Nyuk Ling Chin

Simplex-centroid mixture formulation for optimised composting of kitchen waste

Composting is a good recycling method to fully utilise all the organic wastes present in kitchen waste due to its high nutritious matter within the waste. In this present study, the optimised mixture proportions of kitchen waste containing vegetable scraps (V), fish processing waste (F) and newspaper (N) or onion peels (O) were determined by applying the simplex-centroid mixture design method to achieve the desired initial moisture content and carbon-to-nitrogen (CN) ratio for effective composting process. The best mixture was at 48.5% V, 17.7% F and 33.7% N for blends with newspaper while for blends with onion peels, the mixture proportion was 44.0% V, 19.7% F and 36.2% O. The predicted responses from these mixture proportions fall in the acceptable limits of moisture content of 50% to 65% and CN ratio of 20-40 and were also validated experimentally.

Textural, Rheological and Sensory Properties and Oxidative Stability of Nut Spreads—A Review

Tree nuts are rich in macro and micronutrients, phytochemicals, tocopherols and phenolic compounds. The development of nut spreads would potentially increase the food uses of nuts and introduce consumers with a healthier, non-animal breakfast snack food. Nut spreads are spreadable products made from nuts that are ground into paste. Roasting and milling (particle size reduction) are two important stages for the production of nut spreads that affected the textural, rheological characteristic and overall quality of the nut spread. Textural, color, and flavor properties of nut spreads play a major role in consumer appeal, buying decisions and eventual consumption. Stability of nut spreads is influenced by its particle size. Proper combination of ingredients (nut paste, sweetener, vegetable oil and protein sources) is also required to ensure a stable nut spread product is produced. Most of the nut spreads behaved like a non-Newtonian pseudo-plastic fluid under yield stress which help the producers how to start pumping and stirring of the nut spreads. Similar to other high oil content products, nut spreads are susceptible to autoxidation. Their oxidation can be controlled by application of antioxidants, using processing techniques that minimize tocopherol and other natural antioxidant losses.

Extraction of Total Phenolic Content from Garcinia mangostana Linn. hull. I. Effects of Solvents and UV–Vis Spectrophotometer Absorbance Method

The effect of solvents with different polarity on the extraction of total phenolic content from mangosteen hull was investigated. The Folin–Ciocalteu (FC) method, expressed in equivalent to gallic acid concentration was used to quantify total phenolic content. Methanol was the most effective solvent in giving the highest recovery (p < 0.05) of phenolic compounds, compared to ethanol, acetone, isopropanol, ethyl acetate and distilled water. Regression analysis was performed to evaluate the relationship between the direct absorbance method and the FC method for total phenolic contents determination. Strong coefficients of determinations (R2 ≥ 0.990) were obtained for the absorbance of acetone, ethanol, and methanol extracts suggesting the regression equations obtained can be used to determine the total phenolic contents without using the FC method.

Effects of Temperatures on Rheological Behavior of Dragon Fruit (Hylocereus sp.) Juice

In Malaysia, the dragon fruit is widely commercialized. It is extensively used in the food industry. Their use as constituents of juices, jellies, marmalades, jams, wine, beverages, etc. generates a consumer market with an increasing demand. This work aims to obtain rheological data of dragon fruit juice which is essential in optimizing equipment design, process control, and consumer acceptability of a product. In the present study, dragon fruit juice with concentrates of (10 and 12oBrix) was prepared. The rheological behavior of these concentrates was studied in the temperature range of 5, 10, 15, and 40oC. Dragon fruit juice was found to exhibit non-Newtonian, pseudoplastic behavior. Samples on both concentrations were adequately described by the rheological model. The effect of temperature on dragon fruit juice is best described by the applicability of the Arrhenius model related to apparent viscosity, ?a.

Development of Pistachio (Pistacia vera L.) spread.

UNLABELLED Pistachio nut (Pistacia vera L.) is one of the most delicious and nutritious nuts in the world. Pistachio spreads were developed using pistachio paste as the main component, icing sugar, soy protein isolate (SPI), and red palm oil (RPO), at different ratios. The highest mean scores of all the sensory attributes were depicted by spreads that were made without addition of SPI. It was found that the work of shear was 0 to 11.0 kg s for an acceptable spread. Sensory spreadability, overall texture, spreadability, and overall acceptability were negatively correlated (R > 0.83) with the work of shear of spreads. The findings indicated that the presence of RPO had a direct effect on the viscoelastic behavior of the pistachio spreads. The a values, which are related to the green color of the pistachio product ranged from 1.7 to 3.9 for spread without addition of RPO, and 4.0 to 5.3 in the presence of RPO. PRACTICAL APPLICATION The development of pistachio spread would potentially increase the food uses of pistachio and introduce consumers with a healthier snack food.

Effects of bulking agents, load size or starter cultures in kitchen-waste composting

BackgroundTo prevent the interruption of the carbon cycle by the disposal of waste to landfills, organic kitchen waste requires proper treatment such as composting to reduce its uncontrolled degradation on disposal sites and subsequent greenhouse gases, odour emissions and nutrient losses. This study investigated the effects of bulking agent, newspaper and onion peels, composting waste load sizes of 2 and 6 kg, or the use of starter culture on kitchen-waste composting consisting of nitrogen-riched substrates, vegetable scraps and fish processing waste in an in-vessel system. The optimised formulation of kitchen waste mixture was used for a 30-day composting study, where the temperature profiles were recorded and the carbon-to-nitrogen ratios were measured as an indication of compost maturity. The kitchen-waste composting process was conducted in parallel in two fabricated kitchen waste composters.ResultsIt was found that the onion peels were more suitable in producing matured compost where the carbon-to-nitrogen ratio reduced to 10 within 16 days of composting. A smaller kitchen waste load size of 2 kg gave a shorter composting time by half when compared to the 6 kg. The use of a microbial cocktail consisting seven types of bacteria and eight types of fungi isolated from soils as a starter culture for this kitchen-waste composting did not show advantages in accelerating the composting process.ConclusionsThe results suggest that the in-vessel kitchen-waste composting can be efficient with a minimal load of about 2 kg using onion peels without additional starter culture.

Functional Effect of Fully Hydrogenated Palm Oil-based Emulsifiers on Baking Performance of White Bread

Breadmaking experiments were undertaken to investigate the effect of addition of selected fully hydrogenated palm oil-based emulsifiers (DATEM, SSL and DMG) on the baking performance of open top white breads in terms of volume, oven spring, weight, density, color, crumb texture and shelf life using the strong and weak flours. The bread samples were prepared using straight dough method with standardized formulation for every experiment except varying six usage levels of emulsifier from 0.0% (control sample) up to 1.25% based on flour weight. The properties of bread were objectively measured and quantitatively analyzed using analysis of variance (ANOVA) with 5% significance level. Emulsifier performed most effectively at a usage level of 0.50% of flour weight. DATEM was effective as volume and oven spring improver while SSL was effective in improving crumb texture. As overall, emulsifier added breads had larger volume, higher oven spring, lower weight and density, whiter color, finer crumb texture and longer shelf life compared to control breads. The improvement in baking performance with added emulsifier was more prominent for the strong flour compared to weak flour.

Rheological Properties of Diluted Pummelo Juice as Affected by Three Different Concentrations

Pummelo is a popular fruit that has great potential to be commercialized. The physico-chemical characterization of pummelo juice such as proximate analysis, pH, moisture content, protein, fat, carbohydrate, ash and fibre contents are investigated. The rheological characterization of pummelo juice was modeled by several models, such as Bingham, Power Law and Casson models. Regression analysis shows good agreements for all three models applied in this study. Pummelo juice exhibits pseudoplastic behaviour under the conditions tested, as indicated by flow behaviour indices (n) ranging from 0.1 to 0.9 from power law model, indicating strong shear-thinning behaviour.

Effect of acetone extract from stem bark of Acacia species (A. dealbata, A. ferruginea and A. leucophloea) on antioxidant enzymes status in hydrogen peroxide-induced HepG2 cells

Acacia species are multipurpose trees, widely used in the traditional systems of medicine to treat various ailments. The major objective of the present study was to determine the gene expression of enzymatic antioxidants by acetone extract from the stem bark of three Acacia species (Acacia dealbata, Acacia ferruginea and Acacia leucophloea) in hydrogen peroxide (H2O2)-induced human hepatoma (HepG2) cells. The expression of antioxidant enzymes such as superoxide dismutase containing copper–zinc (CuZnSOD)/manganese (MnSOD), catalase (CAT) and glutathione peroxidase (GPx) in HepG2 cells was evaluated by real-time PCR. The results of antioxidant enzyme expression in real-time PCR study revealed that the H2O2 (200 μM) challenged HepG2 cells reduced the expression of enzymes such as SOD, GPx and CAT. However, the cells pre-treated with acetone extracts of all the three Acacia species significantly (P > 0.05) up-regulated the expression of antioxidant enzymes in a concentration dependent manner (25, 50 and 75 μg/mL). In conclusion, the findings of our study demonstrated that the acetone extract of Acacia species effectively inhibited H2O2 mediated oxidative stress and may be useful as a therapeutic agent in preventing oxidative stress mediated diseases.

Classification of entomological origin of honey based on its physicochemical and antioxidant properties

ABSTRACT Physicochemical and antioxidant properties of raw honeys from Malaysia were used as markers for determining its entomological source of bee species of Apis dorsata, Apis mellifera, Apis cerana, or Heterotrigona itama. Physicochemical properties of moisture content, water activity, specific gravity, viscosity, pH, free acidity, electrical conductivity, colour (L*, a* and b*), colour intensity, and antioxidant properties including the DPPH free radical scavenging activity power (1/IC50), ascorbic acid equivalent antioxidant content (AEAC), ferric ion reducing antioxidant power (FRAP), and total phenolic content (TPC) were measured and analysed. Honeys were classified into two major groups of those from honey bees (Apis spp.) and Trigona stingless bees (Heterotrigona itama) from its physicochemical and antioxidant properties using hierarchical cluster and principal component analyses. The Kelulut honey produced by stingless bees, Heterotrigona itama was differentiable from honeys from the regular honey bee species, the Apis spp. with characteristics of high moisture content of 33.24 g/100 g, free acidity of 136.8 meq/kg, colour intensity of 990.3 mAU, AEAC of 26.64 mg/100 g, and FRAP of 41.95 mg AAE/100 g. Honey classification by its entomological origin helps in honey identification and it reduces honey fraudulence.