Salmah Yusof

Antioxidative activity and total phenolic compounds of leaf, root and petiole of four accessions of Centella asiatica (L.) Urban

Antioxidative activity and total phenolic compounds of root, leaf and petiole of four accessions of Centella asiatica (L.) Urban, namely CA 01, CA 05, CA 08 and CA 11, were evaluated. Antioxidative activity of the extracts was measured using the ferric thiocyanate (FTC) method and thiobarbituric acid (TBA) test. The antioxidative activities were then compared with that of a-tocopherol (natural antioxidant) and butylated hydroxytoulene or BHT (synthetic antioxidant). The results showed that CA 01 and CA 05 had the highest antioxidative activities among the accessions tested. Results also showed that both leaf and root of C. asiatica had high antioxidative activity, which was as good as that of a-tocopherol. The total phenolic content, determined according to the Folin–Ciocalteu method, varied from 3.23 to 11.7 g/100 g dry sample, and showed strong association (r 2 =0.90) with antioxidative activity. The results suggest that phenolic compounds are the major contributors to the antioxidative activities of C. asiatica. # 2003 Elsevier Science Ltd. All rights reserved.

Physico‐chemical characteristics of roselle (Hibiscus sabdariffa L.)

The physico‐chemical characteristics of roselle from Malaysia were studied. The parameters analysed included size, weight, pH, titratable acidity, soluble solids, anthocyanin contents, organic acids and sugars. Succinic and oxalic acids were the predominant organic acids found in roselle while glucose was the major sugar present. The present study was also conducted to determine and quantify the most biologically effective natural antioxidants present in roselle. Ascorbic acid, β‐carotene and lycopene, were separated, identified and quantified by HPLC. The amounts of ascorbic acid, β‐carotene and lycopene contents were 141.09mg/100g, 1.88mg/100g and 164.34μg/100g, respectively. The individual anthocyanin in roselle was characterised by TLC and HPLC. Delphinidin‐3‐sambubioside and cyanidin‐3‐sambubioside were the main anthocyanin present in roselle.

Naringin content in local citrus fruits.

Abstract The content of bitter component (naringin) from the skin, juice and seed of musk lime, mexican lime, rough lime, pummelo and mandarin orange was determined by the high-performance liquid chromatographic (HPLC) method. Naringin could only be found in pummelo and rough lime but could not be detected in musk lime, mexican lime and mandarin orange. The skin of pummelo contained a higher amount of naringin (3910 μg/g fresh weight) than the juice (220·0 μg/g fresh weight) whereas the amounts of naringin obtained from the skin, juice and seed of rough lime were 517·2 μg/g, 98·4 μg/g and 29·2 μg/g fresh weight, respectively. Sensory analysis further confirmed that the juices extracted from pummelo and rough lime were bitter while those extracted from musk lime, mexican lime and mandarin orange were not bitter. The correlation coefficient (r) for bitterness using both techniques (sensory and HPLC) was 0·97.

Changes in quality of sugar-cane juice upon delayed extraction and storage.

Abstract The quality of sugar-cane juice extracted from stored canes, as well as changes in quality of fresh juice stored at different temperatures, were studied. Cane stems were stored at 10±1°C, 85–88% relative humidity (RH) and 27±1°C, 55–85% RH, while fresh juice was stored at 5±1°C, 61–84% RH and 27±1°C, 55–85% RH. The physicochemical parameters evaluated were juice yield, juice colour, total soluble solids, sugar content (sucrose, fructose, glucose), titratable acidity, pH, chlorophyll content and sensory evaluation for colour and flavour. Viscosity and total microbial count on stored cane juice were also determined. Results showed that low temperature storage (10°C) of canes was able to maintain the quality of juice for up to 9 days while low temperature storage (5°C) of juice could last for only 4 days. During storage, sucrose contents decreased while fructose, glucose and titratable acidity increased in both types of samples. The colour changes in juice extracted from stored canes was inconspicuous until day 9. Deterioration of cane stored at 27±1°C occurred faster than that stored at 10±1°C. Fresh sugar-cane juice became spoiled after 4 days when stored at 5±1°C and 1 day when stored at 27±1°C. Microbial count, especially lactic acid bacteria count, increased during storage of cane juice.

Quality of soursop juice after pectinase enzyme treatment

Abstract A pectinase enzyme was used at 0-0.1% concentrations to help in the extraction of soursop juice. The incubation times were from 1–3 h. The juices obtained were evaluated for yield, titratable acidity, pH, ascorbic acid, total soluble solids, viscosity, turbidity and sugar contents. Results indicated that the use of enzyme was beneficial as it increased the yield of juice by 41%. There were significant increases in acidity and Brix and significant decreases in viscosity and turbidity. There were no significant changes in the ascorbic acid and sugar contents. Sensory evaluation results indicate that the extracted juice was superior in quality to a commercial product.

Antioxidative properties of roselle (Hibiscus sabdariffa L.) in linoleic acid model system

A study was conducted to determine the antioxidative properties of roselle (Hibiscus sabdariffa L.) methanol extract by monitoring the formation of diene‐conjugated compounds and thiobarbituric acid reactive substances (TBARS) in linoleic acid model system. The properties were compared to those of butylated hydroxy‐anisole (BHA) and α‐tocopherol. Results indicated that the roselle extract showed stronger antioxidant properties than BHA or α‐tocopherol. A total of 200 parts per million (ppm) of the extract inhibited more than 85 per cent of diene‐conjugated compounds after seven days of incubation at 40○C. The total phenolic compound was found to be 2.96mg/g calyx as gallic acid equivalent. This indicates that roselle is a good source of natural antioxidants which may protect the body from damage by free radicals and lipid peroxidation. The protective effect is probably through the action of highly bioavailable ascorbic acid, β‐carotene and phenolic compounds, especially the anthocyanins.

Effects of type of packaging materials on physicochemical, microbiological and sensory characteristics of durian fruit leather during storage

A study on storage stability of durian leather was carried out at room temperature using four types of packaging materials - laminated aluminium foil (LAF), high-density polyethylene (HDPE), low-density polyethylene (LDPE) and polypropylene (PP) films - for 12 weeks. Analyses on physicochemical, microbiological and sensory characteristics were conducted at weeks 0, 2, 4, 8 and 12. Analyses for sugar, fat and caloric contents were conducted at the beginning and the end of storage period. Moisture contents and water activity (A(w)) fluctuated during storage but tended to decrease after week 8. Non-enzymatic browning increased significantly (P < 0.05) for all samples in packaging materials used; the highest increases were observed in LDPE-packed leather. The increases were related to the changes in colour of samples during storage. The longer storage time, the higher L and b values and the lower a value. The pH, although it fluctuated in the first weeks, slightly increased at the end of the storage period, while the hardness for each sample gradually increased during the storage. Microbial analyses showed that total mesophilic bacteria (TMB) and total moulds and yeast (TMY) counts were low, where after 12-week storage TMB and TMY were less than 60 and 140 cfu g-1, respectively. Organoleptically, for all attributes evaluated, all samples were acceptable by panelists during the 12-week storage period.

Physico-chemical changes in sugarcane (Saccharum officinarum var yellow cane) and the extracted juice at different portions of the stem during development and maturation

A study was conducted to determine the physicochemical differences between portions (top, middle, and bottom) of sugarcane at different maturation stages (between 3 and 10 months from planting). The variety used was Saccharum officinarum var. Yellow cane. The parameters analysed were weight, diameter, yield, total soluble solids (TSS), pH, titratable acidity, sugar content (sucrose, glucose, fructose). The weight, diameter, total soluble solids (TSS) and sucrose content increased significantly (P<0.01) in all portions (top, middle and bottom) up to the end of maturity. On the other hand, titratable acidity (TA), pH, juice yield, glucose and fructose contents decreased significantly (P<0.01) during maturation. However, significant differences were also detected in weight, diameter, TSS, sugar content, pH, TA and juice yield between the different portions during maturation. Sucrose content, juice yield and TSS were found to be the most suitable indicators of maturity, while TA, glucose and fructose contents were found to be poor maturity indicators. A suitable harvesting stage was found to be between 7 and 8 months after planting. Copyright

Effect of roselle (Hibiscus sabdariffa L.) on serum lipids of Sprague Dawley rats

The efficacy of roselle as a functional food has been revealed lately, especially for its antioxidant bioactivity. In this study, the benefits of roselle were further studied in vivo using the model of male Sprague Dawley rats fed with normal diets (C), 2.5 percent roselle (R), 2.5 percent roselle with 15 percent soybean oil (RO) and 15 percent soybean oil (O) for 25 weeks. The results demonstrated that supplementation of roselle in the diets significantly (p < 0.05) reduced the gross body weight and increased the high‐density lipoproteins cholesterol (HDL‐C) compared to the rats fed with normal diets and oil diets, and reduced the level of triglycerides in the serum. Serum total cholesterol of R group decreased compared to C but increased in RO compared to O group. Significant increase (p < 0.05) of serum uric acid was observed in R group at week 15 and 20. Addition of roselle in oil diet significantly decreased (p < 0.05) the malondialdehyde formation at week 20 and 25 but there was no significant effec...

Performance of a lipase-catalyzed transesterified palm kernel olein and palm stearin blend in frying banana chips

Abstract The frying performance of an enzymatically transesterified palm stearin and palm kernel olein (1:1 by weight) blend was compared with its control (physical mixture or no enzyme added) and a commercial plastic frying shortening (CS). The samples were used as deep-fat frying media at 180°C for banana chips for seven consecutive days. The samples were then analysed for iodine value (IV), free fatty acid (FFA) content, peroxide value (PV), thiobarbituric acid (TBA) value, p-anisidine value (AV), total polar compounds (TPC), fatty acid composition, specific extinction, E1%1cm at 233 and 269 nm, polymer contents, viscosity and colour indices. The fried banana chips were analysed for acceptability by sensory evaluations. Storage properties of the banana chips were also evaluated by trained sensory panellists and a modified TBA test. The transesterified blend was found to have significantly (P 0.05; for all the attributes tested) between the acceptability of the banana chips fried by the transesterified and control blends. However, the banana chips fried in CS had significantly (P