ABSTRACT
Crop contamination with mycotoxins is a global problem with a negative impact on human and animal health as well as causing economical losses in food and feed chains. This study was focused on the evaluation of the effect of lactic acid bacteria (LAB) strain (Levilactobacillus brevis-LUHS173, Liquorilactobacillus uvarum-LUHS245, Lactiplantibacillus plantarum-LUHS135, Lacticaseibacillus paracasei-LUHS244 and Lacticaseibacillus casei-LUHS210) fermentation on the changes in the level of deoxynivalenol (DON) and its conjugates in Fusarium spp.-contaminated barley wholemeal (BWP). Samples, with different contamination of DON and its conjugates, were treated separately (for 48 h). In addition to mycotoxin content, enzymatic activities (amylolytic, xylanolytic, and proteolytic) of BWP (before and after fermentation) were evaluated. It was established that the effect of decontamination depends on the LAB strain used, and a significant reduction in DON and the concentration of its conjugates in Lc. casei fermented samples was achieved: the amount of DON decreased on average by 47%, and the amount of D3G, 15-ADON and 3-ADON decreased by 82.4, 46.1, and 55.0%, respectively. Lc. casei also showed viability in the contaminated fermentation medium and an effective production of organic acids was obtained. Additionally, it was found that enzymes are involved to the detoxification mechanism of DON and its conjugates in BWP. These findings indicate that fermentation with selected LAB strains could be applied for contaminated barley treatment in order to significantly reduce Fusarium spp. mycotoxin levels in BWP and improve the sustainability of grain production.
ABSTRACT
This study was dedicated to increasing the efficiency of producing plant-based protein hydrolysate using traditional and non-traditional treatments. Low- and high frequency ultrasound (US) at different intensities were applied to corn steep liquor (CSL) at 50 °C for 30 min, and enzymatic hydrolysis was performed using industrially produced alkaline protease. The efficiency of US and enzymatic treatments was characterized by protein solubility (soluble protein (SP) content, hydrolyzed protein (HP) concentration, and free amino acid (FAA) profile) and kinetic parameters: Michaelis-Menten constant (KM) and apparent breakdown rate constant (kA). A significant effect of 37 kHz US pre-treatment for CSL enzymatic hydrolysis was found and resulted in the highest HP concentration (17.5 g/L) using the lowest enzyme concentration (2.1 g/L) and the shortest hydrolysis time (60 min). By using US pre-treatment, on average, a 2.2 times higher FAA content could be achieved compared to traditional hydrolysis. Additionally, results for the kinetic parameters kM and kA confirmed the potential of applying US treatment before hydrolysis. The effect of CSL protein hydrolysate on plant growth was tested in vivo on wheat grain seed germination and resulted in the significant increase in germination parameters compared to the control treatment. These findings indicate that by-products of starch industry could be a promising source for the production of low-cost sustainable biostimulants.
ABSTRACT
Aspergillus spp. are widely occurring fungi in nature; they produce toxic compounds such as aflatoxins (AFs) and mainly target plant products such as corn and nuts. The development of prevention strategies is challenging because AFs are highly toxic and have been regulated to small concentrations. This study proposes a new strategy of AF prevention through the application of rapid methods using acoustic techniques in combination with fermentation for the elimination of contaminated corn from bioethanol production processes. An acoustic device was used for the analysis of model systems consisting of corn and nuts (hazelnuts and peanuts) contaminated with different amounts of AFs. High correlations were obtained between penetrated acoustic signal amplitude (Ap) and corn sample density, and between Ap and AF content. Also, relationships were found between changes in Ap values and AF contamination in the nuts model systems. The results of biotreatment of contaminated corn during bioethanol production confirmed that AFs cannot be completely eliminated in dried distiller's grains with solubles, a valuable by-product for animal feed. Microbially, contamination of the raw material has a negative impact on bioethanol quality by increasing the content of volatile compounds. Therefore, the application of methods such as acoustic screening is a promising alternative for rapid AF detection in corn and nuts (it can handle multi-layers of grain). With the application of acoustic techniques, the prevention of AFs in contaminated raw plant materials could be achieved.
