Replacement of Nitrite in Meat Products by Natural Bioactive Compounds Results in Reduced Exposure to N-Nitroso Compounds: The PHYTOME Project

Genetic Variability Impacts Genotoxic and Transcriptome Responses in the Human Colon after the Consumption of Processed Red Meat Products and Those with Added Phytochemical Extracts

The PHYTOME study investigated the effect of consuming processed meat products on outcomes related to colorectal cancer risk without testing the impact of genetic variability on these responses. This research aims to elucidate the genetic impact on apparent total N-nitroso compound (ATNC) excretion, colonic DNA adduct formation, ex vivo-induced DNA damage, and gene expression changes in colon biopsies of healthy participants. Through a systematic literature review, candidate polymorphisms were selected and then detected using TaqMan and PCR analysis. The effect of genotype on study outcomes was determined via a linear mixed model and analysis of variance. Machine learning was used to evaluate relative allele importance concerning genotoxic responses, which established a ranking of the most protective alleles and a combination of genotypes (gene scores). Participants were grouped by GSTM1 genotype and differentially expressed genes (DEGs), and overrepresented biological pathways were compared between groups. Stratifying participants by ten relevant genes revealed significant variations in outcome responses. After consumption of processed red meat, variations in NQO1 and COMT impacted responses in ATNC levels (µmol/L) (+9.56 for wildtype vs. heterozygous) and DNA adduct levels (pg/µg DNA) (+1.26 for variant vs. wildtype and +0.43 for variant vs. heterozygous), respectively. After phytochemicals were added to the meat, GSTM1 variation impacted changes in DNA adduct levels (-6.12 for deletion vs. wildtype). The gene scores correlated with these responses and DEGs were identified by GSTM1 genotype. The altered pathways specific to the GSTM1 wildtype group included 'metabolism', 'cell cycle', 'vitamin D receptor', and 'metabolism of water-soluble vitamins and co-factors'. Genotype impacted both the potential genotoxicity of processed red meat and the efficacy of protective phytochemical extracts.

Analysis of cell-specific transcriptional responses in human colon tissue using CIBERSORTx

Diet is an important determinant of overall health, and has been linked to the risk of various cancers. To understand the mechanisms involved, transcriptomic responses from human intervention studies are very informative. However, gene expression analysis of human biopsy material only represents the average profile of a mixture of cell types that can mask more subtle, but relevant cell-specific changes. Here, we use the CIBERSORTx algorithm to generate single-cell gene expression from human multicellular colon tissue. We applied the CIBERSORTx to microarray data from the PHYTOME study, which investigated the effects of different types of meat on transcriptional and biomarker changes relevant to colorectal cancer (CRC) risk. First, we used single-cell mRNA sequencing data from healthy colon tissue to generate a novel signature matrix in CIBERSORTx, then we determined the proportions and gene expression of each separate cell type. After comparison, cell proportion analysis showed a continuous upward trend in the abundance of goblet cells and stem cells, and a continuous downward trend in transit amplifying cells after the addition of phytochemicals in red meat products. The dietary intervention influenced the expression of genes involved in the growth and division of stem cells, the metabolism and detoxification of enterocytes, the translation and glycosylation of goblet cells, and the inflammatory response of innate lymphoid cells. These results show that our approach offers novel insights into the heterogeneous gene expression responses of different cell types in colon tissue during a dietary intervention.

Effects of sodium nitrite reduction, removal or replacement on cured and cooked meat for microbiological growth, food safety, colon ecosystem, and colorectal carcinogenesis in Fischer 344 rats

Epidemiological and experimental evidence indicated that processed meat consumption is associated with colorectal cancer risks. Several studies suggest the involvement of nitrite or nitrate additives via N-nitroso-compound formation (NOCs). Compared to the reference level (120 mg/kg of ham), sodium nitrite removal and reduction (90 mg/kg) similarly decreased preneoplastic lesions in F344 rats, but only reduction had an inhibitory effect on Listeria monocytogenes growth comparable to that obtained using the reference nitrite level and an effective lipid peroxidation control. Among the three nitrite salt alternatives tested, none of them led to a significant gain when compared to the reference level: vegetable stock, due to nitrate presence, was very similar to this reference nitrite level, yeast extract induced a strong luminal peroxidation and no decrease in preneoplastic lesions in rats despite the absence of NOCs, and polyphenol rich extract induced the clearest downward trend on preneoplastic lesions in rats but the concomitant presence of nitrosyl iron in feces. Except the vegetable stock, other alternatives were less efficient than sodium nitrite in reducing L. monocytogenes growth.

Novel strategies for controlling nitrite content in prepared dishes: Current status, potential benefits, limitations and future challenges

Sodium nitrite is commonly used as a multifunctional curing ingredient in the processing of prepared dishes, especially meat products, to impart unique color, flavor and to prolong the shelf life of such products. However, the use of sodium nitrite in the meat industry has been controversial due to potential health risks. Finding suitable substitutes for sodium nitrite and controlling nitrite residue have been a major challenge faced by the meat processing industry. This paper summarizes possible factors affecting the variation of nitrite content in the processing of prepared dishes. New strategies for controlling nitrite residues in meat dishes, including natural pre-converted nitrite, plant extracts, irradiation, non-thermal plasma and high hydrostatic pressure (HHP), are discussed in detail. The advantages and limitations of these strategies are also summarized. Raw materials, cooking techniques, packaging methods, and storage conditions all affect the content of nitrite in the prepared dishes. The use of vegetable pre-conversion nitrite and the addition of plant extracts can help reduce nitrite residues in meat products and meet the consumer demand for clean labeled meat products. Atmospheric pressure plasma, as a non-thermal pasteurization and curing process, is a promising meat processing technology. HHP has good bactericidal effect and is suitable for hurdle technology to limit the amount of sodium nitrite added. This review is intended to provide insights for the control of nitrite in the modern production of prepared dishes.

Physicochemical and Storage Characteristics of Pork Tteokgalbi Treated with Boesenbergia pandurata (Roxb.) Powder

This study investigates the physicochemical and storage characteristics of Tteokgalbi treated with various concentrations of Boesenbergia pandurata (Roxb.) powder (BP). BP is constituted mainly of carbohydrates (77.9%), possesses free-radical scavenging activity due to the presence of polyphenol and flavonoids, and is slightly acidic (pH 5.99). Five Tteokgalbi samples were treated with 0 (CON), 0.5% (B1), 1.0% (B2), or 2.0% (B3) of BP or 0.05% of ascorbic acid (REF). Compared to CON, BP-treated Tteokgalbi demonstrated significantly higher carbohydrate content and water-holding capacity and decreased cooking loss (%). BP-treated Tteokgalbi had significantly altered Hunter color properties, with decreased L* and increased b* values. Additionally, BP treatment significantly changed the textural properties by increasing the hardness (B3) and chewiness (B2 and B3) and decreasing the springiness (B3) of Tteokgalbi. Owing to the increased total polyphenol and flavonoid content, BP addition significantly enhanced the DPPH and ABTS radical scavenging activities of Tteokgalbi during vacuum-packed cold storage (0–14 days) at 5 °C. BP-treated Tteokgalbi maintained a higher pH compared to CON, and BP-treatment significantly suppressed 2-thiobarbituric acid, volatile basic nitrogen, and total microbial count during the cold storage period (7 and 14 days). Therefore, BP is a natural, edible antioxidant that may be applied to Tteokgalbi.