Peanut Kernels Research Articles

Association of a Burrower Bug (Heteroptera: Cydnidae) with Aflatoxin Contamination of Peanut Kernels

Aflatoxin contamination of peanut kernels, Arachis hypogaea L., was associated with feeding by a burrower bug, Pangaeus bilineatus (Say). Kernel samples were divided into three grade categories: total sound mature kernels (TSMK), other kernels (OK), and damaged kernels (DK); and each of these grade categories was subdivided based on evidence of burrower bug feeding. Within TSMK, 100% of detectable aflatoxin contamination was associated with burrower bug kernel feeding, and kernels with feeding sites had a significantly higher concentration of aflatoxin than kernels without feeding sites (7.5 vs 0.0 ppb). Within the OK grade category, differences in aflatoxin contamination were not significant due to the inability to conclusively examine these kernels for feeding sites. Within the DK grade category, aflatoxin concentration was significantly higher in kernels with feeding sites than in kernels without observable feeding sites (286.5 vs 0.4 ppb), and 99.9% of contamination was associated with burrower bug feeding. Across all grade categories, aflatoxin levels were 65X higher in kernels with observable burrower bug feeding, and 98% of all aflatoxin contamination was associated with burrower bug feeding. The DK grade category had the highest concentration of aflatoxin and accounted for 45% of total contamination. Burrower bug-induced aflatoxin contamination of the TSMK grade category is particularly significant because this source would be most difficult to remove from the food supply. Contamination of the DK category is also economically significant because this grade component is specifically examined for Aspergillus at the buying point, and growers are severely penalized for detection.

Lipase‐catalyzed alcoholysis of vegetable oils

AbstractFatty acid alkyl esters were produced from various vegetable oils by transesterification with different alcohols using immobilized lipases. Using n‐hexane as organic solvent, all immobilized lipases tested were found to be active during methanolysis. Highest conversion (97%) was observed with Thermomyces lanuginosa lipase after 24 h. In contrast, this lipase was almost inactive in a solvent‐free reaction medium using methanol or 2‐propanol as alcohol substrates. This could be overcome by a three‐step addition of methanol, which works efficiently for a range of vegetable oils (e.g. cottonseed, peanut, sunflower, palm olein, coconut and palm kernel) using immobilized lipases from Pseudomonas fluorescens (AK lipase) and Rhizomucor miehei (RM lipase). Repeated batch reactions showed that Rhizomucor miehei lipase was very stable over 120 h. AK and RM lipases also showed acceptable conversion levels for cottonseed oil with ethanol, 1‐propanol, 1‐butanol and isobutanol (50‐65% conversion after 24 h) in solvent‐free conditions. Methyl and isopropyl fatty acid esters obtained by enzymatic alcoholysis of natural vegetable oils can find application in biodiesel fuels and cosmetics industry, respectively.

Manual Sorting To Eliminate Aflatoxin from Peanuts

A manual sorting procedure was developed to eliminate aflatoxin contamination from peanuts. The efficiency of the sorting process in eliminating aflatoxin-contaminated kernels from lots of raw peanuts was verified. The blanching of 20 kg of peanuts at 140°C for 25 min in preheated roasters facilitated the manual sorting of aflatoxin-contaminated kernels after deskinning. The manual sorting of raw materials with initially high aflatoxin contents (300 ppb) resulted in aflatoxin-free peanuts (i.e., peanuts in which no aflatoxin was detected). Verification procedures showed that the sorted sound peanuts contained no aflatoxin or contained low levels (<15 ppb) of aflatoxin. The results obtained confirmed that the sorting process was effective in separating contaminated peanuts whether or nor contamination was extensive. At the commercial level, when roasters were not preheated, the dry blanching of 50 kg of peanuts for 45 to 55 min facilitated the proper deskinning and subsequent manual sorting of aflatoxin-contaminated peanut kernels from sound kernels.

Burrower Bugs (Heteroptera: Cydnidae) in Peanut: Seasonal Species Abundance, Tillage Effects, Grade Reduction Effects, Insecticide Efficacy, and Management

Pitfall traps placed in South Carolina peanut, Arachis hypogaea (L.), fields collected three species of burrower bugs (Cydnidae): Cyrtomenus ciliatus (Palisot de Beauvois), Sehirus cinctus cinctus (Palisot de Beauvois), and Pangaeus bilineatus (Say). Cyrtomenus ciliatus was rarely collected. Sehirus cinctus produced a nymphal cohort in peanut during May and June, probably because of abundant henbit seeds, Lamium amplexicaule L., in strip-till production systems. No S. cinctus were present during peanut pod formation. Pangaeus bilineatus was the most abundant species collected and the only species associated with peanut kernel feeding injury. Overwintering P. bilineatus adults were present in a conservation tillage peanut field before planting and two to three subsequent generations were observed. Few nymphs were collected until the R6 (full seed) growth stage. Tillage and choice of cover crop affected P. bilineatus populations. Peanuts strip-tilled into corn or wheat residue had greater P. bilineatus populations and kernel-feeding than conventional tillage or strip-tillage into rye residue. Fall tillage before planting a wheat cover crop also reduced burrower bug feeding on peanut. At-pegging (early July) granular chlorpyrifos treatments were most consistent in suppressing kernel feeding. Kernels fed on by P. bilineatus were on average 10% lighter than unfed on kernels. Pangaeus bilineatus feeding reduced peanut grade by reducing individual kernel weight, and increasing the percentage damaged kernels. Each 10% increase in kernels fed on by P. bilineatus was associated with a 1.7% decrease in total sound mature kernels, and kernel feeding levels above 30% increase the risk of damaged kernel grade penalties.

CONTROL OF AFLATOXIGENIC Aspergillus flavus IN PEANUTS USING NONAFLATOXIGENIC A. flavus, A. niger and Trichoderma harzianum

The effects of nontoxigenic Aspergillus flavus, A. niger and Trichoderma harzianum inoculated into planting media on toxigenic A. flavus infection and its aflatoxin production in peanut kernels at harvest were investigated together with (1) the moisture content of planting media before peanut planting, at the time of inflorescence, and at harvest, (2) the population of aflatoxigenic and nonaflatoxigenic A. flavus, A. niger and T. harzianum in peanut planting media before peanut planting, at the time of inflorescence, and at harvest, (3) the moisture content of peanut kernels at harvest, and (4) toxigenic A. flavus invasion in peanut plant parts (roots, stems, petioles, leaves and flowers) at the time of inflorescence. The fungal isolates were inoculated into planting media at the same time with the planting of peanut seeds. Peanut plants were grown under glasshouse conditions. Treated planting media were inoculated with the combined use of (1) toxigenic and nontoxigenic A. flavus, (2) toxigenic A. flavus and A. niger, and (3) toxigenic A. flavus and T. harzianum. Planting media inoculated only with each fungal isolate and uninoculated planting media were used as controls. Two watering treatments of peanut plants were carried out, i.e. watering until harvest and not watering for 15 days before harvest. The populations of the fungal isolates in the planting media and peanut kernels were determined using dilution method followed by pour plate method; the percentages of toxigenic A. flavus and test fungal colonizations in peanut plant parts were determined using plating method; the moisture content of planting media and peanut kernels were determined using oven method; the aflatoxin content of peanut kernels was determined using Thin Layer Chromatography method. The results indicated that at the time of harvest the decrease in moisture contents of planting media not watered for 15 days before harvest was higher than those watered until harvest. The lowest population of toxigenic A. flavus was in planting media inoculated with the combined use of toxigenic and nontoxigenic A. flavus at the time of inflorescence and at the time of harvest. Toxigenic A. flavus could invade the roots, stems and flowers of peanut plants. The lowest percentage of invasion was on the plant parts which planting media were inoculated with the combined use of toxigenic and nontoxigenic A. flavus. The moisture content of peanut kernels originated from watered plants until harvest were higher than those not watered for 15 days before harvest. The population of toxigenic A. flavus in peanut kernels derived from the plants whose planting media were inoculated with the combined use of toxigenic A. flavus and each test fungi, was lower than those inoculated only with toxigenic A. flavus. It indicated that the test fungi inoculated into planting media could inhibit toxigenic A. flavus infection in peanut kernels. Aflatoxin was only detected in peanut kernels originated from one plant whose planting medium was inoculated only with toxigenic A. flavus and the plant was watered until the time of harvest. Toxigenic A. flavus infection and aflatoxin production were not influenced by planting media which were not watered for 15 days before harvest. Keywords: Biocontrol / Aflatoxigenic / Nonaflatoxigenic / Aspergillus flavus I Aspergillus niger I Trichoderma harzianum I Peanuts

Reduction of mutagenicity of the fumes from cooking oil by degumming treatment

The fume of cooking oil has been reported to increase the risk of respiratory tract cancer. The influence of a degumming treatment of peanut oil on the contents of mutagenic compounds in fumes from heated peanut oil was investigated. The results indicate that the peanut oil prepared from roasted peanut kernels which underwent degumming treatment had a lower free fatty acid (FFA) content and a higher smoke point, was more clear in color, and produced less fumes when heated at smoke point. Moreover, when compared to untreated peanut oil, the mutagenicity of oil fumes of degummed peanut oil toward Salmonella typhimurium TA98 and TA100 was reduced to 81% and 73% ( p<0.05), respectively. The degummed peanut oil which was obtained by adding 3% water and heating at 60°C for 20 min produced the least amount of mutagenic fume. The contents of four mutagenic compounds, trans-trans-2,4-decadienal ( t-t-2,4-DDE), trans-trans-2,4-nonadienal ( t-t-2,4-NDE), trans-2-decenal ( t-2-DCA), and trans-2-undecenal ( t-2-UDA) in oil fumes of degummed peanut oils were drastically decreased ( p<0.05), especially the t-t-2,4-DDE. The results also indicate that the FFA content had a high linear correlation with mutagenicity ( r 2=0.9978) and content of t-t-2,4-DDE ( r 2=0.7685). Moreover, there was a correlation ( r 2=0.7816) between the content and the mutagenicity of t-t-2,4-DDE. The decrease of FFA by degumming might explain the reduction of mutagenic alkenal compounds and mutagenicity of fumes from heated peanut oil.

Blanchability of peanut (Arachis hypogaea L.) kernels: early generation selection and genotype stability over three environments

Blanching is the removal of testa from peanut kernel by heating followed by abrasion. Blanchability is the capacity to recover kernels with all the testa removed. This study investigated the response to early generation selection for blanchability and the stability of 22 breeding lines over 3 environments.F2-derived families with 'good' and 'poor' blanchability were selected. BLUPs for F4:5 lines from F2 families were significantly correlated with the mean blanchability of F2:3 rows. The within-family variance was mostly in 3�of the poor blanching families. In all other families, variance among lines within families was smaller than the error variance. Early generation selection was effective.In the 22 lines × 3 site experiment, there was a high genetic correlation common to each pair of sites, suggesting that differences in blanchability are repeatable. The expression of genetic variation was much greater at Coominya, with a 5-fold greater genetic variance than at Walkamin. All 3 environments in this experiment were irrigated. Interaction may have been greater with the inclusion of rainfed environments.Parent selection could make an important contribution to breeding for improved blanchability. Environment may not substantially affect the rank of genotypes but may affect the capacity to detect differences.

FUNGAL POPULATION, AFLATOXIN AND FREE FATTY ACID CONTENTS OF PEANUTS PACKED IN DIFFERENT BAG TYPES

Shelled peanuts of Gajah var. with initial moisture content of 7% were stored at 11 kg/bag in four bag types namely: jute bag, polypropylene bag, jute bag doubled with thin polyethylene (PE), and jute bag doubled with thick PE. Storage was done for six months under warehouse conditions with monitoring of relative humidity and temperature. Samples taken at the beginning of storage and every month thereafter were analyzed for moisture content, fungal population, aflatoxin and free fatty acid contents. Statistical analyses showed that moisture content, fungal population, and free fatty acid contents were significantly higher in jute and polypropylene bags than in PE-dou,bled jute bags. No significant differences were obtained in aflatoxin contents among bag types but at the end of six months storage, toxin level in jute bag exceeded the 30 ppb limit. Polypropylene had second highest toxin level at 23 ppb. The PE-doubled bags had 17 and 19 ppb total aflatoxins for thin and thick films, respectively. The results indicated that the immediate packaging of dried shelled peanuts at safe moisture level in plastic films with water vapor transmission rated of 1 g/m2/24 hr or lower is recommended. This packaging will delay critical increases in moisture content, fungal population, aflatoxin and free fatty acid contents of peanut kernels at ambient storage conditions. Keywords: Peanuts / bag types / fungal population / aflatoxin content / free fatty acid content.

Polymerase Chain Reaction–Mediated Characterization of Molds Belonging to the Aspergillus flavus Group and Detection of Aspergillus parasiticus in Peanut Kernels by a Multiplex Polymerase Chain Reaction

The Aspergillus flavus group covers species of A. flavus and Aspergillus parasiticus as aflatoxin producers and Aspergillus oryzae and Aspergillus sojae as koji molds. Genetic similarity among these species is high, and aflatoxin production of a culture may be affected by cultivation conditions and substrate composition. Therefore, a polymerase chain reaction (PCR)-mediated method of detecting the aflatoxin-synthesizing genes to indicate the degree of risk a genotype has of being a phenotypic producer was demonstrated. In this study, 19 strains of the A. flavus group, including A. flavus, A. parasiticus, A. oryzae, A. sojae, and one Aspergillus niger, were subjected to PCR testing in an attempt to detect four genes, encoding for norsolorinic acid reductase (nor-1), versicolorin A dehydrogenase (ver-1), sterigmatocystin O-methyltransferase (omt-1), and a regulatory protein (apa-2), involved in aflatoxin biosynthesis. Concurrently, the strains were cultivated in yeast-malt (YM) broth for aflatoxin detection. Fifteen strains were shown to possess the four target DNA fragments. With regard to aflatoxi-genicity, all seven aflatoxigenic strains possessed the four DNA fragments, and five strains bearing less than the four DNA fragments did not produce aflatoxin. When peanut kernels were artificially contaminated with A. parasiticus and A. niger for 7 days, the contaminant DNA was extractable from a piece of cotyledon (ca. 100 mg), and when subjected to multiplex PCR testing using the four pairs of primers coding for the above genes, they were successfully detected. The target DNA fragments were detected in the kernels infected with A. parasiticus, and none was detected in the sound (uninoculated) kernels or in the kernels infected with A. niger.

Dissipation of monosodium methane arsonate (MSMA) on peanuts.

Monosodium methane arsonate (MSMA), the salt of methylarsonic acid (MAA), is a herbicide commonly used to control weeds along roadsides, in cotton, in turf, and on noncrop sites. In recent years questions have arisen regarding the source and nature of arsenic residues in raw agricultural commodities relative to misuse, inadvertent exposure, or rotational crop residues. Field experiments were conducted to determine the fate of MSMA that is applied to peanut foliage. Persistence, dissipation, recovery, and detection of MAA from leaf rinsate were characterized as well as resulting total arsenic and MAA concentrations in peanut kernels. MSMA was applied to peanut foliage at 105, 210, 315, and 420 g of active ingredient (ai)/ha. Peanut leaves were sampled before and after irrigation events over the next 7 days. Peanuts were harvested at maturity and analyzed for MAA and total arsenic. A confined rotational crop experiment was conducted to determine the potential for MAA residues in soil to be taken up by peanuts in fields rotated from cotton that was treated with MSMA. MAA was not detected in any peanut samples from the rotational crop experiment, even when peanuts were planted only 30 days after MSMA application to the soil at 2.24 kg of ai/ha. Field experiments showed that MSMA recovery from leaves with an aqueous rinse declined quickly but was not greatly affected by irrigation. However, quantifiable amounts of MAA were present 1 week after application and after two irrigation events, and MAA and total arsenic were measured in mature peanut kernels from all plots that received MSMA. MAA was not detected in untreated checks. Total arsenic was below the limit of quantification in untreated controls.

Management practices to minimise pre-harvest aflatoxin contamination in Australian peanuts

Aflatoxin contamination in peanut kernels is a serious food safety issue throughout the world. Stringent implementation of the international regulatory limits for aflatoxin contamination has become a major factor affecting the economic viability of dryland peanut growers in regional Queensland. In this study, the effect of time of harvesting (digging) and threshing on kernel yield, seed grades, aflatoxin contamination and gross returns were examined with peanut (cv. Streeton), grown in large-scale on-farm trials in the Burnett District of Queensland, during the 1997-98 and 1999-2000 seasons. Aflatoxin contamination was widespread during the 1997-98 season because of a severe and prolonged end-of-season drought and associated elevated soil temperatures. During the 1999-2000 season, aflatoxin risk was low at 2 sites because of well-distributed rainfall and lower soil temperatures, in contrast to the other 2 sites where the risk was higher. In both seasons, early harvest and threshing under high aflatoxin risk conditions resulted in consistently lower aflatoxin concentrations and higher gross returns (up to 27%) than in delayed harvesting treatments. However, under low aflatoxin risk conditions crops could be left longer to realise higher potential yield and better seed grades. Indeed, early harvest under low aflatoxin risk resulted in lower gross returns because of lower yields and poorer seed grades. The current study highlighted the importance of assessing aflatoxin risk on a site-by-site basis in order to make appropriate decisions on timing of harvest so as to minimise aflatoxin contamination and maximise gross returns from dryland peanuts.

CURING PEANUTS USING CONTINUOUS FLOW DRYERS

A two–year study was conducted to determine the potential for curing peanuts using continuous flow dryers with minimal detrimental effects on quality. A single–pass continuous flow dryer and a recirculating batch dryer were compared with conventional wagon drying systems. The rate of change of peanut kernel moisture content (% w.b./h) was considerably higher in the single pass continuous flow (2.1%/h) and the recirculating batch (1.0%/h) dryers than observed in conventionally cured peanuts (0.41%/h). Peanuts cured using the single–pass continuous flow dryer had unacceptably high levels of split and bald kernels when compared to those cured in wagons. The recirculating batch dryer resulted in significantly higher percent split kernels and skin slippage. However, the reduction in peanut milling quality may be acceptable in order to achieve the faster drying rate.

Mutagenicity and Identification of Mutagenic Compounds of Fumes Obtained from Heating Peanut Oil

Since the fume of cooking oil has been reported to increase the risk of lung cancer, the objectives of this study were to evaluate the mutagenicity and to find the mutagens in the fumes of peanut oil heated to the smoke point. Peanut oil prepared from roasted peanut kernel showed a lower smoke point, less unsaturated fatty acids, more fume formation, and stronger mutagenicity than that from unroasted kernel. Further investigation of mutagenic compounds was performed by the Ames test and gas chromatography/mass spectrometry analysis. Among the 12 compounds identified from the neutral fraction of methanol extract, four compounds at a dose of 10 μg per plate were mutagenic to Salmonella Typhimurium TA98 and TA100 in the order of trans-trans-2,4-decadienal >trans-trans-2,4-nonadienal >trans-2-decenal >trans-2-undecenal. Results report the enal compounds formed as the mutagens in the fumes of peanut oil and indicate that inhaling cooking fumes might cause carcinogenic risk.

Proportion of aflatoxin B1 contaminated kernels and its concentration in imported peanut samples

Moldy and split peanut kernels were separated from peanuts exported from Brazil, Sudan, India and Taiwan by visual inspection. The remaining peanuts from Brazil, Sudan and India were roasted lightly and the skins were removed. Stained peanuts were separated from the others. Aflatoxin was detected in moldy and stained peanuts. There was a positive correlation between % of aflatoxin-contaminated peanut kernels and aflatoxin B1 concentration in whole samples. Aflatoxin concentration of moldy peanuts was higher than that of stained peanut kernels.

Antioxidative activity of roasted and defatted peanut kernels

Peanut kernels were roasted at 180±2°C for various period of times (0–60 min); then grounded and defatted or further hydrolyzed with proteases to test their antioxidative activity (AOA). Samples roasted for 60 min displayed the most remarkable AOA, determined by Ferric-thiocyanate method, on linoleic acid in emulsions prepared with Tween 20 or 80. In reducing power, the absorbance at 700 nm of enzymatic hydrolysates (1 mg/ml) prepared from a 60-min-roasted sample with Esperase (enzyme/substrate=1/200, 60°C, pH 8.0) and with Neutrase (enzyme/substrate=1/200, 50°C, pH 6.0) was 1.24 and 0.81, respectively. The scavenging activity of Esperase and Neutrase hydrolysates on DPPH (α, α′- diphenyl-β-picryldrazyl) radicals was 93 and 89%, respectively, while their chelating activity on Fe +2 was 69 and 52%, respectively. Besides, in vitro, Esperase hydrolysates (⩾100 μg/ml) exhibited the remarkable antioxidative effect on the oxidation of low-density lipoprotein (LDL) induced by copper by showing a lag time of longer than 6 h.

Variation in Nitrogen-to-Protein Conversion Factor for Peanut

Abstract For peanut, a factor of 5.46 is used for converting nitrogen concentration into protein concentration because the peanut proteins arachin and conarachin contain 18.31% nitrogen. Using published reports on the amino acid composition of peanut genotypes, the nitrogen-to-protein conversion factors (NPCF) for arachin and conarachin, as well as for whole peanut kernel were calculated. The value of NPCF for arachin varied between 5.271 and 5.563 and that for conarachin from 5.076 to 5.496. The location of crop growth may significantly affect the value of NPCF for whole kernels. For the samples of various genotypes grown at various locations, the values of NPCF varied between 5.3 and 5.7. Thus, the protein content obtained by using the conventional factor of 5.46 would have a precision of ± 0.7% for samples having 3.5% N (approx. 18% protein). As the nitrogen content increases, the precision decreases to reach ± 1.1% for samples having 5.5% N (approx. 30% protein). This implies that the protein contents of peanut calculated on the basis of a fixed conversion factor would be significantly different only when they differ by 1.4 to 2.2% in the calculated values. Therefore, use of a fixed NPCF for comparison of concentration of protein in samples emanating from breeding or agronomic trials may be erroneous, especially when samples differ only marginally in their protein concentrations. Research will be required to determine the relationship between the nitrogen concentration of peanut kernel samples and their protein concentration.

POD YIELD AND KERNEL SIZE DISTRIBUTION OF PEANUT PRODUCED USING SUBSURFACE DRIP IRRIGATION

Longterm yield data are essential to determine the economic feasibility of installing a subsurface drip irrigation(SDI) system for crop production. However, first year yields and associated economic returns are vital for system paymentthe first year. Vegetable and row crop production has been successful with SDI, but pod yield and kernel size distribution dataon peanut (Arachis hypogaea L.) are limited especially during the installation year. Site 1 was established in 1997 on aFaceville sandy loam soil (fine, kaolinitic, thermic Typic Kandiudults) converted from native grass pasture. Site 2 wasestablished in 1998 on a Tifton sandy loam soil (fineloamy, kaolinitic, thermic Plinthic Kandiudults) following two yearsof cotton. These SDI systems include two lateral spacings (0.91 and 1.83 m) buried at 0.3 m soil depth. Site 1 had two emitterspacings (46 and 61 cm) and two irrigation levels. Site 2 had one emitter spacing (46 cm) and three irrigation levels. Anonirrigated (NI) control was included at each site. Irrigation water was applied daily based on estimated ETo whereirrigation level one (IL1) was ETo *Kc, and IL2 and IL3 were 75 and 50% of IL1, respectively. Pod yield increased 38% withSDI (5433 kg ha 1 ) compared to NI peanut (3937 kg ha 1 ). When compared to the state average (3012 kg ha 1 ), SDI showeda 81% pod yield increase. The percentage of jumbo kernels increased 39% at Site 1 and 81% at Site 2 compared with NI. SDIpeanut had lower quantity (75% less) of number one sized peanut kernels than NI. Overall, during the installation year, SDIhad higher pod yields and larger kernel size than NI treatments. These yield data can be useful when projecting the economicfeasibility of installing a SDI system and making the first year payment.

NON–DESTRUCTIVE DETECTION OF PEANUT OFF–FLAVORS USING AN ELECTRONIC NOSE

An electronic nose was tested to determine if half–kernel, whole kernel, and pod peanuts could be significantly separated based on the presence of off–flavor–indicating volatiles in the kernel. The sampling and data analysis technique used was developed previously and successful at separating ground peanut kernels. Statistically significant differences were detected for all three levels of sample destruction. The electronic nose was able to separate pods at a higher level of significance than the OVM technique and the GC technique for ethanol and ethyl acetate.

Deterioration and spoilage of peanuts and desiccated coconuts from two sub-Saharan tropical East African countries due to the associated mycobiota and their degradative enzymes.

A broad variety of fungi (84 species belonging to 36 genera) were identified with more taxa infesting peanut seed samples from two tropical countries (29 genera and 61 species) compared to those found in desiccated coconuts (20 genera and 55 species) on both DRBC and DG18 media. This may be due to the higher moisture levels in peanuts (5.07-7.97%) compared with coconuts (1.5-4.17%). More taxa and propagules were recovered on DG18 in both cases. The dominant fungi from both substrates on both isolation media were Aspergillus and Penicillium, with other fungi from only one substrate/medium. The aflatoxigenic species (A. flavus) dominated Kenyan samples more so than Ugandan samples on both substrates. However only 71.5% and 87.5% of the peanut kernels, on DRBC and DG18, respectively, were found to be infested with fungi. The aflatoxigenic species (A. flavus/parasiticus) were found in 75% of the samples, however only 15.75% and 13% of the kernels analyzed were infested. The most frequently isolated species from peanuts were A. niger followed by A. flavus and M. phaseolina. E. repens, E. amstelodami, E. rubrum and E. chevalieri dominated peanut seeds on DG18, and R. stolonifer, A. parasiticus, F. solani, L. theobromae and P. chrysogenum on DRBC. The mean count of fungal propagules in coconut samples were approximately 0.7 x 10(3) and 0.8 x 10(3) on DRBC and DG18, respectively, with a high proportion of those propagules recorded for the aflatoxigenic species (about 0. 17 x 10(3) and 0.25 x 10(3) colonies/g). The mycobiota of desiccated coconut was dominated by A. niger, A. flavus and P. chrysogenum. Also A. ochraceus, P. waksmanii, Paecilomyces variotii, P. islandicum and R. mucilaginosa were more frequent on DRBC, while, species of Cladosporium. Chrysosporium and Eurotium were more frequent on DG18. Enzyme indices (or the activities) for each specific strain, when determined after 5 and 8 days of incubation, proved to be similar. A recommendation is given. The proteolytic and lipolytic potentialities of the most commonly encountered species from both peanuts and coconuts were studied. The most interesting observation is that most of the positive isolates, in both commodities had high enzymic activity compared to those reported earlier for isolates of the same species. Such capabilities suggest that these commodities are expected to deteriorate, since climatic conditions in tropical areas favour fungal proliferation. Emphasis on the proper harvesting, drying, handling, transportation and/or storage; and also education of the populace, especially those are dealing with these foods, should be taken into consideration by the relevant authorities. The contaminated foods constitute a health hazard for human consumption.

A Rapid Method to determine the Sorption Isotherms of Peanuts

A rapid method has been developed to determine the sorption isotherms of peanuts. The equilibrium relative humidities ranging from 10 to 95% for peanut pods, kernels and hulls were measured at temperatures ranging from 5 to 45°C. No significant differences were found between the experimental results of the equilibrium moisture content and equilibrium relative humidity methods. The curve-fitting agreement of the adsorption and desorption data for four equilibrium relative humidity models was evaluated. The best models and their estimated parameters were shown in this study.