Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem Simultaneous enrichment of grape pomace with γ-linolenic acid and carotenoids by solid-state fermentation with Zygomycetes fungi and antioxidant potential of the bioprocessed substrates Francisc Vasile Dulf a, ⁎ , Dan Cristian Vodnar b, ⁎ , Monica Ioana Toşa c , Eva-Henrietta Dulf d a Faculty of Agriculture, Department of Environmental and Plant Protection, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, Calea Mănăştur 3-5, 400372, Romania b Faculty of Food Science and Technology, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, Calea Mănăştur 3-5, 400372, Romania c Faculty of Chemistry and Chemical Engineering, University Babeş-Bolyai, Biocatalysis Research Group, Arany János 11, 400028 Cluj-Napoca, Romania d Faculty of Automation and Computer Science, Department of Automation, Technical University of Cluj-Napoca, G. Baritiu 26-28, 400027 Cluj-Napoca, Romania ARTICLE INFO Keywords: Solid- state fermentation Actinomucor elegans Umbelopsis isabellina γ-Linolenic acid Carotenoids Polyphenols Grape pomace ABSTRACT Two filamentous fungi (Actinomucor elegans and Umbelopsis isabellina), were tested for their ability to enrich white grape pomace simultaneously with both γ-linolenic acid (GLA) and carotenoids through solid-state fer- mentation (SSF) processes. U. isabellina presented higher ability to produce GLA-rich lipids (composed mainly of neutral fractions) than A. elegans (the 6-th day of SSF: 378.85 mg/100 g of pomace –U. isabellina and 193.36 mg/ 100 g of pomace– A. elegans). The amounts of β-carotene and lutein for both SSFs gradually increased until the end of the fermentation processes. The effect of fermentation time on the phenolic content and antioxidant activity of grape pomace was also studied. The SSF with A. elegans increased significantly total phenolic and flavonoid contents and DPPH scavenging activity of grape popmace. These bioprocessed grape pomaces with significant amounts of carotenoids and GLA-rich lipids (> 94% nutritionally-valuable polyunsaturated fatty acids at the sn-2 position) could be very attractive for food industry. 1. Introduction Grape (Vitis spp.) is one of the most widely grown fruit crops in the world. In 2017, around 7 million hectares were dedicated worldwide to the production of about 74.28 million tonnes of grapes, of which more than 35% correspond to European producers (FAO, 2017). About 75% of the world grape production is destined for wine production (Beres et al., 2017). The wine industry generates huge amounts of solid waste (grape pomace), consisting mainly of the remaining skin, seeds (38–52% on a dry matter basis) and stalks, representing about 25% of the weight of the grape used in the winemaking process (Maier, Schieber, Kammerer, & Carle, 2009). The grape pomaces are composed of water (55–75%), proteins (6–15%), lipids, carbohydrates, minerals, phenolic and non-phenolic antioxidants (e.g. tocopherols and vitamin C) and low amounts of β- carotene, depending on the winemaking procedure, the cultivar and climatic and cultivation conditions (Beres et al., 2017; Maier et al., 2009). Since grape pomaces contain a wide spectrum of nutritional compounds as mentioned above, studies have been conducted to incorporate this underutilised by-product in human diet (Beres et al., 2017; Tseng & Zhao, 2013). Moreover, the oil pressed from grape seeds (8–16%, w/w) is considered a high-value product with numerous ap- plications in food, cosmetic and pharmaceutical industries. It consists mainly of triglycerides rich in unsaturated fatty acids such as linoleic (C18:2, n-6) and oleic (C18:1, n-9) acids (comprising together more than 68% of total fatty acids) (Beres et al., 2017). However, several studies have shown that the fat from grape seed lacks a range of im- portant nutrients, especially some dietetic valuable PUFAs (other than linoleic acid) and carotenoid pigments (Lachman et al., 2015). These compounds are indispensable for human body due to their healthy, dietary and functional properties (Eggersdorfer & Wyss, 2018; Saini & Keum, 2018). Recent reports indicate that solid-state fermentation (SSF) is one of the most qualified techniques for natural enrichment of solid materials with desired biomolecules (Mudroňová et al., 2018). SSF refers to the aerobic fungal degradation of a fermentable organic solid substrate in the absence of free water in order to obtain various value-added pro- ducts. This type of biotreatment is successfully used in food industry to https://doi.org/10.1016/j.foodchem.2019.125927 Received 26 June 2019; Received in revised form 15 November 2019; Accepted 18 November 2019 ⁎ Corresponding authors at: University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, Calea Mănăştur 3-5, 400372 Cluj-Napoca, Romania. E-mail addresses: francisc.dulf@usamvcluj.ro (F.V. Dulf), dan.vodnar@usamvcluj.ro (D.C. Vodnar). Food Chemistry 310 (2020) 125927 Available online 03 December 2019 0308-8146/ © 2019 Elsevier Ltd. All rights reserved. T