Flavor Fade in Peanuts During Short-term Storage

ABSTRACT: Flavor characteristics of roasted peanuts over short-term storage were explored through sensory and chemical analyses. The volatiles from freshly roasted peanuts were evaluated over short-time (21 d) storage using gas chromatography, chemosensory techniques, and a sensory panel to quantify and identify pyrazines and hexanal over a 21-d storage period. A significant decrease ( P < 0.05) was noted in 2,3-diethylpyrazine, 2-methoxypyrazine, 2,3-dimethylpyrazine, 2-ethyl-3-methylpyrazine, and 2,3,5-trimethylpyrazine concentrations over a 21-d period. No significant difference ( P > 0.05) was noted in the 2-methylpyrazine and 2-ethylpyrazine concentrations. The hexanal concentration significantly increased ( P < 0.05) over the 21-d period. The peroxide values and sensory analysis agreed with these results. A significant increase ( P < 0.05) in peroxide value was seen at days 14 and 21, and a significant decrease ( P < 0.05) in fresh roasted peanuty flavor from day 0 to 21 and significant increases ( P < 0.05) in painty, cardboardy, and bitter flavors from day 7 to 21 with the sensory analysis. The electronic nose successfully separated day 0 and 21 samples from day 7 and 14 samples, which were also separated but with some overlap.     

Microwave-assisted extraction of phenolic antioxidant compounds from peanut skins

A microwave-assisted extraction system was used to extract phenolic antioxidants from peanut skins. The effects of microwave power (10%, 50%, 90% nominal), irradiation time (30, 90, 150 s) and sample mass (1.5, 2.5, 3.5 g) on total phenolic content (TPC), ORAC (oxygen radical absorbance capacity) level and resveratrol content of peanut skin extracts (PSE) were investigated. Peanut skins were extracted with 37.5 ml of 30% ethanol (EtOH) in water. A response surface method was used to estimate optimum extraction conditions, based on TPC, ORAC level and resveratrol content. The maximum predicted TPC, under the optimised conditions (90% microwave power, 30 s irradiation time and 1.5 g skins), was 143.6 mg gallic acid equivalent (GAE)/g skins. The highest ORAC value was 2789 μmol trolox equivalents (TE)/g skins, which occurred at 90% power, 150 s and 1.5 g of skins. Resveratrol was identified in PSE by LC–MS–MS analysis.     

Optimum conditions for beef carcass chilling

Optimum chilling schemes for a two- or three-stage chilling system were developed using a validated heat and mass transfer model and a pattern search algorithm. The optimization was performed for the ambient temperature during each stage for an air velocity of 0·5 m/s and 90% relative humidity. The experiments were conducted to evaluate the effect of the optimum conditions on beef quality after ageing.     

Effect of ionizing radiation on structural and functional attributes of red kidney bean (Phaseolus vulgaris L.) lectin

Gamma radiation inactivation of phytohemagglutinin (PHA) of red kidney bean in purified form as well as in seeds in different moisture conditions was demonstrated at different doses viz. 1, 10, 30, 50, 100 and 200 kGy. Irradiation of PHA in dry state (99.5% dry) or in 50% moisture condition showed structural intactness as studied by SDS–PAGE, size exclusion chromatography (SEC), fluorescence measurement, CD spectroscopy below 30 kGy, while a 50% reduction in hemagglutinin and mitogenic activity was observed in the dose range of 30–50 kGy. Radiation inactivation of purified PHA was more pronounced when irradiated in aqueous solution form resulting in complete destruction of secondary and tertiary structure as well as function at a dose of 10 kGy. Radiation processing of dry and soaked seeds of kidney bean exhibited 50% loss in functional activity of PHA at the doses of 50 and 30 kGy, respectively. Practicality of implication of the radiation processing for inactivation of this antinutrient in legume seeds is discussed.     

Studies on the anodic dissolution of copper matte

Anodic polarisation studies on copper matte revealed that a copper matte electrode polariess abruptly in H,SO, solution but not in HCl solution. Anodic dissolution of copper matte was studied at various anodic potentials in 2 N solutions of HCl and H,SO,. It was found that at lower anodic potential (around 0.4 volt vs. saturated calomel electrode) copper dissolves preferentially (at 90% current efficiency) over iron (8–10% C.E.), in both the acid solutions. It was further observed that this preferential dissolution of copper takes place over a longer period (about 6 h) in HCl than in H₂SO₄ solution (about 3 h). Preferential dissolution of copper from copper matte was found to be independent of HCl concentration (0.5 N to 4 N). From the X-ray diffraction analysis of the original copper matte and electrolysed copper matte, it was established that digenite and bornite phases of copper matte dissolved causing preferential dissolution of copper.     

Supercritical fluid extraction of lipids from deep-fried food products

A supercritical fluid extraction (SFE) method is described for extracting lipids from fried-food samples. Response surface analysis was used to study the effects of variables, including pressure, temperature, flow rate, and modifier (methanol) on lipid extraction by SFE. The analysis of variance for the response variables indicated that the models developed were satisfactory with coefficients of determination of 0.95 and 0.92 for chicken nuggets and potato fries, respectively. The models predicted that increasing the pressure increased the percentage lipid extracted for both chicken nuggets and potato fries. In addition, the pressure by temperature interactions were significant for chicken nuggets and potato fries. Slight differences in fatty acid composition were observed between SFE and the Goldfisch method. The SF extracts contained traces of C_12:0, C_20:0, and C_24:0 in chicken nuggets and C_14:1, C_18:3, C_22:0, and C_23:0 in potato fries, respectively, which are not found in the Goldfisch extracts. The optimal conditions for extraction are: 53 MPa, 150°C, 4 mL/min, and 10% modifier for chicken nuggets and 53 MPa, 150°C, 3 mL/min, and 0% modifier for potato fries. To duplicate the results of exhaustive Goldfisch extraction with petroleum ether, SFE conditions of 44 MPa, 80°C, 3 mL/min, and 0% modifier were used to produce similar results for both chicken nuggets and potato fries.     

Prevalence of aflatoxin contamination in red chilli pepper (Capsicum annum L.) from India

The aflatoxin contamination of chilli pepper grown and marketed in Tamil Nadu, a southern Indian state, was assessed. Chilli samples were collected at different stages of the value chain and were quantified using the enzyme-linked immunosorbent assay (ELISA) test. Forty-two representative samples were collected from four districts identified as the hub for production, distribution, agro-processing industries and retail stores. In addition, interviews were conducted among the chilli farmers, vendors and agro-industrialists across the hubs to assess their knowledge on aflatoxin contamination and safe handling practices. The maximum aflatoxin content determined in the chilli pepper was 37.8 µg kg⁻¹. Almost 66.7% of samples collected from the retail outlets had aflatoxin values above 10 µg kg⁻¹. The total aflatoxin content in the samples collected across the value chain was in the range of 3.83 to 37.80 µg kg⁻¹. Statistical analysis on aflatoxin contents showed that there were significant differences (P < 0.05) between the districts representing different operations of value chain. The detected aflatoxin content was highest in samples collected from Dindigul district and least in Erode district. The results of the perception study showed that respondents into farming and trade activities had very little or no knowledge of aflatoxin contamination of chilli. The prevalence of unacceptable levels of aflatoxin in the chilli supply chain in the districts studied is probably due to tropical climatic conditions and poor handling practices of chilli.