Siti Hajar Ahmad

Physico-chemical properties of Moringa oleifera seed oil enzymatically interesterified with palm stearin and palm kernel oil and its potential application in food

BACKGROUND High oleic acid Moringa oleifera seed oil (MoO) has been rarely applied in food products due to the low melting point and lack of plasticity. Enzymatic interesterification (EIE) of MoO with palm stearin (PS) and palm kernel oil (PKO) could yield harder fat stocks that may impart desirable nutritional and physical properties. RESULTS Blends of MoO and PS or PKO were examined for triacylglycerol (TAG) composition, thermal properties and solid fat content (SFC). EIE caused rearrangement of TAGs, reduction of U3 and increase of U2 S in MoO/PS blends while reduction of U3 and S3 following increase of S2 U and U2 S in MoO/PKO blends (U, unsaturated and S, saturated fatty acids). SFC measurements revealed a wide range of plasticity, enhancements of spreadability, mouthfeel and cooling effect for interesterified MoO/PS, indicating the possible application of these blends in margarines. However, interesterified MoO/PKO was not suitable in margarine application, while ice-cream may be formulated from these blends. A soft margarine formulated from MoO/PS 70:30 revealed high oxidative stability during 8 weeks storage with no significant changes in peroxide and p-anisidine values. CONCLUSION EIE of fats with MoO allowed nutritional and oxidative stable plastic fats to be obtained, suitable for possible use in industrial food applications.

Influence of Oil Palm Empty Fruit Bunch Biochar on Floodwater pH and Yield Components of Rice Cultivated on Acid Sulphate Soil under Rice Intensification Practices

Abstract Rice has a vital role in food security but the production is limited in infertile and degraded soils. Rice is cultivated on acid sulphate soil in the coastal area of Peninsular Malaysia. Soil amendment using biological charcoal (biochar) increases the soil fertility. Thus, empty fruit bunch biochar (EFBB) was applied in a pot experiment under a controlled environment using an organic system of rice intensification (SRI) practice and its effects on the floodwater pH, acid sulphate soil properties and growth performance of rice and yield of rice MR219 were preliminarily investigated. EFBB increased grain yield by 141 to 472%. Plant growth and yield parameters in EFBB amended soils were significantly higher than in soil without biochar. The number of tillers increased significantly with the increase in biochar applied; 28 tillers were produced in the control, while up to 80 tillers were produced in the plots applied 40 t ha–1 EFBB. Moreover, the decline of Al3+ in flood water indicated that EFBB mitigated Al3+ toxicity. Soil water pH increased from 3.5 to 6 with increasing EFBB application rates. The grain yield was linearly correlated to the application rate of EFBB. This pot study demonstrates that the application of EFBB combined with organic fertilization and intermittent irrigation has the potential to improve rice yield on acid sulphate soil. Further study in the field is warranted to determine the effect of EFBB on large scale rice production.

Changes in phytochemical contents in different parts of Clinacanthus nutans (Burm. f.) lindau due to storage duration

Clinacanthus nutans is a well recognized medicinal herb for its high phytochemical contents. Several aspects may contribute to the phytochemical contents, and thus determine the quality and efficacy of an herb. An experiment was conducted using a completely randomized design (CRD) with five replications, in a factorial arrangement of treatments. including two plant parts harvested at two different stages such as young leaves, young stems, matured leaves and matured stems, and four different storage durations such as 1, 2, 3 and 4 days. The study was aimed at determining how storage duration affects selected phytochemical contents of different plant parts of C. nutans at different harvesting stages. Total phytochemical content, total flavonoids content and DPPH radical scavenging activities are higher in young plants than in old plants, moreover, all those compounds are higher in leaves than in stems, and decrease gradually due to storage. Phytochemical, ascorbic acid and chlorophyll content of C. nutans differ among different plant parts and change due to storage. In general, young plant parts contain higher amount of phytochemicals, ascorbic acid and chlorophyll compared with matured parts confirming that phytochemicals content of C. nutans decreases when plants tend to maturity. Prolonged storage reduces phytochemical, ascorbic acid and chlorophyll content of C. nutans,which demands fresh use of this medicinal herb to avoid phytochemical losses. Further research focusing on the proper storage is necessary to minimize phytochemicals losses of C. nutans.

Comparison of the Microbiological Quality and Safety between Conventional and Organic Vegetables Sold in Malaysia

Given the remarkable increase of public interest in organic food products, it is indeed critical to evaluate the microbiological risk associated with consumption of fresh organic produce. Organic farming practices including the use of animal manures may increase the risk of microbiological contamination as manure can act as a vehicle for transmission of foodborne pathogens. This study aimed to determine and compare the microbiological status between organic and conventional fresh produce at the retail level in Malaysia. A total of 152 organic and conventional vegetables were purchased at retail markets in Malaysia. Samples were analyzed for mesophilic aerobic bacteria, yeasts and molds, and total coliforms using conventional microbiological methods. Combination methods of most probable number-multiplex polymerase chain reaction (MPN-mPCR) were used to detect and quantify foodborne pathogens, including Escherichia coli O157:H7, Shiga toxin-producing E. coli (STEC), Listeria monocytogenes, Salmonella Typhimurium, and Salmonella Enteritidis. Results indicated that most types of organic and conventional vegetables possessed similar microbial count (P > 0.05) of mesophilic aerobic bacteria, yeasts and molds, and total coliforms. E. coli O157:H7 and S. Typhimurium were not detected in any sample analyzed in this study. Among the 152 samples tested, only the conventional lettuce and organic carrot were tested positive for STEC and S. Enteritidis, respectively. L. monocytogenes were more frequently detected in both organic (9.1%) and conventional vegetables (2.7%) as compared to E. coli O157:H7, S. Typhimurium, and S. Enteritidis. Overall, no trend was shown that either organically or conventionally grown vegetables have posed greater microbiological risks. These findings indicated that one particular type of farming practices would not affect the microbiological profiles of fresh produce. Therefore, regardless of farming methods, all vegetables should be subjected to appropriate post-harvest handling practices from farm to fork to ensure the quality and safety of the fresh produce.

Production system and harvesting stage influence on nitrate content and quality of butterhead lettuce

Leafy vegetables such as lettuce grown under different production systems may accumulate different concentrations of nitrate which may reach to the levels potentially toxic to humans. Moreover, nitrate accumulation varies in various plant parts and physiological age of the plant. Therefore, to determine the effect of production system and harvesting stage on nitrate accumulation and quality of butterhead lettuce, a study was conducted considering two lettuce production systems namely hydroponic and organic, and four different harvesting stages such as 35, 38, 41 and 44 days after transplanting (DAT). The experimental design was complete randomized design (CRD) with four replications. Hydroponic and organic systems performed similar in terms of yield, quality and nitrate content of butterhead lettuce. Delaying harvesting can not only increase yield but also can minimize nitrate accumulation and health hazard risk as well. Delay in harvesting stage may result in quality deterioration of lettuce and increased production cost. Thus, a compromise is necessary to consider 41 DAT as the optimum stage to harvest butterhead lettuce with significantly higher reduction of nitrate content in both outer adult leaf blades and young leaves of hydroponic lettuce. Fresh weight, firmness and color of butterhead lettuce at this stage were still acceptable.

Biochar-compost mixture as amendment for improvement of polybag-growing media and oil palm seedlings at main nursery stage

PurposeProduction of oil palm seedling in the nursery mainly utilises top soil as polybag medium. These soils, especially in tropical regions, are acidic and have low organic matter content. The aim of this study was to investigate the effects of oil palm empty fruit bunch (EFB) biochar and compost incorporation as amendment in polybag medium for oil palm seedlings growth at the nursery stage.MethodsA polybag experiment was conducted with four biochar rates (0, 0.5, 1.0 and 1.5% w/w C addition), two compost rates (0 and 30% v/v), and two fertiliser application rates (75 and 100% of recommended rate). The effects of biochar, compost, and biochar-compost combination on oil palm seedling growth was evaluated and the effectiveness of EFB biochar in retaining soil nutrients was determined indirectly by measuring amount of nutrient leached through the polybag medium.ResultsBiochar, compost, and biochar-compost amendment improved polybag media’s chemical properties (pH, total C and N, C:N ratio, CEC, Mg, and Ca). There were no significant effects of the amendments on shoot biomass. However, root growth and shoot:root ratio significantly improved with 1.5% w/w C addition and 30% (v/v) compost with 75% recommended fertiliser rates applied. Furthermore, nutrient leaching measurement indicates that, EFB biochar significantly reduced ammonium-N leaching up to 21–46%.ConclusionsOverall, this study demonstrates the potential of biochar and compost co-application to improve the chemical properties of polybag medium and root development of oil palm seedlings.

Ripening characteristics of vapour heat treated ‘Frangi’ papaya (Carica papaya L. cv. Frangi) as affected by maturity stages and ethylene treatment

‘Frangi’ papaya is a F1 hybrid cultivar produced by Malaysian Agrifood Corporation Bhd in 2006. Since then, ‘Frangi’ papaya is a new hybrid and its physiology may differ from another cultivars. Several importer countries, such as Japan and China, have made the vapour heat treatment (VHT) an export requirement for disinfestation of fruit flies in Malaysia. The exporting country is also required to carry out ripening treatments with ethylene before export. Therefore, the objective of this work was to determine the effects of maturity stages (4, 5 and 6) and ethylene treatments on ripening characteristics of vapour heat treated papaya during storage at 25 °C. Papaya fruits were treated with VHT systems. After VHT, the fruits were exposed with 100 µL.L–1 ethylene gas at 20 °C for 24 h. Non-ethylene treated fruits (control) were kept separately at 20 °C for 24 h. After 24 h, the fruits were removed from the ripening rooms, and stored at 25 °C. The ripening characteristics of fruits that reached maturity stages 4, 5, and 6 were recorded. Results showed that the fruits ripened normally at 25 °C with or without ethylene following VHT with respect to peel and pulp color, edible firmness and soluble solids concentration (SSC). Fruits at maturity stage 5 were considered at the edible stage by taking into account the firmness, SSC, titratable acidity, and ascorbic acid contents. It is recommended that no ethylene treatment is needed to ripen vapour heat treated fruits, since the ethylene treatment did not affect the ripening process of the fruits.