"Exploring Locally Sourced Cereal Grains As Alternative Media For Fungal Growth: A Comparative Study With Potato Dextrose Agar"

A total of 10 species of fungi belonging to 5 genera were isolated and identified from four cereal grains; wheat, barley, rice and maize collected from three Libyan cities known to grain producers (Al-Zawia, Subratah and Tripoli) on 1% dextrose-Czapkes agar medium at 28 ± 2°C for 7-15 days using seed-plate method. Two species of Alternaria ( A. raphani and A. tenusinae ); two species of Aspergillus ( A. flavus and A. niger ); three Fusarium ( F. graminearum, F. moniliforme and F. solani ); one Rhizopus species ( Rhizopus stolonifer ) and two species of Penicillium ( P. digitatum and P. notatum ) were isolated from the grains. The densities of these fungi and their frequencies of occurrence have been investigated. It can be concluded that for human public health, cereal grains of production chain must be subjected to quality control and microbiological examinations.

Traditional African cereal grains, acha (Digitaria exilis Stapf), iburu (Digitaria iburuaStapf) and tamba (Eluesine coracana) though poorly studied have received an increasing attention by scientists within the last decade as revealed from the literature. They have potential to contribute significantly to whole grain diets, wellness, economic status improvement, and play important role in food security in developing economy. They are considered as health grains in the sense that they are often consumed whole and are gluten-free. Studies have shown that sprouting and fermenting tamba (finger millet) with fungus adds value for effective utilization and provides scope for development of functional food. Like other emerging ancient grains, these cereals with excellent culinary and nutritional properties have potential in new product development as they are believed to represent the highest quality of vitamins, minerals, fibre and the sulphur containing amino acids. Food industry may look into their use as ingredients in product formulation considering growing awareness of a healthy diet and challenging cost of health care. Value addition and exploitation of these cereal grains require concerted and collaborative efforts in terms of infrastructure, funding, innovation, purposeful policies from governments, international donors, academia, food industry, the private sector if the growing population in the sub-Saharan region is to experience the full benefits of cereal grains for active and healthy life; hence this review. Key words: Cereal, wholegrain, Digitaria spp., acha, iburu, Eluesine spp., tamba, raji, finger millet.

The ruminal fungi Orpinomyces joyonii strain 19-2, Neocallimastix patriciarum strain 27, and Piromyces communis strain 22 were examined for their ability to digest cereal starch. All strains digested corn starch more readily than barley or wheat starch. Orpinomyces joyonii 19-2 exhibited the greatest propensity to digest starch in wheat and barley, whereas the digestion of these starches by N. patriciarum 27 and P. communis 22 was limited. Media ammonia concentrations were lower when fungal growth was evident, suggesting that all strains assimilate ammonia. Fungi formed extensive rhizoidal systems on the endosperm of corn, but O. joyonii 19-2 was the only strain to form such systems on the endosperm of wheat and barley. All strains penetrated the protein matrix of corn but did not penetrate starch granules. Starch granules from all three cereals were pitted, evidence of extensive digestion by extracellular amylases produced by O. joyonii 19-2. Similar pitting was observed on the surface of corn starch granules digested by N. patriciarum 27 and P. communis 22, but not on wheat and barley starch granules. The ability of ruminal fungi to digest cereal grains depends on both the strain of fungus and the type of grain. The extent to which fungi digest cereal grain in the rumen remains to be determined.

Fungi are distributed worldwide and can be found in various foods and feedstuffs from almost every part of the world. Mycotoxins are secondary metabolites produced by some fungal species and may impose food safety risks to human health. Among all mycotoxins, aflatoxins (AFs), ochratoxin A (OTA), trichothecenes, deoxynivalenol (DON and T-2 toxin), zearalenone (ZEN), and fumonisins (FMN) have received much attention due to high frequency and severe health effects in humans and animals. Malaysia has heavy rainfall throughout the year, high temperatures (28 to 31 °C), and high relative humidity (70% to 80% during wet seasons). Stored crops under such conditions can easily be contaminated by mycotoxin-producing fungi. The most important mycotoxins in Malaysian foods are AFs, OTA, DON, ZEN, and FMN that can be found in peanuts, cereal grains, cocoa beans, and spices. AFs have been reported to occur in several cereal grains, feeds, nuts, and nut products consumed in Malaysia. Spices, oilseeds, milk, eggs, and herbal medicines have been reported to be contaminated with AFs (lower than the Malaysian acceptable level of 35 ng/g for total AFs). OTA, a possible human carcinogen, was reported in cereal grains, nuts, and spices in Malaysian market. ZEN was detected in Malaysian rice, oat, barley, maize meal, and wheat at different levels. DON contamination, although at low levels, was reported in rice, maize, barley, oat, wheat, and wheat-based products in Malaysia. FMN was reported in feed and some cereal grains consumed in Malaysia. Since some food commodities are more susceptible than others to fungal growth and mycotoxin contamination, more stringent prevention and control methods are required.

Food and nutrition insecurity are inability to access adequate amount of nutritious foods to meet dietary needs for a productive and healthy life. However, food and nutrition insecurity, in some part of Ethiopia, is very high though food is not scarce. Therefore, a survey was conducted to investigate food consumption and dietary habits of the population in the district. A questionnaire and focus group discussions were used for data collection. Data were collected on available food sources and habits of consumption in purposively selected four kebeles in the district. Data were specifically collected on utilization and eating habit of cereal grains, legumes, fruit, vegetables, and animal food sources. A total of 150 representative sample households were interviewed based on the population size of the study area. The result obtained from the survey indicated that cereal grains (34.9%), legumes & pulses (28.5%), fruit & vegetables (16.8%), meat and poultry (19.8%) products are commonly produced in many parts of the study area. The study indicated that the population entirely consumes cereal grains that are mainly sources of carbohydrate, with minimal consumption of other food types. Though there are surplus food items in the study area, there is poor utilization and undiversified consumption habit. This indicates that the area is vulnerable for food and nutrition insecurity. Therefore, knowledge on proper utilization of local existing food sources for enhancing food and nutrition security is essential. Awareness creation on benefits and preparation of balanced diet at household level from local food sources is a vital to improve food and nutrition security in the study area.

Mitigating fungal contamination of cereals: The efficacy of microplasma-based far-UVC lamps against Aspergillus flavus and Fusarium graminearum

PurposeThe aim of this paper is to evaluate the storage stability of improved dambu, a steamed granulated dumpling product generally made from millet, was produced from maize (Zea mays), millet (Pennisetum glaucum), sorghum (Sorghum bicolor) and acha (Digitaria exilis). It is a popular mid‐day meal of the Fulanis of Nigeria normally sprinkled into fermented skimmed milk or whole milk and sugar may be added to taste.Design/methodology/approachImproved dambu was prepared in the laboratory using decorticated clean cereal grains which were pulverished into coarse particles, mixed with spices, preservative (sorbic acid) and water and steamed for 20 min. The improved dambu products were packaged in low‐density polyethylene (LDPE), LDPE with plastic and LDPE with paperboard and stored at room temperature (25 ○C) for six days. Analysis was carried out on the products following documented and established procedures.FindingsData obtained indicated that during storage, pH decrease was observed while titratable acidity increased for improved dambu products. The microbial load (cfu/g) increased with storage time for all the products packaged in LDPE, LDPE with plastic and LDPE with paperboard. Dambu has a limited storage life of one day at room temperature (25 ○C) and four days with 0.2 per cent (w/w) sorbic acid as preservative. Micro‐organisms of significance in the products are Aspergillus sp, Penicillum sp, Candida sp, Staphylococcus aureus and Enterobacter aerogenes. The nature of the microflora suggested that dambu is a good substrate for fungal growth. In the comparative study of dambu products with and without sorbic acid, there was no significant difference in the mean scores for all the assessed parameters.Research limitations/implicationsThe consumption of dambu from different cereal grains is encouraged especially where a particular cereal is off season. The shelf‐life of dambu was extended to four days by using 0.2 per cent (w/w) sorbic acid as preservative and packaged in LDPE with plastic and LDPE with paperboard. Further research should be carried out to extend the shelf‐life more.Practical implicationsThe findings have suggested that dambu is necessary to cereal industry and baby foods (weaning foods).Originality/valueThe results of this research contributes to the knowledge of cereal meals, especially those that are indigenous to Nigeria and West Africa.

Integrated management of the risks of stored grain spoilage by seedborne fungi and contamination by storage mould mycotoxins – An update

Deoxynivalenol (DON), a mycotoxin primarily produced by Fusarium species, is commonly found in cereal grains and poses risks to human and animal health, as well as global grain trade. This study demonstrates that methyl jasmonate (MeJA), a natural plant hormone, inhibits the growth and conidiation of Fusarium graminearum. Importantly, MeJA significantly reduces DON production by suppressing TRI gene expression and toxisome formation. To explore the molecular mechanism, we identified MeJA-tolerant mutants, including a transcription factor MRT1 and cAMP-PKA pathway-related genes (FgGPA1 and FgSNT1). MeJA treatment reduced PKA activity and intracellular cAMP levels in F. graminearum, suggesting it targets the cAMP-PKA pathway. Notably, the MeJA-resistant mutant FgGPA1R178H enhanced fungal growth, DON production, and cAMP levels in the presence of MeJA. Exogenous cAMP alleviated MeJA's inhibitory effects on DON production, further supporting this pathway's involvement. Interestingly, MeJA had no effect on all three MAP kinase pathways (Mgv1, Gpmk1, and FgHog1). Truncated and phospho-mimicking mutations in Mrt1 or FgSnt1 conferred MeJA resistance, suggesting they may act downstream of the cAMP-PKA pathway. In conclusion, MeJA presents a promising approach to control F. graminearum growth and DON production.IMPORTANCEDeoxynivalenol (DON) poses significant risks to both human and animal health and severely disrupts the global grain trade due to its prevalence as a common contaminant in wheat grains. With rising public concern over food safety, finding effective and sustainable methods to reduce DON contamination becomes increasingly urgent. In our study, we found that methyl jasmonate (MeJA), a natural plant hormone, can effectively inhibit the vegetative growth of F. graminearum and significantly reduce its DON toxin production. To explore the underlying molecular mechanism, we identified the mutations in MeJA-tolerant mutants and revealed that MeJA effectively exerts its antifungal activities by inhibiting the cAMP-PKA signaling pathway in F. graminearum. Our work provides a promising natural solution to reduce DON toxin contamination in cereal grains, enhancing food safety while decreasing the reliance on chemical fungicides and their associated environmental impact.

Mycotoxins are toxic metabolites produced by certain types of fungi, causing pathological changes in humans and animals. The aim of this study was to assess the degree of contamination of selected cereal grains, bran and cereal products intended for children, with mycotoxins using GCxGC-TOF-MS technique. The study involved mycotoxins belonging to the type A and B trichothecenes group, including T-2 toxin (T-2), HT-2 toxin (HT-2), scirpenol (SCI), 15-monoacetoxyscirpenol (15-MAS), diacetoxyscirpenol (DAS), triacetoxyscirpenol (TAS), fusarenon-X (FUS-X), nivalenol (NIV), deoxynivalenol (DON), 3-acetyl-DON (3-Ac-DON), 15-acetyl-DON (15-Ac-DON). The study also assessed the effect of conditions in which the samples were stored, including temperature (6°C and 28°C) and time (14 and 28 days), on fungal growth and mycotoxin production. Among all studied compounds, only DAS and HT-2 toxins were detected in tested samples, with the exception of products intended for children. Measured HT-2 mycotoxin content in tested samples was in the range 83.9 - 196.4µg kg -1. Experiments with storage conditions showed a statistically significant increase in the HT-2 toxin level after 14 days of storage in all samples, irrespective of temperature. Prolonged storage (additional 14 days) did not cause significant changes in the HT-2 content. Further analyses showed a statistically significant effect of storage temperature on HT-2 toxin levels only in cereal products intended for children after both 14 and 28 days. Interestingly, lower temperature (6°C) was more optimal then higher temperature (28°C) for the HT-2 toxin production. No significant effect of storage temperature on HT-2 level was observed for cereal grains and bran.

Chitinolytic bacteria are used as biocontrol agents of plant pathogenic fungi. They might also potentially inhibit growth of molds, e.g., Aspergillus spp. and Penicillium spp., in stored plant material. We isolated chitinolytic bacteria from airtight stored cereal grain and evaluated their antifungal capacity. Between 0.01 and 0.5% of the total aerobic counts were chitinolytic bacteria. Gram-negative bacteria, mainly Pseudomonadaceae, constituted approximately 80% of the chitinolytic population. Gram-positive isolates belonged predominantly to the Corynebacterium-Arthrobacter group, Streptomyces, and Bacillus. Chitinolytic activity was evaluated using culture filtrates from chitin-grown isolates as the release of p-nitrophenol from p-nitrophenyl N,N'-diacetylchitobiose and as the formation of clearing zones on chitin agar. No correlation between chitinolytic activity and antifungal effects was found when challenging Penicillium roqueforti Dierckx with bacterial isolates on chitin agar in a dual culture bioassay. Fungal hyphae frequently grew seemingly unaffected through the bacterial colony of a high chitinase producer on colloidal chitin. Only 4% of the chitinolytic isolates had strong effects on fungal growth. Among these, Streptomyces halstedii (K122) and Streptomyces coelicolor (K139) inhibited growth of a broad range of fungi. Streptomyces halstedii affected hyphal morphology and decreased the radial growth rate of all fungi investigated. These effects were not caused by volatile metabolites, polyenes, or N-carbamoyl-D-glucosamine.Key words: antifungal, chitinase, Streptomyces halstedii, Streptomyces coelicolor.

Detection of fungal contamination of cereal grain samples by an electronic nose

Cereal grains are the most important food source for humans. As the global population continues to grow exponentially, the need for the enhanced yield and minimal loss of agricultural crops, mainly cereal grains, is increasing. In general, harvested grains are stored for specific time periods to guarantee their continuous supply throughout the year. During storage, economic losses due to reduction in quality and quantity of grains can become very significant. Grain loss is usually the result of its deterioration due to fungal contamination that can occur from preharvest to postharvest stages. The deleterious fungi can be classified based on predominance at different stages of crop growth and harvest that are affected by environmental factors such as water activity (aw) and eco-physiological requirements. These fungi include species such as those belonging to the genera Aspergillus and Penicillium that can produce mycotoxins harmful to animals and humans. The grain type and condition, environment, and biological factors can also influence the occurrence and predominance of mycotoxigenic fungi in stored grains. The main environmental factors influencing grain fungi and mycotoxins are temperature and aw. This review discusses the effects of temperature and aw on fungal growth and mycotoxin production in stored grains. The focus is on the occurrence and optimum and minimum growth requirements for grain fungi and mycotoxin production. The environmental influence on aflatoxin production and hypothesized mechanisms of its molecular suppression in response to environmental changes are also discussed. In addition, the use of controlled or modified atmosphere as an environmentally safe alternative to harmful agricultural chemicals is discussed and recommended future research issues are highlighted.

Mycotoxins contaminating cereal grain crops: Their occurrence and toxicity

Nutrition-rich cereal grains and oil seeds are the major sources of food and feed for human and livestock, respectively. Infected by fungi and contaminated with mycotoxins are serious problems worldwide for cereals and oil seeds before and after harvest. The growth and development activities of fungi consume seed nutrients and destroy seed structures, leading to dramatic declines of crop yield and quality. In addition, the toxic secondary metabolites produced by these fungi pose a well-known threat to both human and animals. The existence of fungi and mycotoxins has been a redoubtable problem worldwide for decades but tends to be a severe food safety issue in developing countries and regions, such as China and Africa. Detection of fungal infection at an early stage and of mycotoxin contaminants, even at a small amount, is of great significance to prevent harmful toxins from entering the food supply chains worldwide. This review focuses on the recent advancements in utilising infrared spectroscopy, Raman spectroscopy, and hyperspectral imaging to detect fungal infections and mycotoxin contaminants in cereals and oil seeds worldwide, with an emphasis on recent progress in China. Brief introduction of principles, and corresponding shortcomings, as well as latest advances of each technique, are also being presented herein.