and yield of rice. Although much research has been carried out to investigate the influence of fertiliser (recommended NPK addition) on yield and quality of rice grain, little is known about the effect of fertiliser on thermal, pasting, gelling and retrogradation properties of rice flour. The aim of this study was to investigate the influence of recommended fertilisation on functional properties of rice flour from four popular high yielding rice varieties grown in Sri Lanka.

RESULTS

Fertiliser (recommended NPK addition) increased the protein content but reduced the apparent amylose content in rice flour except in BG 357. Swelling power and amylose leaching were decreased by fertilizer. [corrected] Pasting onset temperature, cold paste viscosity and setback were increased but peak viscosity and granular breakdown decreased. In response to the fertiliser application, gelatinisation peak temperature was reduced in all varieties except BG 300. However, compared to pasting properties, gelatinisation parameters were not much affected by fertilisation. The extent of amylopectin retrogradation was decreased by fertiliser in BG 305 and BG 352 but unchanged in the other two varieties. Except in BG 305, fertiliser reduced the gel hardness of rice flour but increased the gel cohesiveness.

CONCLUSION

It is apparent that the increased protein and reduced amylose content caused by fertiliser affect the functional properties of rice flour.

Effect of parboiling on the formation of resistant starch, digestibility and functional properties of rice flour from different varieties grown in Sri Lanka

BACKGROUND

Hydrothermal treatment used in parboiling could induce formation of novel starch properties having potential food applications. In the current work, functional, digestible and retrogradation properties of flour from non-parboiled and steamed parboiled six rice varieties with high amylose content of around 30% but differing in length and width ratio were investigated and compared.

RESULTS

The parboiling process reduced swelling volume and amylose leaching in all tested varieties. Among the varieties studied, the resistant starch content ranged from 1.6% in AT 306 to 0.46% in BG 357. Parboiling reduced the resistant starch content in AT 306 by about 50%, but it did not significantly affect the resistant starch content of the other varieties. The amylose-lipid complex remained unchanged after parboiling. Amylopectin retrogradation was not observed in parboiled rice. Amylose retrogradation was not seen except for AT 306. Pasting behaviour of parboiled rice flours showed high pasting stability and low setback. Flours were more susceptible to enzymatic hydrolysis after parboiling. Partial gelatinisation during parboiling was sufficient to produce grains with excellent milling quality showing a head rice recovery that ranged from 98% to 100% among the varieties studied.

CONCLUSION

Degree of gelatinisation is the most important factor that determines the high head rice recovery. High pasting stability and low setback of flour of parboiled rice indicate some potential food applications.

Comparison of the Phenolic Profiles of Soaked and Germinated Peanut Cultivars via UPLC-QTOF-MS

Diverse peanut varieties are widely cultivated in China. However, few studies have investigated the effects of germination on the phenolic profiles and antioxidant activities of specific Chinese peanut cultivars. Therefore, this study was conducted to evaluate the effects of germination on total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity, and phenolic profiles of seven peanut cultivars in China. The TPC, TFC, and antioxidant activities were determined by spectrophotometry, while phenolic profiles were analyzed by using ultra-high performance liquid chromatography coupled with quadrupole/time-of-flight mass spectrometry (UPLC-QTOF-MS). The results found that germination significantly increased TPC, TFC, and antioxidant activity. Antioxidant activity was found to be closely related to TPC in germinated peanut extracts, which indicates that phenolics are the main contributors of antioxidants in germinated peanuts. In addition, germination induced significant changes in polyphenolic profiles. In the analyzed samples, 36 phenolic compounds were identified in which most were flavonoids. Overall, these findings highlight that germinated peanuts can be a good natural source of natural antioxidants for human consumption and functional food development.

Effect of heat-moisture treatment on digestibility of different cultivars of sweet potato (Ipomea batatas (L.) Lam) starch

Different heat-moisture levels were applied to native starches from different cultivars of sweet potatoes available in Sri Lanka (Wariyapola red, Wariyapola white, Pallepola variety, Malaysian variety and CARI 273) to study the digestibility level. Samples were treated with 20, 25, and 30% moisture at 85°C and 120°C for 6 h and in vitro starch digestibility was tested with porcine pancreatin enzyme. A range of 19.3-23.5% digestibility was shown by the native starches with no significant difference (P < 0.05). Significant changes were observed in the digestibility level of the hydrothermally modified starches and the moisture content showed a positive impact on the digestibility. Heat-moisture treatment at 85°C brought an overall increase in digestibility and temperature beyond 85°C had a negative impact. No significant difference (P < 0.05) in the digestibility was observed with 20% and 25% moisture at 85°C and increased level were seen at 85°C and 30% moisture.

Detection of Ni, Cd, and Cu in green leafy vegetables collected from different cultivation areas in and around Colombo District, Sri Lanka

Five types of green leafy vegetables ["Kankun" (Ipomoea aquatica), "Mukunuwenna" (Alternanthera sessilis), "Thampala" (Amaranthus viridis), "Nivithi" (Basella alba), and "Kohila leaves" (Lasia spinosa)] were randomly collected from six different locations (Wellampitiya, Kolonnawa, Kottawa, Piliyandala, Bandaragama, and Kahathuduwa) in and around Colombo District, Sri Lanka, and subjected to analysis of three heavy metals [nickel (Ni), cadmium (Cd), and copper (Cu)] by atomic absorption spectrometry. Soils from green leafy vegetable cultivation lands and irrigated water were also tested. The average concentrations of heavy metals Ni, Cd, and Cu in soils were 51.5 ± 45.5, 1.4 ± 1.1, and 66.5 ± 59.5 mg kg(-1), respectively. The highest Ni contamination was detected in the irrigated water samples from Wellampitiya (2.02 mg L(-1)) followed by Kolonnawa (1.02 mg L(-1)) and Kahathuduwa (0.25 mg L(-1)) areas. This has exceeded the WHO/FAO guideline (0.2 mg L(-1)). However, Cd and Cu contents in all tested irrigated water samples were well below the detection limits. Significant differences were observed in Ni, Cd, and Cu levels, between both production sites and green leafy vegetables analyzed (P < 0.05). The mean concentrations (mg kg(-1), dry weight basis) of heavy metals in all green leafy vegetable samples collected from six areas varied as 0.23 ± 0.15 for Cd, 12.60 ± 9.01 for Cu, and 7.62 ± 8.41 for Ni. Maximum Ni, Cd, and Cu contaminations were found in the green leafy vegetables collected from Kolonnawa area. Among the green leafy vegetables analyzed, "Kohila leaves" have the highest tendency to accumulate Ni, Cd, and Cu from the environment.