Effect of mass on convective heat transfer coefficient during open sun drying of groundnut.
In this work, an attempt is made to study the effect of mass on convective heat transfer coefficient (CHTC) for open sun drying (OSD) of groundnut (Arachis hypogaea L.). Experiments were conducted during the month of May, 2016 in the climatic condition of Rohtak, India (28°54'0″N 76°34'0″E). Groundnut samples of 130 and 198 g were dried under OSD condition till almost no variation in its mass was recorded. Hourly data of the mass evaporated, groundnut temperature, relative humidity and ambient temperature were recorded. The experimental data obtained were used to determine the constants 'C' and 'n' in the Nusselt number expression using linear regression method. CHTC increased with the increase in mass of groundnuts. The experimental errors in terms of percent uncertainty were found to vary from 44.29 to 48.77%.
Peanuts, Aflatoxins and Undernutrition in Children in Sub-Saharan Africa.
Peanuts (Arachis hypogaea) is an important and affordable source of protein in most of Sub-Saharan Africa (SSA) and a popular commodity and raw material for peanut butter, paste and cooking oil. It is a popular ingredient for foods used at the point of weaning infants from mother's milk. It is at this critical point that childhood undernutrition occurs and the condition manifests as stunting, wasting and growth restriction and accounts for nearly half of all deaths in children under five years of age in SSA. Undernutrition is multi-factorial but weaning foods contaminated with microbiological agents (bacteria and fungi) and natural toxins have been shown to play a big part. While peanuts may provide good nutrition, they are also highly prone to contamination with mycotoxigenic fungi. The high nutritive value of peanuts makes them a perfect substrate for fungal growth and potential aflatoxin contamination. Aflatoxins are highly carcinogenic and mutagenic mycotoxins. This article reviews the nutritional value and aflatoxin contamination of peanuts, the role they play in the development of childhood malnutrition (including the different theories of aetiology) and immunological problems in children. We also discuss the control strategies that have been explored and advocacy work currently taking shape in Africa to create more awareness of aflatoxins and thus combat their occurrence with the goal of reducing exposure and enhancing trade and food safety.
Evaluation of peanut skin and grape seed extracts to inhibit growth of foodborne pathogens.
Peanut skin extract (PSE) and grape seed extract (GSE) are derived from waste products in the wine and peanut industries, respectively. Both have high concentrations of polyphenols, known to possess antioxidant and antimicrobial properties. PSE primarily contains "A-type" procyanidins, while GSE primarily contains "B-type" procyanidins. These differ structurally, but are both isomers of epicatechin dimers. The objective of this study was to evaluate the antimicrobial effects of PSE containing A-type procyanidins and GSE containing B-type procyanidins against select foodborne pathogens (Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Typhimurium). The minimum inhibitory concentration (MIC) of the two extracts on L. monocytogenes, E. coli O157:H7, and S. Typhimurium was determined using the pour plate method. GSE had a significantly lower MIC (p ≤ .05) than PSE for L. monocytogenes (GSE = 60.6 ppm, PSE > 68.2 ppm) and S. Typhimurium (GSE = 45.7 ppm, PSE = 60.6 ppm), but no difference in inhibition of E. coli O157:H7. Since GSE contributed to greater inhibition, GSE extract was fractionated into monomer-rich (consisting primarily of catechins, epicatechins, and epicatechin gallates) and oligomer-rich (consisting of dimers, trimers, tetramers, up to decamers) components. Growth curves of all three pathogens in the presence of full extract, monomer and oligomer fractions were compared separately. None of the extracts inhibited S. Typhimurium growth. Generally, the extract containing greater oligomer components inhibited growth of L. monocytogenes and E. coliO157:H7 when compared to the control. Results indicate that an extract with type B procyanidins higher in oligomers may have greater antimicrobial properties.
Suppression of aflatoxin production in Aspergillus species by selected peanut (Arachis hypogaea) stilbenoids.
Aspergillus flavus is a soil fungus that commonly invades peanut seeds and often produces the carcinogenic aflatoxins. Under favorable conditions, the fungus-challenged peanut plant produces and accumulates resveratrol and its prenylated derivatives in response to such invasion. These prenylated stilbenoids are considered peanut antifungal phytoalexins. However, the mechanism of peanut-fungus interaction has not been sufficiently studied. We used pure peanut stilbenoids, arachidin-1, arachidin-3, and chiricanine A to study their effect on the viability and metabolite production by several important toxigenic Aspergillus species. Significant reduction, or virtually complete suppression of aflatoxin production was revealed in feeding experiments in A. flavus, A. parasiticus, and A. nomius. Changes in morphology, spore germination and growth rate were observed on A. flavus exposed to selected peanut stilbenoids. Elucidation of the mechanism of aflatoxin suppression by peanut stilbenoids could provide strategies for preventing plant invasion by the fungi that produce aflatoxins.
Characterization of Peanut Oil Bodies Integral Proteins, Lipids, and Their Associated Phytochemicals.
A microscopic image of a section of a peanut seed shows that oil bodies (OBs) are a small droplet of oil that is dispersed throughout the whole seed. The protein profile of peanut's OBs recovered using the aqueous extraction method at different pH was found to have 2 oleosin isoforms of 14 and 16 kDa. Moreover, OBs essential amino acids are 1.52 higher than those in the PPI. Oleic acid and linoleic acid are the major fatty acids in both cold press peanut oil and OBs regardless of pH. Tocopherol content went from 270.76 to 278.2 mg/g when pH got increased. δ-Tocopherols are slightly associated with peanut OBs, as it was resistant to the alkaline washing; however, α-tocopherols were discovered to be weakly associable. On the contrary, phytosterols content decreased when pH got increased, with 631.49 μg/g for pH 6.8 and 614.96 μg/g for pH 11.0. PRACTICAL APPLICATION: Peanut oil is widely used in food industries in the form of emulsified oil. OBs can be presented as a better alternative solution, which is stable emulsified oil, with high content of antioxidant and phytosterols. Our results showed that peanut OBs are rich in nutritional components such as essential amino acids, unsaturated fatty acids, vitamin E, and phytosterols. Moreover, peanut OBs are surrounded with 2 oleosin isoforms and caleosin, which offer more stability to the emulsion system. Thus, peanut OBs can be perfect for food like mayonnaise and vinaigrettes products in the form of encapsulated oil with high content of vitamin E.
Effects of high hydrostatic pressure on the functional and rheological properties of the protein fraction extracted from pine nuts.
High hydrostatic pressure treatments could increase the protein solubility (200 MPa), water holding capacity (400 MPa), and oil holding capacity (400 MPa) of pine nuts protein fractions, respectively. The exposed sufhydryl content for albumin was highest at 100 MPa while for other fractions it was 400 MPa, contrary for total sufhydryl content-generally it was at 100 MPa, except glutelin (400 MPa). Pine nuts protein fractions demonstrated the typical behavior of weak gels (G' > G″). After the treatments of high hydrostatic pressure the specific surface area of pine nuts protein particle was increased upon pressure, and the surface of protein became rough which increased the particle size. The functional groups of protein were found to be unchanged, but the characteristic peaks of pine nuts protein moved to a low-band displacement and the value of peaks was amplified accordingly to the pressure. The high hydrostatic pressure treatments were found to improve the functional properties of pine nuts protein isolates by enhancing the heat-induced gel strength of pine nuts protein isolates which make proteins more stretchable. These results suggest that high hydrostatic pressure treatments can increase the functional properties and alter the rheological properties of pine nuts protein fractions which will broaden its applications in food industry.
Effect of natural polyphenol on the oxidative stability of pecan oil.
We evaluated the antioxidant activity of natural polyphenols which gives high oxidative stability to the pecan oil. The in vitro DPPH radical scavenging, reducing power and total antioxidant activity of tested antioxidants demonstrated that tannic acid displayed the highest DPPH scavenging activity and provided the largest reducing power. During storage of pecan oil, based on oxidative stability tests, we further evaluated the protective effect of polyphenols and synthetic antioxidants on the oxidative stability of pecan oil. The results showed that caffeic acid inhibited oxidation of pecan oil effectively. Sesamol and catechin showed slight improvement in oxidative stability, while ferulic acid, erucic acid and rutin had no effect. Taken together, compared with synthetic antioxidants (TBHQ, BHT, BHA), caffeic acid was observed to be stronger than BHT and BHA and was close to TBHQ.
Fatty acid profile of pecan nut oils obtained from pressurized n-butane and cold pressing compared with commercial oils.
This short note compares the chemical profile of pecan nut oil samples obtained from pressurized n-butane and cold pressing with two commercial oils. The conventional cold pressing technique yielded 58.9 wt%, while pressurized n-butane yielded from 53 to 65 wt%, being the highest yield at 55 °C, and pressure of 40 bar. The n-butane behaves nearly like a piston fluid within the experimental conditions used. The results showed that the extraction variables had a slight influence on the fatty acid composition of the samples. Extraction with n-butane thus showed to be a promising alternative technique to conventional extraction methods, as very mild operating conditions and eco-friendly solvent can be used to provide good results without any residues in the final product.
Pecan walnut (Carya illinoinensis (Wangenh.) K. Koch) oil quality and phenolic compounds as affected by microwave and conventional roasting.
In this study, the effects of conventional and microwave roasting on phenolic compounds, free acidity, peroxide value, fatty acid composition and tocopherol content of pecan walnut kernel and oil was investigated. The oil content of pecan kernels was 73.78% for microwave oven roasted at 720 W and 73.56% for conventional oven roasted at 110 °C. The highest free fatty acid content (0.50%) and the lowest peroxide value (2.48 meq O2/kg) were observed during microwave roasting at 720 W. The fatty acid profiles and tocopherol contents of pecan kernel oils did not show significant differences compared to raw samples. Roasting process in microwave oven at 720 W caused the reduction of some phenolic compounds, while the content of gallic acid exhibited a significant increase.
A critical approach to the toxic metal ion removal by hazelnut and almond shells.
The adsorption capacity of ground hazelnut (HS) and almond (AS) shells towards Pb(II) and Cd(II) has been studied at pH = 5, in NaNO3 and NaCl ionic media, in the ionic strength range 0.05-0.5 mol L-1. Kinetic and equilibrium experiments were carried out by using the Differential Pulse Anodic Stripping Voltammetry technique to check the amount of the metal ion removed by HS and AS materials. Different kinetic and equilibrium equations were used to fit experimental data and a statistical study was done to establish the suitable model for the data fitting. A speciation study of the metal ions in solution was also done in order to evaluate the influence of the ionic medium on the adsorption process. TGA-DSC, FT-IR, and SEM-EDX techniques were used to characterize the adsorbent materials. The mechanism of metal ions adsorption was explained on the basis of the results obtained by the metal ions speciation study and the characterization of materials.