Change in Water Activity and Fungal Counts of Maize-pigeon Pea Flour During Storage Utilizing Various Packaging Materials

AbstractMaize-pigeon pea fortified flour has been processed with the potential to address protein-malnutrition, especially among children. This combination is preferred since cereals lack amino acids, such as methionine, and legumes lack lysine. When mixed together, the amino acid concentrations can be complemented. However, stored maize is an excellent substrate for Aspergillus spp., especially under warm (20-300C) and humid conditions (70-900C). This study investigated the changes in water activity and fungal counts in maize-pigeon pea flour stored for up to 8 weeks using different packaging materials. Maize pigeon flour was processed at different concentrations of 90:10 to 70:30 from fermented, dried, and milled maize and blanched, dehulled, and milled pigeon pea seeds. The flour samples were packaged into four different packaging materials: low and high density polythene bags, as well as plastic and aluminum containers. These containers were stored under simulated tropical conditions of 28+20C and 83+2% relative humidity in an incubator. Water activity (aw) of the flours was determined and fungi were enumerated using Petrifilm. Initial (day 0) aw of samples ranged from 0.15 to 0.17; after 8 weeks, aw ranged from 0.20 to 0.32 in low density polyethene, while lower aw was recorded for samples stored in the plastic and aluminum containers. Initial fungal counts ranged from 1.69 to 2.31 log10 CFU/g which increased from a range of 2.45 to 2.78 log10 CFU/g after 8 weeks of storage, with higher counts in samples stored in low density polythene bags. These results indicate that aw and fungal counts of the flours increased slightly over time in the different packaging materials, but values appear to be within tolerable limits. Further research will evaluate the stability of amino acids, as well as the level of fungi and resulting aflatoxin production up to 11 months under the storage conditions, formulations, and packaging materials described above

Aflatoxin Contamination in Food and Body Fluids in Relation to Malnutrition and Cancer Status in Cameroon

Aflatoxins are food contaminants usually associated with hepatitis, immunodepression, impairment of fertility and cancer. The present work was to determine the presence of aflatoxins in eggs, milk, urine, and blood samples that were collected from various sources and periods; and hepatitis B virus antigen in blood samples. Aflatoxin was found in eggs (45.2%), cow raw milk (15.9%), breast milk (4.8%), urine from kwashiorkor and marasmic kwashiorkor children (45.5%), and sera from primary liver cancer patients (63.9%); HbsAg was also detected in 69.4% of the serum samples, but there was no association between both factors. Both AF and hepatitis B virus seem to be risk factors that could increase the incidence and prevalence rates of malnutrition and cancer in Cameroon

Interakcije nekih plijesni i aflatoksinogenog soja Asspergillus flavus NRRL 3251

The objective of this study was to evaluate biotic interaction between some mould species and active producer of aflatoxin B1 Aspergillus flavus NRRL 3251, co-cultured in yeast-extract sucrose (YES) broth. Twenty-five mould strains of Alternaria spp., Cladosporium spp., Mucor spp., A. flavus and A. niger, used as biocompetitive agents, were isolated from outdoor and indoor airborne fungi, scrapings of mouldy household walls, and from stored and post-harvest maize. Aflatoxin B1 was extracted from mould biomasses with chloroform and detected using the multitoxin TLC method. The results confirm antagonistic interaction between all strains tested. With Alternaria spp. and Cladosporium spp., aflatoxin B1 production decreased 100 %, compared to detection in a single culture of A. flavus NRRL 3251 (Cmean=18.7 µg mL-1). In mixed cultures with Mucor spp., aflatoxin B1 levels dropped to (5.6-9.3) µg mL-1, and the inhibition was from 50 % to 70 %. Four of five aflatoxin non-producing strains of A. flavus interfered with aflatoxin production in mixed culture, and reduced AFB1 productivity by 100 %. One strain showed a lower efficacy in inhibiting AFB1 production (80 %) with a detectable amount of AFB1 3.7 µg mL-1 when compared to control. A decrease in toxin production was also observed in dual cultivation with A. niger strains. It resulted in 100 % reduction in three strains), 90 % reduction in one strain (Cmean=1.9 µg mL-1) and 80 % reduction in one strain (Cmean=3.7 µg mL-1) inhibition.Cilj rada bio je procijeniti biotske interakcije između sojeva različitih vrsta plijesni i kontrolnog soja Aspergillus flavus NRRL 3251, producenta aflatoksina B1 (AFB1). Inhibitorno djelovanje u miješanim kulturama na tvorbu AFB1 ispitano je na dvadeset pet sojeva Alternaria, Cladosporium, Mucor i Aspergillus vrsta izoliranih iz zraka, strugotina pljesnivih zidova te uskladištenog i prezimljenog kukuruza. Biosinteze su provedene u tekućoj hranjivoj podlozi s kvaščevim ekstraktom (YESbujon). Ekstrakcije AFB1 iz biomase izvršene su multitoksinskom metodom tankoslojne kromatografije. Rezultati biotskih interakcija pokazali su antagonistički odnos svih testiranih sojeva. Alternaria i Cladosporium vrste simultano inokulirane sporama A. flavus NRRL 3251 inhibirale su tvorbu AFB1 100 % u odnosu na dokazani toksin u kontrolnoj biosintezi (konc. 18,7 µg mL-1). U miješanim kulturama vrstama roda Mucor dokazane su padajuće koncentracije AFB1 (9,3 µg mL-1, 7,5 µg mL-1 i 5,6 µg mL-1), odnosno inhibicija tvorbe toksina 50 % do 70 %. Atoksinogeni sojevi A. flavus inhibirali su tvorbu AFB1 80 % (1 soj, konc. 3,7 µg mL-1) i 100 % (4 soja). Antagonističko djelovanje prema toksinogenom soju, smanjujući tvorbu AFB1 u rasponu 80 % do 100 % (konc. 1,9 µg mL-1 i 3,7 µg mL-1), dokazano je u uzgojnim biosintezama s A. niger

Predicted Roles of the Uncharacterized Clustered Genes in Aflatoxin Biosynthesis

Biosynthesis of the toxic and carcinogenic aflatoxins (AFs) requires the activity of more than 27 enzymes. The roles in biosynthesis of newly described enzymes are discussed in this review. We suggest that HypC catalyzes the oxidation of norsolorinic acid anthrone; AvfA (AflI), the ring-closure step in formation of hydroxyversicolorone; HypB, the second oxidation step in conversion of O-methylsterigmatocystin to AF; and HypE and NorA (AflE), the final two steps in AFB1 formation. HypD, an integral membrane protein, affects fungal development and lowers AF production while AflJ (AflS), has a partial methyltransferase domain that may be important in its function as a transcriptional co-activator

Edible films and coatings as carriers of living microorganisms: a new strategy towards biopreservation and healthier foods

Edible films and coatings have been extensively studied in recent years due to their unique properties and advantages over more traditional conservation techniques. Edible films and coatings improve shelf life and food quality, by providing a protective barrier against physical and mechanical damage, and by creating a controlled atmosphere and acting as a semipermeable barrier for gases, vapor, and water. Edible films and coatings are produced using naturally derived materials, such as polysaccharides, proteins, and lipids, or a mixture of these materials. These films and coatings also offer the possibility of incorporating different functional ingredients such as nutraceuticals, antioxidants, antimicrobials, flavoring, and coloring agents. Films and coatings are also able to incorporate living microorganisms. In the last decade, several works reported the incorporation of bacteria to confer probiotic or antimicrobial properties to these films and coatings. The incorporation of probiotic bacteria in films and coatings allows them to reach the consumers gut in adequate amounts to confer health benefits to the host, thus creating an added value to the food product. Also, other microorganisms, either bacteria or yeast, can be incorporated into edible films in a biocontrol approach to extend the shelf life of food products. The incorporation of yeasts in films and coatings has been suggested primarily for the control of the postharvest disease. This work provides a comprehensive review of the use of edible films and coatings for the incorporation of living microorganisms, aiming at the biopreservation and probiotic ability of food products.Ana Guimaraes received support through grant SFRH/BD/ 103245/2014 from the Portuguese Foundation for Science and Technology (FCT). Luís Abrunhosa was supported by grant UMINHO/BPD/51/2015 from project UID/BIO/04469/2013 financed by FCT/MEC (OE). This study was supported by FCT under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684), and of BioTecNorte operation (NORTE-01-0145-FEDER000004) funded by European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. Vectors used in Figure were designed by Freepik.info:eu-repo/semantics/publishedVersio

Growth and aflatoxin production of Aspergillus flavus in the presence of Lactobacillus species

A commercial silage inoculant mixture of Lactobacillus species inhibited aflatoxin production by Aspergillus flavus subsp parasiticus. Germination of mold spores was inhibited by actively growing Lactobacillus cells, however Lactobacillus cell free supernatant did not affect mold spore viability. Aflatoxin production was inhibited in Lablemco Tryptone Broth (LTB) by Lactobacillus species growing inside dialysis sacks (molecular weight cutoffs of 1000, 6-8000 and 12-14,000) immersed in the LTB. Aflatoxin levels were also significantly reduced when Lactobacillus species were inoculated into a growing mold culture, and also when mold spores were injected into Lactobacillus cultures. Different Lactobacillus isolates were purified from the silage inoculant mixture. Some of the isolates had no effect on mold growth and aflatoxin production. Other Lactobacillus isolates showed various degrees of aflatoxin inhibition. Lactobacillus isolate 371, which was identified as Lactobacillus casei pseudoplantarum, was found to greatly inhibit the production of aflatoxins B1 and G1. The inhibition of aflatoxins by Lactobacillus casei pseudoplantarum 371 was not eliminated by replacing an amount of glucose equal to the amount used by Lactobacillus sp before inoculation of the mold. The inhibitory principle in a Lactobacillus cell free supernatant was found to be sensitive to trypsin and $\alpha$-chymotrypsin, but not to pepsin. Dialyzed protein concentrate of the Lactobacillus cell free supernatant greatly inhibited aflatoxin formation. The antiaflatoxigenic activity of the supernatant was destroyed at 100 C within 10 mn. While Lactobacillus casei pseudoplantarum 371 inhibited aflatoxin production in broth, it did not have any effect on mold growth and aflatoxin production in sterile steamed rice, when mold growth was monitored by ergosterol and plate count techniques. Ergosterol determination was found to be a sensitive indicator of low levels of fungal activity and aflatoxin production in rice. Ergosterol formation in rice followed the same trend as aflatoxin B1 production. The inhibitory activity of the Lactobacillus isolate was shown to inactivate the enzymatic system required for the production of aflatoxin B1