This study was undertaken to evaluate the potential of fruit waste materials as source of natural antioxidant. The fruit peels including mango, guava and papaya peel were used in this study. The total phenolic content (TPC) was determined by Folin-Ciocalteu assay while antioxidant activities were determined by using ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging, ferric thiocynate (FTC) and thiobarbituric acid (TBA) assays. These antioxidant activities were compared to synthetic antioxidants, BHA/BHT combination and ascorbic acid. The results demonstrated that TPC ranged from 3.23 to 15.84 g GAE/100 g extract. Mango peels extract exhibited highest TPC compared to guava peel and papaya peel extract. In the FRAP assay, mango peel extract at 200 ppm, guava peel extract at 400 ppm and papaya peel extract at 1200 ppm, exhibited reducing power comparable to the permissible amount of BHA/BHT at 200 ppm. At concentration of 250 μg/ml, the DPPH radical scavenging activity of extracts and standards decreased significantly in the order of mango peel extract > guava peel extract > BHA/BHT > ascorbic acid > papaya peel extract. For the FTC assay, the antioxidant activity of mango peel extract was significantly higher than ascorbic acid, guava peel and papaya peel extract but lower than BHA/BHT while in the TBA assay, percentage inhibition of BHA/BHT and ascorbic acid were found to be higher than fruit peel extracts. The quantitative analysis for flavonoids showed the presence of catechin, epicatechin and kaempferol in the peel extracts.
The plant extract serves not only as a good source of bioactive compounds but also as natural pigment that can be applied as colourants in food and pharmaceutical products. The aim of this study were to determine the anthocyanin content of Garcinia mangostana peel extract (GMPE), Clitoria ternatea extract (CTE) and Syzigium cumini extract (SCE) in relation to their antioxidant activity and their colour properties. The antioxidant activities related to the phenolic constituents including anthocyanin content were determined based on the EC50 of DPPH radical scavenging activity and Ferric Reducing Antioxidant Power (FRAP) assay. The colour properties of the plant extracts were measured based on their degradation index (DI), indices of polymeric colour (PC) and colour density (CD). GMPE showed higher FRAP value and lower EC50 value which were 79.37 mmoles/g and 0.11 mg/ml, respectively, as compared to SCE extract with FRAP value, 25.66 mmoles/g and EC50 value, 0.22 mg/ml. Total monomeric anthocyanin (tmAcy) exhibited a strong correlation between FRAP assay (r2 = 0.998) and DPPH assay (r2 = 0.859). GMPE showed high CD (1.63 AU), moderate PC (0.18 AU) but low in DI (1.19 AU) while SCE exhibited low in CD (0.55 AU) and PC (0.07 AU) but moderate DI (1.26 AU). CTE exhibited high in DI (5.39 AU) and PC (0.19 AU) but moderate in CD (0.55). Hence, it can be concluded that colour pigment obtained from GMPE exhibited high antioxidant activity and better colour properties as compared to SCE and the strong correlation between tmAcy and two antioxidant activity assays which are FRAP and DPPH indicated that monomeric anthocyanin plays a major role in antioxidant activity of these plant extracts.
Bromelain is one of the vegetal proteases found in pineapple plant. It has numerous applications in food and pharmaceuticals. This review discussed different bromelain purification techniques which will assist in determining the effect of processing conditions on the purification efficacy. There are four purification techniques to be discussed, namely; reverse micellar system, aqueous two phase extraction, cation exchange chromatography and ammonium sulphate precipitation. Of the four techniques, cation exchange chromatography had shown the best bromelain purification technique with purification fold of 10.0 followed by reverse micellar system containing CTAB/ isooctane/ hexanol/ butanol, ATPE containing PEG polymer, ammonium sulphate precipitation and ATPE containing PEO-PPO-PEO with purification fold of 5.2, 4.0, 2.81 and 1.25, respectively.
This study was conducted on selected local herbs such as ulam raja (Cosmos caudatus), kesum (Polygonum minus), selom (Oenanthe javanica), pegaga (Centella asiatica) and curry leaves (Murraya koenigii) to investigate their antioxidative activities. The water extracts of the herbs were analysed for total phenolic content, reducing antioxidant power, ferric thiocyanate (FTC) and the thiobarbituric acid (TBA) test was also accried out. Polygonum minus showed the highest total phenolic content and reducing power among the herbs. Increasing the concentration of the extracts resulted in increased Fe3+ reducing antioxidant power for all the herbs. FTC and TBA tests on the extracts during seven days of storage showed that all the herbs extracts had the ability to reduce oxidation compared to the control (P < 0.05). From the FTC analysis, Murraya koenigii leaves was best in reducing the oxidation rate (67.67%) compared to the other herbs studied. Analysis of TBA showed that Centella asiatica extract had the highest antioxidant effect. However, both TBA and FTC analysis for these two herbs showed no significant difference (P >0.05) from Polygonum minus and butylated hydroxyanisole (BHT) a synthetic antioxidant. Correlation analysis showed positive correlations between amount of total phenolic content and reducing power (r = 0.75) and antioxidative activities (r = 0.58) in linoleic acid emulsion system. This shows that antioxidative activities of these Malaysian herbal plants especially Polygonum minus may be a potential source of natural antioxidants with similar characteristics to the synthetic antioxidant, BHT.
Pineapple waste is a by-product resulting from canning processing of pineapple that produce about 35% of fruit waste and lead to serious environmental pollution. Pineapple waste contains valuable nutrient components of simple sugar such as sucrose, glucose and fructose. Analysis of sugar content is important for further processing such as fermentation. The aim of this study was to determine the amount of sugar in different parts of pineapple waste (peel, core and crown) from variety N36. The selected pineapple waste for maturity indices 1, 2 and 3 was cut into small pieces before crushed in a food processor. The crushed waste was then filtered through muslin cloth followed by membrane filter 0.45μm to produce pineapple waste extract. Sugar content was determined using High Performance Liquid Chromatography. It was found that fructose content was significantly higher in core (2.24%) followed by peel (2.04%) and crown (0.87%). It was also found that glucose content was significantly higher in core (2.56%) followed by peel (2.18%) and crown (0.53%). Significant difference (p < 0.05) was found for sucrose content between pineapple core and peel extract with the value of 8.92% and 3.87%, respectively. However, sucrose was not detected in pineapple crown. It means that pineapple core extract had the highest values of fructose, glucose and sucrose compared to the other parts of pineapple waste extract. Besides, it was found that sucrose content was significantly higher in pineapple core for index 3 as compared to indices 1 and 2. Glucose and fructose was significantly higher in pineapple core for index 2 compared to indices 1 and 3.
The antioxidant capacity and total phenolic content of seeds of three types of pitaya namely Hylocereus polyrhizus, Hylocereus undatus and Selenicereus megalanthus and the fatty acid content of pitaya seeds oil were examined in this study. The ethanolic extracts of H. polyrhizus seeds showed significantly high (p
Herbal tea is widely consumed around the world because people believed that it contained high amount of antioxidant. However, usage of different maturity of the plants as raw materials could affect the antioxidant capacities in herbal tea. Hence, this paper reports the antioxidant activity of herbal tea prepared from Cosmos caudatus at different maturity namely young, mature and old leaves. The analyses carried out were total phenolic content (TPC), total flavonoid content (TFC), ferric reducing antioxidant power (FRAP) and DPPH (2-2-diphenyl- 1-picrylhydrazyl) radical scavenging assays. Based on the results obtained, herbal tea prepared from young leaves had significantly strong (p
Processing of soybeans to other products and consumption of soy products is increasing worldwide mainly due to acclaimed health benefits. Processing can alter soybean sensory appeal, nutritive value and potentially affect consumer health. Rhizopus oligosporus was used to ferment soybean for 3 days. The tempeh flour (TF) was produced form tempeh while defatted tempeh flour (DTF) was then produced from TF by immersing in hexane solvent while soy protein isolate (SPI) was prepared from DTF by using alkali and acid followed by neutralization treatment. In this study, nutritional properties and amino acid content of tempeh, TF, DTF and SPI were determined. Therefore, the objective of this study is was to evaluate the effect of each treatment on the chemical composition and amino acid content for all the samples. The results showed that the nutritional properties (total ash, moisture, crude fat, total carbohydrate and crude fibre) were reduced significantly (p < 0.05) except for protein content. Protein content was significantly (p < 0.05) increased by 50.5% in SPI. For amino acid content, the results obtained showed that SPI contain highest amount of essential and non-essential amino acid followed by DTF, Tempeh and TF. Glutamic acid was found to be the highest amino acid component in all samples. The evaluation from the results showed that SPI can be considered as potential functional food ingredients.
The aim of this study is to determine colour changes during storage and physico- chemical properties of peel, core and crown extracts of pineapple variety N36 for maturity indices of 1, 2 and 3. The L* (lightness), a* (redness) and b* (yellowness) values for peels increased significantly (p ≤ 0.05) at each maturity stage during seven days storage. pH of pineapple peel, core and crown extracts were in the range of 3.24 to 3.84. The titratable acidity, percentage of pulp and Total Soluble Solid (TSS) of pineapple peel, core and crown extracts were in the range of 0.16 to 0.36%, 1.37 to 2.91% and 1.4 to 5.3˚Brix, respectively. Fructose and glucose contents were significantly highest (p ≤ 0.05) in pineapple core extract followed by pineapple peel extract and pineapple crown extract for maturity index 2. Significant difference (p ≤ 0.05) was found in sucrose content between pineapple core and peel extracts with 8.92% and 3.87%, respectively for maturity index 3. However, sucrose was not detected in pineapple crown extract. Pineapple core extract was significantly higher (p ≤ 0.05) amount of total sugar content compared to pineapple peel and crown extracts for all maturity indices.
There are many factors influencing the stability and color variation of natural colorant anthocyanin and pH is among the most significant factor. This study aims to determine the stability of the anthocyanins in freeze-dried Hibiscus sabdariffa, Melastoma malabathricum and Ipomoea batatas in various acidic pH (pH 2.0, 2.5, 3.0, 3.5, 4.0 and 4.5). Total monomeric anthocyanin, degradation index, color density and percent polymeric color were analyzed to determine anthocyanins degradation and their color variations. Among the samples, H.sabdariffa contain the highest monomeric anthocyanins (163.3 mg/L) followed by M. malabathricum (49.9 mg/L) and the lowest is I.batatas (13.8 mg/L). Monomeric anthocyanins from I.batatas were found to be very stable and not affected by changes in pH than in H. sabdariffa and M. malabathricum. However, degradation index (DI) of H. sabdariffa was the lowest with value of 0.365 ± 0.049 at pH 3.5. The lowest percentage of polymeric color (4.94 ± 0.64) was also shown by H. sabdariffa at pH 2.5 and maintained a deep red color with increasing pH indicating higher color stability compared to M. malabathricum and I. batatas. Overall, natural pigment in H. sabdariffa was found to be the most stable in both monomeric anthocyanin content and chromaticity properties. These results provided information that will further proven the potential usage of H. sabdariffa, M. malabathricum and I. batatas as natural coloring agents to replace the synthetic colorant in food and beverage industries.
In the last decade, non-thermal processing for inactivating microorganisms has been developed in response to the worldwide interest for more fresh and improved quality of food products. Winter melon is a very perishable fruit, hence, processing into puree is a necessity. However application of heat in the production of puree could affect the nutritional values, thus, application of non thermal treatment in combination with preservation method is significant for this fruit. This study was conducted to evaluate the effect of non-thermal processing in combining with preservation method on antioxidant activity, level of key antioxidant groups (total phenolic and ascorbic acid content) and the color of winter melon puree. Total phenolic content (TPC) was measured using Folin-Ciocalteu reagent. Ascorbic acid (AA) was determined using 2,6-dichlorophenol-indophenol titration method. Antioxidant activity were determined using four antioxidant assays namely Ferric Reducing Antioxidant Potential (FRAP), Oxygen Radical Absorbance Capacity (ORAC), 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) and β-Carotene Bleaching Assays. For the TPC, puree with pH 3 (28.5±1.3 GAE/g fresh weight) exhibited high in TPC as compared to puree with pH 3.5 and unprocessed puree. In contrast, unprocessed puree contains significantly high ascorbic acid (AA) content (35.9 ± 1.8 mg/100 g fresh mass) as compared to pH 3.0 and pH 3.5 purees. In general, antioxidant activity for all assays of pH 3.0 and pH 3.5 purees were significantly higher (p