This study demonstrates the potential of Na-silica waste sponge as a source of low cost catalyst in the transesterification of waste cooking oil aided by ultrasound. In this work an environmentally friendly and efficient transesterification process using Na-loaded SiO2 from waste sponge skeletons as a solid catalyst is presented. The results showed that the methyl esters content of 98.4±0.4wt.% was obtainable in less than an hour (h) of reaction time at 55°C. Optimization of reaction parameters revealed that MeOH:oil, 9:1; catalyst, 3wt.% and reaction duration of 30min as optimum reaction conditions. The catalyst is able to tolerant free fatty acid and moisture content up to 6% and 8%, respectively. In addition, the catalyst can be reused for seven cycles while maintaining the methyl esters content at 86.3%. Ultrasound undoubtedly assisted in achieving this remarkable result in less than 1h reaction time. For the kinetics study at 50-60°C, a pseudo first order model was proposed, and the activation energy of the reaction is determined as 33.45kJ/mol using Arrhenius equation.
This study aimed to investigate the changes in the proteome of bitter gourd prior to and after subjecting to boiling and microwaving. A comparative analysis of the proteome profiles of raw and thermally treated bitter gourds was performed using 2D-DIGE. The protein content and number of protein spots in raw sample was higher when compared to the cooked samples. Qualitative analysis revealed that 103 (boiled sample) and 110 (microwaved sample) protein spots were up regulated whereas 120 (boiled sample) and 107 (microwaved sample) protein spots were down regulated. Ten protein spots with the highest significant fold change in the cooked samples were involved in carbohydrate/energy metabolisms and stress responses. Small heat shock proteins, superoxide dismutase, quinone oxidoreductase, UDP-glucose pyrophosphorylase and phosphoglycerate kinase play a role in heat-stress-mediated protection of bitter gourd. This study suggests that appropriate heat treatment (cooking methods) can lead to induction of selected proteins in bitter gourd.
The objective of this study was to evaluate the precursors of acrylamide formation in sweet potato (SP) (Ipomoea batatas L. Lam) chips and to determine the effect of different types of vegetable oils (VOs), that is, palm olein, coconut oil, canola oil, and soya bean oil, on acrylamide formation. The reducing sugars and amino acids in the SP slices were analyzed, and the acrylamide concentrations of SP chips were measured. SP chips that were fried in a lower degree of unsaturation oils contained a lower acrylamide concentration (1443 μg/kg), whereas those fried with higher degree of unsaturated oils contained a higher acrylamide concentration (2019 μg/kg). SP roots were found to contain acrylamide precursors, that is, 4.17 mg/g glucose and 5.05 mg/g fructose, and 1.63 mg/g free asparagine. The type of VO and condition used for frying, significantly influenced acrylamide formation. This study clearly indicates that the contribution of lipids in the formation of acrylamide should not be neglected.
A number of offensive odorants including volatile organic compounds (VOCs), reduced sulfur compounds (RSCs), carbonyls, and ammonia were measured along with several reference pollutants (like benzene (B), CS(2), SO(2), CO, and total hydrocarbon (THC)) from combusted fumes of barbecue charcoals produced from five different countries (Korea, China, Indonesia, Malaysia, and the US). Although the emission concentrations of most odorants were generally below the reference guideline set by the malodor prevention law in Korea, the mean concentration of some aldehydes (acetaldehyde, propionaldehyde, and isovaleraldehyde) and ammonia exceeded those guidelines. As such, aldehydes were the most dominant odorant released from charcoal combustion followed by VOC and ammonia. If odorant levels of charcoal products are compared, there are great distinctions between the products of different countries. If comparison is made using the concept of the sum of odor intensity (SOI), the magnitude of SOI for the charcoal products from the five different countries varied in the order of 4.30 (Korea), 3.10 (Indonesia), 2.97 (China), 2.76 (Malaysia), and 2.76 (the US).
The catalytic cracking of waste cooking palm oil to biofuel was studied over different types of nano-crystalline zeolite catalysts in a fixed bed reactor. The effect of reaction temperature (400-500 °C), catalyst-to-oil ratio (6-14) and catalyst pore size of different nanocrystalline zeolites (0.54-0.80 nm) were studied over the conversion of waste cooking palm oil, yields of Organic Liquid Product (OLP) and gasoline fraction in the OLP following central composite design (CCD). The response surface methodology was used to determine the optimum value of the operating variables for maximum conversion as well as maximum yield of OLP and gasoline fraction, respectively. The optimum reaction temperature of 458 °C with oil/catalyst ratio=6 over the nanocrystalline zeolite Y with pore size of 0.67 nm gave 86.4 wt% oil conversion, 46.5 wt% OLP yield and 33.5 wt% gasoline fraction yield, respectively. The experimental results were in agreement with the simulated values within an experimental error of less than 5%.
Migration of melamine has been determined for 41 types of retail melamine-ware products in Malaysia. This study was initiated by the Ministry of Health, Malaysia, in the midst of public anxiety on the possibility of melamine leaching into foods that come into contact with the melamine-ware. Thus, the objective of this study was to investigate the level of melamine migration in melamine utensils available on the market. Samples of melamine tableware, including cups and plates, forks and spoons, tumblers, bowls, etc., were collected from various retail outlets. Following the test guidelines for melamine migration set by the European Committee for Standardisation (CEN 2004) with some modifications, the samples were exposed to two types of food simulants (3% acetic acid and distilled water) at three test conditions (25°C (room temperature), 70 and 100°C) for 30 min. Melamine analysis was carried out using LC-MS/MS with a HILIC column and mobile phase consisting of ammonium acetate/formic acid (0.05%) in water and ammonium acetate/formic acid (0.05%) in acetonitrile (95 : 5, v/v). The limit of quantification (LOQ) was 5 ng/ml. Melamine migration was detected from all samples. For the articles tested with distilled water, melamine migration were [median (interquartile range)] 22.2 (32.6), 49.3 (50.9), 84.9 (89.9) ng/ml at room temperature (25°C), 70 and 100°C, respectively. In 3% acetic acid, melamine migration was 31.5 (35.7), 81.5 (76.2), 122.0 (126.7) ng/ml at room temperature (25°C), 70 and 100°C, respectively. This study suggests that excessive heat and acidity may directly affect melamine migration from melamine-ware products. However the results showed that melamine migration in the tested items were well below the specific migration limit (SML) of 30 mg/kg (30,000 ng/ml) set out in European Commission Directive 2002/72/EC.
Yellow alkaline noodles (YAN) prepared by partial substitution of wheat flour with soy protein isolate and treated with microbial transglutaminase (MTG) and ribose were investigated during cooking. Cooking caused an increase in lightness but a decrease in redness and yellowness, pH, tensile strength and elasticity values of noodles. The extents of these changes were influenced by formulation and cross-linking treatments. The pH and lightness for YAN-ribose were lowest but the yellowness and redness were the highest whilst the tensile strength and elasticity values remained moderate. For YAN-MTG, the color and pH values were moderate, but tensile strength and elasticity values were the highest. YAN prepared with both cross-linking agents had physical values between YAN-ribose and YAN-MTG. Although certain sensory parameters showed differences in score, the overall acceptability of all 10-min-cooked YAN was similar. It is possible to employ cross-linking agents to improve physical properties of cooked YAN.
In this work, the esterification of free fatty acids (FFA) in waste cooking oil catalysed by ferric sulphate was studied as a pre-treatment step for biodiesel production. The effects of reaction time, methanol to oil ratio, catalyst concentration and temperature on the conversion of FFA were investigated on a laboratory scale. The results showed that the conversion of FFA reached equilibrium after an hour, and was positively dependent on the methanol to oil molar ratio and temperature. An optimum catalyst concentration of 2 wt.% gave maximum FFA conversion of 59.2%. For catalyst loadings of 2 wt.% and below, this catalysed esterification was proposed to follow a pseudo-homogeneous pathway akin to mineral acid-catalysed esterification, driven by the H(+) ions produced through the hydrolysis of metal complex [Fe(H(2)O)(6)](3+) (aq).
Malaysia has experienced several haze events since the 1980s as a consequence of the transboundary movement of air pollutants emitted from forest fires and open burning activities. Hazy episodes can result from local activities and be categorized as "localized haze". General probability distributions (i.e., gamma and log-normal) were chosen to analyze the PM(10) concentrations data at two different types of locations in Malaysia: industrial (Johor Bahru and Nilai) and residential (Kota Kinabalu and Kuantan). These areas were chosen based on their frequently high PM(10) concentration readings. The best models representing the areas were chosen based on their performance indicator values. The best distributions provided the probability of exceedances and the return period between the actual and predicted concentrations based on the threshold limit given by the Malaysian Ambient Air Quality Guidelines (24-h average of 150 μg/m(3)) for PM(10) concentrations. The short-term prediction for PM(10) exceedances in 14 days was obtained using the autoregressive model.
Matched MeSH terms: Cooking/statistics & numerical data
Several million tones of palm oil and palm olein are used annually in the world for frying. This paper will discuss their frying performances in three major applications - industrial production of potato chips/crisps, industrial production of pre-fried frozen French fries and in fast food outlets. In the first study, about four tones of potato chips were continuously fried 8 hours a day and five days a week. The palm olein used (with proper management) performed well and was still in excellent condition and usable at the end of the trial. This was reflected in its low free fatty acid (FFA) content of around 0.23%, peroxide value of 4 meq/kg, anisidine value of 16, low polar and polymer contents of 10% and 2%, respectively, induction period (OSI) of 21 hours and high content of tocopehrols and tocotrienols of 530 ppm even after >1900 hours. In the second study in which an average 12 tones pre-fried frozen French fries were continuously fried a day for 5 days a week, palm oil performed excellently as reflected by its low FFA of 0.34%, food oil sensor reading of 1.1, low polar and polymer contents of 17% and 2.8%, respectively, over the 12 days of trial. In the third study in which palm shortening, palm oil and palm olein were simultaneously used to intermittently fry chicken parts in the laboratory simulating the conditions in fast food outlets, the three frying oils also performed very satisfactorily as reflected by their reasonably low FFA of <1%, smoke points of >180 degrees C, and polar and polymer contents of <25% and <6%, respectively, after 5 days of consecutive frying. All the quality indicators did not exceed the maximum discard points for frying oils/fats in the three applications, while the fried food product was well accepted by the in-house train sensory panel using a-nine point hedonic score.
Antioxidants are important inhibitory compounds against the oxidative deterioration of food. This study investigated the effects of various phytochemical antioxidant systems [oleoresin rosemary (OR), oleoresin sage (OS) and citric acid (CA)] on the physico-chemical characteristics of refined, bleached and deodorized (RBD) palm olein during the frying of potato chips. The effects of various mixtures of the antioxidants on the oil was also studied in repeated deep frying. The response surface methodology was used to optimize the composition of mixed antioxidants used. A comparative study was carried out with synthetic antioxidants. Samples of the oil after frying were analyzed for different physical and chemical properties. OR and OS were found to be effective phytochemical antioxidants protecting RBD palm olein against oxidative deterioration during frying.
A total of 402 Escherichia coli isolates were obtained from a variety of food samples and screened for enteropathogenic E. coli (EPEC). Screening was carried out using 15 specific monovalent antisera from Murex Diagnostic Limited. A total of 19 E. coli isolates were serotyped as EPEC. The EPEC strains were shown to belong to 8 serotypes. Eight out of 19 EPEC strains belonged to serotype 018C:K77 (B21). Seventeen out of 19 of the EPEC strains were isolated from cooked food. The presence of E. coli in cooked food is an indicator of fecal contamination and a sign of unhygienic food handling. The presence of EPEC in food could be a potential source of food-borne outbreak. Hygiene training for every food-handler is a necessity.
Snail is one of the worst causes of food allergy. Thus, the aim of this study was to identify the major and minor allergens of the local marine snail (Cerithidea obtusa) and subsequently to investigate the impacts of heat treatment on the IgE-binding activity of snail allergens. Proteins from raw and heat-treated snails (boiled, roasted and fried) were extracted and then resolved by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Immunoblotting of all extracts were then performed using sera from patients with snail allergy. The results showed that the raw extract contains numerous protein bands between 12 to>250 kDa. Some thermostable proteins, predominantly the 33 and 42 kDa bands, remained detected in all cooked extracts with decreasing intensities from boiled to roasted to fried extracts, while the majority of thermolabile bands denatured after heating. Boiled snail had more protein bands compared to roasted and fried snails. Immunoblotting of raw extract demostrated 19 IgE-binding bands ranging from 15 to 240 kDa. The thermostable bands of 33 and 42 kDa and a thermolabile of 30 kDa band were identified as the major allergens of this snail. The cooked extracts yielded less allergenic bands. The boiled extract yielded approximately 14 IgE-binding bands with some smeared bands at high molecular weight regions. The roasted extract had lesser IgE-binding bands and the majority appeared as smears, while the IgE-reactivity in the fried extract was less visible and appeared as weak smears. This study indicated that both raw and cooked snails played a crucial role in snail allergenicity, as this species of snail contains both thermostable and thermolabile major allergens. The degree of snail allergenicity was revealed in the order: raw> boiled > roasted> fried. Thus, the results would facilitate in the development of effective diagnosis and management strategies of snail allergy in this country.
This paper describes the influence of different factors on toughness of beef semitendinosus (ST) by means of low temperature-long time cooking with single-stage (60 °C, 65 °C, 70 °C, and 75 °C for 6 h and 12 h) and two-stage sous-vide procedure (45 + 60 °C, 45 + 65 °C, 45 + 70 °C, and 45 + 75 °C; 49 + 60 °C, 49 + 65 °C, 49 + 70 °C, and 49 + 75 °C for 3 h at the first temperature, and either 3 or 9 h at the second temperature). Reduced toughness of ST beef steak muscle could be attained in 6 h at 60 °C and 45 + 60 °C were due from the minimum shrinkage of sarcomere as well as lower perimysial thickness, cooking loss, and elastic modulus. Collagen solubility showed a positive correlation to the toughness values. The relationship between proteolytic activity and shear force can be seen after 12 h of cooking duration. For the other quality attributes, two stepped cooking temperature-time combination seems to be more effective in preserving the redness values and water content than a single-stage sous-vide method.
A process for enhancing textural and cooking properties of fresh rice flour-soy protein isolate noodles (RNS) to match those of yellow alkaline noodles (YAN) was developed by incorporating microbial transglutaminase (RNS-MTG), glucono-δ-lactone (RNS-GDL), and both MTG and GDL into the RNS noodles (RNS-COM). The formation of γ-glutamyl-lysine bonds in RNS-COM and RNS-MTG was shown by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Scanning electron microscope showed that compared to others, the structure of RNS-COM was denser, smoother with extensive apparent interconnectivity of aggregates. The optimum cooking time was in the order: YAN > RNS-COM > RNS-MTG > RNS-GDL > RN (rice flour noodles); tensile strength was in the order: YAN > RNS-COM > RNS-MTG > RNS-GDL > RN; and elasticity were in the order: YAN > RNS-COM > RNS-MTG, RNS-GDL > RN. Overall, RNS-COM showed similar textural and structural breakdown parameters as compared to those of YAN. Changes in microstructures and improvement of RNS-COM in certain properties were likely due to enhanced crosslinking of proteins attributed to MTG- and GDL-induced cold gelation of proteins at reduced pH value. It is possible to use the combination of MTG and GDL to improve textural and mechanical properties of RNS comparable to those of YAN. PRACTICAL APPLICATION: Combined MTG and GDL yield rice flour noodles with improved textural properties. The restructured rice flour noodles have the potential to replace yellow alkaline noodles.
Zero-salted yellow alkaline noodles (YAN) were immersed in solutions of resistant starch HYLON™ VII (HC) or fruit coating Semperfresh™ (SC) containing a range of salt (NaCl) between 10 and 30% (w/v). The objective was to evaluate the effect of salt-coatings on the textural, handling, cooking, and sensory properties of YAN. Increasing salt in the coatings caused a reduction in optimum cooking time, cooking loss and increase in cooking yield. The mechanical and textural parameters, sensory hardness, springiness and overall sensory acceptability of the salt-coated noodles however decreased with increasing salt application. HC-Na10 and SC-Na10 showed the highest textural and mechanical parameters, sensory hardness and springiness. The differences in the parameters were attributed mainly to the water absorption properties of starch that was affected by salt application. Thus, the quality of salt-coated noodles was dependent mainly on the amounts of salt applied in the coatings rather than on the types of coatings used.
Low vegetable consumption in children is always a matter of concern. The aim of this study was to determine the effect of multiple exposures on acceptance of a test vegetable among preschoolers aged 6 years.
3-Monochloropropane-1,2-diol (3-MCPD) esters and glycidyl esters (GE) are heat-induced contaminants which form during oil refining process, particularly at the high temperature deodorization stage. It is worth to investigate the content of 3-MCPD and GE in fries which also involved high temperature. The content of 3-MCPD esters and GE were monitored in fries. The factors that been chosen were temperature and duration of frying, and different concentration of salt (NaCl). The results in our study showed that the effect was in the order of concentration of sodium chloride
The method of liquid chromatographic tandem mass spectrometry was utilized and modified to confirm and quantify acrylamide in heating cooking oil and animal fat. Heating asparagine with various cooking oils and animal fat at 180°C produced varying amounts of acrylamide. The acrylamide in the different cooking oils and animal fat using a constant amount of asparagine was measured. Cooking oils were also examined for peroxide, anisidine and iodine values (or oxidation values). A direct correlation was observed between oxidation values and acrylamide formation in different cooking oils. Significantly less acrylamide was produced in saturated animal fat than in unsaturated cooking oil, with 366ng/g in lard and 211ng/g in ghee versus 2447ng/g in soy oil, followed by palm olein with 1442ng/g.
The impact of microwave roasting on the thermooxidative degradation of perah seed oil (PSO) was evaluated during heating at a frying temperature (170°C). The roasting resulted significantly lower increment of the values of oxidative indices such as free acidity, peroxide value, p-anisidine, total oxidation (TOTOX), specific extinctions and thiobarbituric acid in oils during heating. The colour L* (lightness) value dropped gradually as the heating time increased up to 12 h, whereas a*(redness) and b* (yellowness) tended to increase. The viscosity and total polar compound in roasted PSO was lower as compared to that in unroasted one at each heating times. The tocol retention was also high in roasted samples throughout the heating period. The relative contents of polyunsaturated fatty acids (PUFAs) were decreased to 94.42% and saturated fatty acids (SFAs) were increased to 110.20% in unroasted sample, after 12 h of heating. On the other hand, in 3 min roasted samples, the relative contents of PUFAs were decreased to 98.08% and of SFAs were increased to 103.41% after 12 h of heating. Outcome from analyses showed that microwave roasting reduced the oxidative deteriorations of PSO during heating.