Effect of ultra-superheated steam on aflatoxin reduction and roasted peanut properties

Superheated steam processing of cereals and cereal products: A review

The concept of superheated steam (SS) was proposed over a century ago and has been widely studied as a drying method. SS processing of cereals and cereal products has been extensively studied in recent years for its advantages of higher drying rates above the inversion temperature, oxygen-free environment, energy conservation, and environmental protection. This review provides a brief introduction to the history, principles, and classification of SS. The applications of SS processing in the drying, enzymatic inactivation, sterilization, mycotoxin degradation, roasting, and cooking of cereals and cereal products are summarized and discussed. Moreover, the effects of SS processing on the physicochemical properties of cereals and the qualities of cereal foods are reviewed and discussed. The applications of SS for cereal processing and its effects on cereal properties have been extensively studied; however, issues such as the browning of cereal foods, thermal damage of starch, protein denaturation, and nutrition loss have not been comprehensively studied. Therefore, further studies are required to better understand the mechanism of the quality changes caused by SS processing and to expand the fields of application of SS in the cereal processing industry. This review enhances the understanding of SS processing and presents theoretical suggestions for promoting SS processing to improve the safety and quality of cereals and cereal products.

Cloning and expression of the catalase gene (KatA) from Pseudomonas aeruginosa and the degradation of AFB1 by recombinant catalase

BACKGROUND

Aflatoxin B₁ (AFB₁ ) poses a severe threat to human and animal health. Countries worldwide have invested considerable manpower and material resources in degrading aflatoxins. Enzyme degradation is the most efficient and environmentally friendly approach for modifying aflatoxin into less toxic molecules. Catalase is commonly used as a detoxification agent to decrease the contamination levels of aflatoxins in animal feeds. This study aimed to obtain recombinant catalase via gene engineering and determined whether a recombinant catalase could degrade AFB₁ .

RESULTS

The catalase gene (KatA) from Pseudomonas aeruginosa was cloned and expressed in Escherichia coli, and the expression conditions of this recombinant catalase were optimized. The recombinant catalase was isolated and purified using Ni-chelating affinity chromatography, and its ability to degrade AFB₁ was evaluated. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the expressed of catalase was approximately 55.6 kDa, which was subsequently purified using Ni-chelating affinity chromatography. The degradation rate of AFB₁ by recombinant catalase in the presence of syringaldehyde was 38.79%.

CONCLUSION

The degradation of AFB₁ by a recombinant catalase has been reported for the first time. This study provides a new paradigm for the use of recombinant catalases in degrading AFB₁ in food and feed. © 2022 Society of Chemical Industry.

Influence of ozonation and roasting on functional, microstructural, textural characteristics, and aflatoxin content of groundnut kernels

The present study was conducted to evaluate the influence of ozonation, roasting and their combination on the moisture content, color, functional, structural, textural components, and aflatoxins in groundnut kernels. Samples were subjected to three treatments namely, dry roasting (R): 166°C for 7 min; gaseous ozone treatment (O): 6 mg/L for 30 min; combined ozonation-roasting (OR): gaseous ozonation at 6 mg/L for 30 min followed by dry roasting at 166°C for 7 min. The ozonated-roasted samples had the lowest moisture content (3.45%), the highest total phenolic content (4.18 mg gallic acid equivalents/100 g), and antioxidants capacity (69.59%). The treatments did not induce significant changes in color of kernels (p < .05). Scanning electron microscopy indicated cracking of granules in roasted and swelling in ozonated kernels whereas more uniform orientation of granules was observed in ozonated-roasted kernels. Roasted and ozonated kernels indicated a significant reduction of fracturability force to 54.60 and 14.11%, respectively, whereas ozonated-roasted samples demonstrated a nonsignificant increase (4.37%). An increase in wave number of ozonated samples to 3,289.37 cm^-1 in Fourier transform infrared (FTIR) spectrum (FTIR) indicated stretching in OH groups. FTIR spectrum of ozonated-roasted kernels suggested the formation of a new compound with CC and CC groups. The major aflatoxin B1 was reduced to maximum, that is, 100% in ozonated-roasted kernels followed by ozonated (80.95%) and roasted (57.14%) samples. The findings indicate that the ozonation-roasting treatment had a prominent role in the enhancement of functional compounds, structural and textural attributes along with the considerable reduction in aflatoxin content.

Aflatoxin reduction in nuts by roasting, irradiation and fumigation: a systematic review and meta-analysis

The present study aimed to investigate the reduction of aflatoxins as a potent hazard for human health in nuts during roasting, irradiation, and fumigation processes. A systematic search was performed in PubMed, Scopus, and ISI Web of Science on 6 April 2020 to find interventional studies assessing the effects of roasting, fumigation, and irradiation methods on total and individual aflatoxins concentration in nuts. Study-specific results were pooled by using a random-effects model. A total of 19 trials were included in the analyses. In most studies, the influence of method on aflatoxin reduction was assessed on peanuts. The results showed that the roasting method significantly reduced aflatoxin B1, B2, G1, and G2 concentrations by 46.91%, 30.66%, 40.88%, and 26.19%, respectively. Such results for the fumigation method were 20.88% and 22.56% for aflatoxin B1 and aflatoxin total, respectively. There was a 58.60% reduction in aflatoxin B1 and a 74.97% reduction in aflatoxin total concentrations in nuts following the irradiation method. The findings indicated that the evaluated processes could be influential for reducing aflatoxin levels in nuts.