Research advancements in optical imaging and spectroscopic techniques for nondestructive detection of mold infection and mycotoxins in cereal grains and nuts

Abstract

Cereal grains and nuts are represented as the economic backbone of many developed and developing countries. Kernels of cereal grains and nuts are prone to mold infection under high relative humidity and suitable temperature conditions in the field as well as storage conditions. Health risks caused by molds and their molecular metabolite mycotoxins are, therefore, important topics to investigate. Strict regulations have been developed by international trade regulatory bodies for the detection of mold growth and mycotoxin contamination across the food chain starting from the harvest to storage and consumption. Molds and aflatoxins are not evenly distributed over the bulk of grains, thus appropriate sampling for detection and quantification is crucial. Existing reference methods for mold and mycotoxin detection are destructive in nature as well as involve skilled labor and hazardous chemicals. Also, these methods cannot be used for inline sorting of the infected kernels. Thus, analytical methods have been extensively researched to develop the one that is more practical to be used in commercial detection and sorting processes. Among various analytical techniques, optical imaging and spectroscopic techniques are attracting growers' attention for their potential of nondestructive and rapid inline identification and quantification of molds and mycotoxins in various food products. This review summarizes the recent application of rapid and nondestructive optical imaging and spectroscopic techniques, including digital color imaging, X-ray imaging, near-infrared spectroscopy, fluorescent, multispectral, and hyperspectral imaging. Advance chemometric techniques to identify very low-level mold growth and mycotoxin contamination are also discussed. Benefits, limitations, and challenges of deploying these techniques in practice are also presented in this paper.

A Preliminary Study to Classify Corn Silage for High or Low Mycotoxin Contamination by Using near Infrared Spectroscopy

“…Functional groups (CH, NH, and OH) in chemical components could exhibit characteristic absorption in the Vis/NIR region which would result in significant changes in specific spectral bands during fungal growth. These changes could be reflected by Vis/NIR spectrum and NIR hyperspectral imaging (HSI) as reported by Mishra et al [ 64 ].…”

Aflatoxins in Cereals and Cereal-Based Products: Occurrence, Toxicity, Impact on Human Health, and Their Detoxification and Management Strategies

“…Near-infrared spectroscopy, fluorescent spectroscopy, and multispectral and hyperspectral imaging are some commonly used techniques that allow the inexpensive and rapid detection of AFs in cereal grains such as wheat, maize, corn, sorghum, rice, etc. [ 140 , 141 , 142 ]. For instance, Liu et al [ 143 ] applied surface-enhanced Raman spectroscopy (SERS) combined with the QuEChERS sample pre-treatment technique for the trace-level detection of aflatoxin B1 in wheat and corn with high sensitivity and strong specificity.…”

Occurrence of mycotoxins in pulses

“…NIRS is classified as an optical detection method among the rapid detection techniques. Optical methodologies for detecting mycotoxins in cereals and other commodities have been extensively investigated, as shown by reviews on this topic (Jia et al., 2020; Fox & Manley, 2013; Mishra et al., 2021; Tao et al., 2018). These reviews indicate an interest in further developing this type of technology to be applied at the industrial level for real‐time monitoring (e.g., online detection).…”