Improved Microbial Quality of Buckwheat using Antimicrobial Solutions in a Fluidized Bed

Abstract

Buckwheat (Fagopyrum esculentum, Moench) is a specialty crop of interest because of its numerous nutritional, health, and agronomic benefits. A high microbial load on the seed often limits its export and use in functional foods; therefore, these generally recognized as safe antimicrobial treatments were evaluated for buckwheat disinfection: ozone gas, ozonated water, acetic acid (AA), acidic calcium sulfate (ACS), and combinations thereof. The liquid treatments were sprayed on buckwheat grain in a fluidized bed and the treated buckwheat was analyzed for aerobic plate count (APC) and yeast and mold count (YMC). Ozone gas and ozonated water treatments were not significantly (P < 0.05) effective in reducing the microbial load, and AA + ozonated water had significant but low effectiveness. Electron microscopic imaging suggested that rough surfaces and crevices in the seed hull shielded microbes from ozone treatments. Effectiveness of treatments was also limited by the industry limits on the amount of moisture that can be added to buckwheat grain. The ACS (50 mL/L) treatment was most effective with 3.9-log10 reduction in APC and complete elimination of YMC. ACS (50 mL/L) caused bleaching and increased redness. Sufficient reduction of microbes could be achieved at a lower concentration of ACS, thereby reducing the effect on color.

Simultaneous profiling of seed‐associated bacteria and fungi reveals antagonistic interactions between microorganisms within a shared epiphytic microbiome on Triticum and Brassica seeds

“…For some related crops, such as buckwheat, customers may set limits on total aerobic plate counts that are considerably lower (e.g. 5.5 log 10 CFU g −1 seeds) than we observed for Triticum and Brassica (Dhillon et al ., ), and lower total microbial loads are generally seen as desirable (Olaimat & Holley, ). The molecular methods used to estimate bacterial genomes g −1 seeds are unable to distinguish between viable and nonviable microbes, so estimates of total bacterial load by aerobic plate counts may be considerably lower than is determined using molecular methods.…”

Effect of saline organic acid solutions applied during soft wheat tempering on microbial load and flour functionality

“…Early investigations on this topic included the application of antimicrobial agents such as chlorine and ozone by means of washing, soaking, and fluidization systems (Dhillon, Wiesenborn, Sidhu, & Wolf-Hall, 2012;Dhillon, Wiesenborn, Wolf-Hall, & Manthey, 2009;İbanoǧlu, 2001); however, these methods resulted in the addition of more moisture to the grain than required for milling, thus introducing the need for a drying step. Early investigations on this topic included the application of antimicrobial agents such as chlorine and ozone by means of washing, soaking, and fluidization systems (Dhillon, Wiesenborn, Sidhu, & Wolf-Hall, 2012;Dhillon, Wiesenborn, Wolf-Hall, & Manthey, 2009;İbanoǧlu, 2001); however, these methods resulted in the addition of more moisture to the grain than required for milling, thus introducing the need for a drying step.…”

“…Dhillon et al (2009) evaluated acidified ozonated water (20.5 ppm ozone, 1.0% acetic acid) as an antimicrobial treatment for wheat. Also using a fluidized bed, Dhillon et al (2012) sprayed on buckwheat grain a solution containing a combination of acetic acid (5 ml/L) and acidic calcium sulfate (25 ml/L), resulting in reductions of 1.90 and 2.40 log CFU/g in APC and yeast/mold counts, respectively. In a follow-up study, Dhillon, Wiesenborn, Dhillon, and Wolf-Hall (2010) utilized a fluidized bed system to apply a combination of gaseous ozone (6 ppm), acetic acid (0.5%), and ozonated water (26 ppm) to reduce the microbial load of durum wheat grain.…”

“…A reduction in APC of 1.70 and 3.30 log CFU/g for yeast/mold counts was noted after the application of this treatment. Also using a fluidized bed, Dhillon et al (2012) sprayed on buckwheat grain a solution containing a combination of acetic acid (5 ml/L) and acidic calcium sulfate (25 ml/L), resulting in reductions of 1.90 and 2.40 log CFU/g in APC and yeast/mold counts, respectively.…”

“…Previous research studies have evaluated several methods to reduce the microbial load of wheat grain prior to milling. Early investigations on this topic included the application of antimicrobial agents such as chlorine and ozone by means of washing, soaking, and fluidization systems (Dhillon, Wiesenborn, Sidhu, & Wolf-Hall, 2012;Dhillon, Wiesenborn, Wolf-Hall, & Manthey, 2009;İbanoǧlu, 2001); however, these methods resulted in the addition of more moisture to the grain than required for milling, thus introducing the need for a drying step. Alternative methods for wheat decontamination have also been evaluated including atmospheric cold plasma and pulsed light (Aron-Maftei, Ramos-Villarroel, Nicolau, Martín-Belloso, & Soliva-Fortuny, 2014;Los et al, 2018).…”