By-products of pyro-bituminous shale as amendments in Brazilian vineyards: Influence on polyphenolic composition of Cabernet Sauvignon wines

• By-products of pyro-bituminous shale could be an alternative to traditional amendments.
• Wines from treated grapevines enhanced some anthocyanin compounds.
• Conventional shale combined with by-products of pyro-bituminous shale gave better results.

Liming soils is a common technique used in Brazil due to their acidity and deficiencies of calcium and magnesium. Therefore, the employments of amendments play a key role on the plant development. Looking for a model of agroecological production, the application of by-products of pyro-bituminous shale, as partial or total substitutive of conventional amendments, to grapevines and its effect on wine phenolic compounds have been evaluated. Field trials were aimed to compare the effect of different doses of conventional and limestone shale from by-products of pyro-bituminous. Applications of 0, 1000, 2000, 3000, 4000 and 0 kg ha− 1 of limestone shale combined with 0, 3000, 2000, 1000, 0 and 4000 kg ha− 1 of conventional shale were conducted in a two-year field trial, 2010 and 2011. Results revealed that climate conditions had a great influence on phenolic content of wines in both vintages. Hydroxycinnamic acids and stilbenes were the families less affected by the different amendment treatments applied to vines. Among flavonols, quercetin and myricetin were more susceptible compounds to some amendment treatments tested. Anthocyanins were the most affected group elucidating higher concentrations in wines from treated grapevines than those founded in control wines. Amendments treatments enhanced the content of some anthocyanins such as 3-O-glucosides of delphinidin, petunidin and malvidin, acetyl derivatives of petunidin, peonidin and malvidin, and p-coumaroyl derivative of peonidin. Although small differences were found among wines from grapevines with amendments treatments, it seemed that the combined used of conventional and pyro-bituminous shale gave better results.