A Ph.D thesis from the University of Milan-Bicocca in English is publicly available. The thesis gives a good overview of DNA barcoding, NGS (Next Generation Sequencing) and metabarcoding, and isothermal nucleic acid amplification. The research carried out looked at applying DNA barcoding to processed foods, which required smaller DNA fragments. However, the approach is not suitable for mixed species samples, and NGS and metabarcoding approaches were more successful. Finally, an isothermal amplification assay was applied to authenticate truffles.
You can read the 253 page thesis here