Purwiyatno Hariyadi

Chilling-induced oxidative stress in cucumber fruits

Abstract Oxidative stress was evoked in the peel tissue of cucumber fruits during chilling at 4°C in the dark. Within 2 days of chilling, tissue reduced glutathione (GSH) and thylakoid α-tocopherol (αToc) levels decreased by 28% and 50%, respectively. Tissue ascorbic acid (AA) and thylakoid β-carotene (CAR) levels decreased by 35% and 60%, respectively, between 5 and 7 days of chilling. Rewarming generally had no effect on, or led to further declines in, the levels of these antioxidants. Lipophilic fluorescent products of lipid peroxidation began to accumulate in polar lipid fractions isolated from peel tissue thylakoids after 5–7 days of chilling or chilling/rewarming. This was accompanied by a 2-fold increase in the phospholipid:glycolipid ratio and a slight decrease in the degree of unsaturation of the glycolipids. Measurements of electrolyte leakage of peel tissue indicated that irreversible injury in cucumber fruits required at least 7 days of continuous chilling. None of these changes occurred for fruit held at 13°C in the dark. These results indicate that oxidative stress is an early response of cucumber fruits to chilling and that lipid peroxidation may contribute to the development of chilling injury.

Chilling-induced Oxidative Stress in Cucumber (Cucumis sativus L. cv. Calypso) Seedlings

Summary One-week old cucumber ( Cucumis sativus L. cv. Calypso) seedlings were chilled at 4 °C in the dark for up to 6 days, after which they were rewarmed at 13 °C in the light (16-h photoperiod) for 2 d to allow for recovery. Responses of these seedlings were compared to unchilled controls (13 °C) held in the dark or in the light with a 16-h photoperiod. Loss of viability in dark-chilled seedlings required more than 1 d of chilling and progressed to the point where it was complete after 4 d of chilling. Irreversible increases in cotyledon tissue electrolyte leakage of dark-chilled seedlings did not occur until after seedling collapse, indicating that increases in passive permeability are secondary responses to chilling injury. There were only minor differences in the temporal changes in the tissue antioxidants reduced glutathione, ascorbic acid, atocopherol, and β-carotene between chilled, unchilled, and chilled/rewarmed seedlings, with the exception that slightly lower levels of β-carotene and α-tocopherol may have been induced by dark-chilling. Peroxidation of thylakoid lipids was induced during the rewarming period, after only 1 to 2 d of chilling, as indicated by the accumulation of lipid fluorescent pigments (LFPs). LFPs accumulated in both the phospholipid and glycolipid fractions of thylakoid lipids extracted from rewarmed seedlings, whereas little evidence for lipid peroxidation was obtained for the unchilled controls. Our results indicate that chilling-induced oxidative stress may have a role in transducing chilling injury in cucumber seedlings.

Solvent suitability for lipase-mediated acyl-transfer and esterification reactions in microaqueous milieu is related to substrate and product polarities

Abstract Lipase-mediated esterification and acyl-transfer reactions were evaluated in a series of solvents, ranging in log P (partitioning coefficient of solvent between 1-octanol and water) values from −0.33 to 8.8, and for combinations of substrates of differing polarities. Contrary to the prevailing view, some of the model reaction systems evaluated were most active in solvents having log P values well below the range of 2 to 4 generally believed to be most supportive of biocatalysis in microaqueous organic media. As the polarity of the most polar substrate in the reactive mixtures was progressively increased, there was an attendant decrease in the magnitude and range of solvent log P values yielding maximum activity. When glycerol (log P of −3.0) was used as an acyl-transfer acceptor, log P values of solvents most supportive of activity were −0.33 to 0.80. For acyl-exchange reactions between triacetin (log P of −0.075) and olive oil, solvents having log P of 0.60 to 1.9 were most supportive of activity. For esterification reactions involving benzyl alcohol (log P of 1.1) or dodecanoic acid (log P of 4.8) as the most polar substrate, solvents of log P values > 2.5 and 3.5, respectively, were most supportive of raction. Although there are likely some specific solvent effects, we conclude that the choice of solvent to serve as bulk phase for biocatalytic processes should be made in cognizance of the relative polarity of substrates (and products) of the designed reaction. A secondary feature that should also be considered is the macroscopic phase behavior of reactive mixtures, although this parameter appears to be dependent on the particular source of enzyme.

Technical aspects of food fortification

The nutritional status of the population is one of the important factors determining the quality and productivity of the population, which in turn affects national productivity. in the long term, good nutritional status contributes to the intelligence and health of the population. Consequently, programmes directed at improving the nutritional status of the population will undoubtedly be a high priority in the national development scheme of any country, developed or developing. Food fortification, i.e., the addition of nutrients to specific foods based on the dietary habits and nutritional status of the target population, is one of the most popular nutritional interventions for improving the populations nutritional status. for food-fortification programmes to be successful, their technical aspects need to be carefully assessed. These include the nutritional justification for food fortification, the acceptability of the fortified food product to consumers (both cost and taste), and any technical or analytical limitation to compliance with food regulations and labeling requirements. Important technical aspects of developing effective food-fortification programmes are the choice of food carrier, nutrient interactions, bioavailability of nutrients, stability of nutrients added under anticipated conditions of storage and processing (food preparation at the household level), and safety. A good fortified product should not cause nutrition imbalance, and excessive intake of nutrients should not have adverse effects. to provide better information for the consumer, the concept of overage should be introduced. Overage is the use of kinetic data on nutrient stability to calculate the amount of added nutrient so that the anticipated level of the nutrient at the end of the products shelf life is in accordance with the level indicated on the label.

Biochemical characteristics of chitosanase from the Indonesian Bacillus licheniformis MB-2

Bacillus licheniformis MB-2, isolated from a hot spring water in Manado, Indonesia, secreted a unique chitosanase. Media consisted of 0.24% chitosan, 0.25% casiton, 1% MgSO4, 1.4% K2HPO4, 0.02% CaCl2·2H2O, 0.002% FeSO4·7H2O (w/v) was used for enzyme production. Purification of the enzyme through the hydrophobic interaction chromatography system (butyl Sepharose 4 FF) resulted in two major active fractions; the F2 fraction was shown as a single band at both sodium dodecyl sulfate-polyacrylamide gel electrophoresis and zymogram analysis with apparent molecular mass of 75 kDa. The enzyme worked best at 70°C and pH between 6.0 and 7.0. When incubated at 70, 80, and 90°C, the t1/2 values were 26.56, 18.44, and 16.74 min, respectively with the k constant being at 0.026, 0.037, and 0.04/min. When heated at 90°C, the enzyme retained its activity up to 8 h in the presence of 1mM MnCl2. The enzymes activity was unaffected by the presence of 1 M NaCl and 6 M urea but was decreased by 2 M of guanidine hydrochloride. Albeit the enzyme did not degrade colloidal and glycol chitin, it hydrolyzed glycol chitosan up to 0.8% and colloidal chitosan up to 11%. The 85% deacetylated (DDA) soluble chitosan was the most susceptible to this enzyme, followed by 90% and 100% DDA chitosan. The Km app values of the 85, 90, and 100% DDA soluble chitosans were found as 0.23, 0.24, and 0.58 mg/mL, whereas the Vmax values were 843, 668, and 261 U/mg, respectively. The hydrolysis products of F2 chitosanase at 24 h incubation (70°C) were pentasaccharide (GlcN)5 and hexasaccharide (GlcN)6. The prelimiaary test showed inhibitory effect of chitooligosaccharides resulted from enzymatic degradation toward Pseudomonas aeruginosa, Salmonella typhimurium. Listeria monocytogenes, Bacillus cereus, Escherichia coli, and Staphylococcus aureus.

Sensory and Peptides Characteristics of Soy Sauce Fractions Obtained by Ultrafiltration

Soy sauce is a light brown to black liquid having umami and delicious tastes with an appetizing aroma. The most known type of soy sauce is the salty soy sauce. This soy sauce can be grouped into two types, i.e., a Japanese type (only found in Japan) and a Chinese type (produced in China and South East Asia). The Japanese soy sauce uses soybean and wheat (ratio 1:1) as the main raw material, whereas the Chinese type uses no or very little wheat besides soybean (Roling, 1995). In Indonesia, traditional soy sauce producers usually use black soybean, but some use yellow soybean, whereas modern producer use a mixture of wheat and defatted soybean. The main preparation of this soy sauce involves mold and brine fermentation to afford moromi which is then filtered and pasteurized to give soy sauce.

Mobilization of primary metabolites and phenolics during natural fermentation in seeds of Pangium edule Reinw.

Abstract Fermented seeds of the tropical tree Pangium edule Reinw. are a speciality in Indonesia and have been used as spices. The fermentation process of the seeds is a natural spontaneous process, which occurs 40 days following seed maturity and treatment. This study reports some biochemical changes, especially primary metabolites, and antioxidant activity associated with mobilization of lipids and phenolics during seed fermentation. The lipid content increased slightly (46.07–50.95% db) although the dominant fatty acid composition did not change. The dominant fatty acids were oleic acid (C 18:1 n-9) and linoleic acid (C 18:2 n-6). During fermentation, the decrease in fatty acid content in lipid coincided with the increasing acid value, which indicated that free fatty acids increased in seeds during fermentation. The dominant tocol in the seed, γ-tocotrienol, increased (69.8–123.3 μg g −1 freeze-dried seed) during fermentation. In general, overall protein content and amino acid composition did not change but non-soluble protein increased while soluble protein decreased. The changes in carbohydrate fraction showed that total crude carbobydrate, neutral detergent fibre (NDF, as cellulose, hemicellulose, and lignin) decreased, but reducing sugar increased and starch content did not change. Enzyme assays showed that microorganisms may be involved in the fermentation process. β-glucosidase, an enzyme that can cleave glycosidic bonds of conjugated phenolics and guaiacol peroxidase (GPX) activities increased. The total phenolics content in seeds increased substantially corresponding to the increase in β-glucosidase but antioxidant activity of phenolic extracts did not change.

Quality of Vegetable Oil Prior to Fortification Is an Important Criteria to Achieve a Health Impact

Unbranded palm cooking oil has been fortified for several years and can be found in the market with different oxidation levels. This study aimed to investigate the stability and shelf life of unbranded, bulk, vitamin A-fortified palm oils with the most commonly observed oxidation levels in Indonesia. Three types of cooking oils were tested: (i) cooking oil with a peroxide value (PV) below 2 mEq O2/kg (PO1); (ii) cooking oil with a PV around 4 mEq O2/kg (PO2); and (iii) cooking oil with a PV around 9 mEq O2/kg (PO3). The oil shelf life was determined by using accelerated shelf life testing (ASLT), where the product was stored at 60, 75 and 90 °C, and then PV, free fatty acid and vitamin A concentration in the oil samples were measured. The results showed that PO1 had a shelf life of between 2–3 months, while PO2’s shelf life was a few weeks and PO3’s only a few days. Even given those varying shelf lives, the vitamin A loss in the oils was still acceptable, at around 10%. However, the short shelf life of highly oxidized cooking oil, such as PO3, might negatively impact health, due to the potential increase of free radicals of the lipid peroxidation in the oil. Based on the results, the Indonesian government should prohibit the sale of highly-oxidized cooking oil. In addition, government authorities should promote and endorse the fortification of only cooking oil with low peroxide levels to ensure that fortification is not associated with any health issues associated with high oxidation levels of the cooking oil.

Effect of tocopherols, tocotrienols, β-carotene, and chlorophyll on the photo-oxidative stability of red palm oil

Effect of tocols, β-carotene, and chlorophyll on photo-oxidative stability of red palm oil (RPO) were studied. Model systems of triacylglycerols+tocols, triacylglycerols+β-carotene, triacylglycerols +tocols+β-carotene, and triacylglycerols+tocols+β-carotene+chlorophyll were exposed to fluorescent light at intensities of 5,000, 10,000, and 15,000 lux for 7 h at 30±2°C. Changes in concentrations of tocopherols, tocotrienols, β-carotene, chlorophyll, and peroxide values were evaluated every hour. Light intensity accelerated degradation of tocols in the triacylglycerols+tocols system and β-carotene in the triacylglycerols+β-carotene system. Gamma-tocotrienol showed the highest degradation rate and β-carotene was the most sensitive compound to changes in light intensity, indicated by the lowest light intensity coefficient (zi) value. The presence of tocols and β-carotene together showed protective effects for the photo-oxidative stability of RPO. The presence of chlorophyll increased the rate of photo-oxidation at high light intensities. Interactions between tocols and β-carotene contributed to the photo-oxidative stability of RPO.

The colour degradation of anthocyanin-rich extract from butterfly pea (Clitoria ternatea L.) petal in various solvents at pH 7

Abstract A spectroscopic study was conducted to evaluate the colour degradation mechanism of anthocyanin-rich extract from butterfly pea petal. The extract was diluted in four different solvent systems, which were buffer solution pH 7 (AQ7) and the mixture of organic solvent with buffer solution pH 7 (4:1 v/v). The organic cosolvent involved were methanol (ME7), ethanol (ET7) and acetone (AC7). The samples were stored in containers with 0% and 50% headspace, and their colour intensity, total anthocyanin and hypsochromic shift were evaluated periodically. The rank of colour and anthocyanin degradation from the biggest was AQ7 > ME7 > ET7 > AC7. The longest hypsochromic shift was AQ7 > ME7 > ET7, while in AC7 the shift was absent. There was evidence that the volume of package headspace provoked colour stability. The colour degradation in AC7 was proposed to occur through hydrophobic interaction unfolding, and in AQ7 was through the deacylation, while in ME7 and ET7 was due to both mechanisms.