Detailed-chemistry DNS studies are becoming more common due to the advent of more powerful modern computer architectures, and as a result more realistic flames can be simulated. Such flames involve many alternative fuels such as syngas and blast furnace gas, which are usually composed of many species and of varying proportions. In this study, we evaluate whether some of the commonly used models for the scalar dissipation rate and flame surface density can be used to model such flames in the LES context. A priori assessments are conducted using DNS data of multi-component fuel turbu- lent premixed flames. These flames offer unique challenges because of their complex structure having many distinct consumption layers for the different fuel components unlike in a single-component fuel. Some of the models tested showed good agreement with the DNS data and thus they can be used for the multi-component fuel combustion.