Journal of Food Composition and Analysis 115 (2023) 105002 Available online 28 October 2022 0889-1575/© 2022 Elsevier Inc. All rights reserved. The Effect of Boiling and in Vitro Digestion on the Carotenoid Content of Colored-grain Wheat Barbora Bure ˇ sov´ a a, * , Lubo ˇ s Paznocht a , Veronika Jaroˇ sov´ a b , Ivo Doskoˇ cil c , Petr Martinek d a Department of Chemistry, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamýck´ a 129, 165 00 Prague-Suchdol, Czech Republic b Department of Food Science, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamýck´ a 129, 165 00 Prague-Suchdol, Czech Republic c Department of Microbiology, Nutrition and Dietetics, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamýck´ a 129, 165 00 Prague-Suchdol, Czech Republic d Agrotest Fyto, Ltd., Havlíˇ ckova 2787/121, 767 01 Kromˇ eˇ ríˇ z, Czech Republic A R T I C L E INFO Keywords: Carotenoid thermostability Cereal-based food HPLC-DAD Human nutrition Lutein Xanthophylls ABSTRACT The boiling of colored-grain wheat kernels resulted in a more pronounced loss of total carotenoids compared to in vitro digestion (27.3% vs. 12.1%). After both boiling and digestion, the highest carotenoid content was preserved in Citrus and Bona Vita wheats with yellow endosperm (2.34 and 1.88 μg/g), which is more than six times the content retained in the digested material of red and blue varieties. Esterifed carotenoids exhibited subaverage heat-resistance, as their content dropped to 58.0% after boiling, while decreasing only slightly due to digestion (to 53.4%). The stability of free zeaxanthin, lutein, and β-carotene differed signifcantly throughout boiling (92.3% > 72.3% > 27.1%) and subsequent digestion (68.3% > 60.1% > β-carotene was reduced completely). Exposure to high temperatures and other factors in play during digestion (i.e. acidic environment) resulted in lutein E/Z isomerization, mainly refected by an increase in 9- and 9’-Z-lutein content to 111% and 225%. 1. Introduction Wheat is one of the leading crops for global food security, not least because of its suitable characteristics for storage and thus for ensuring food reserves. In many European countries it is indisputably the most intensively cultivated cereal, used mainly for milling into four and for the subsequent manufacturing of baked goods and pasta products or malt; moreover, it is used as a feed raw material, and to a lesser extent for ethanol or starch production (Narwal et al., 2020). In addition to the traditional so-called red-grain varieties, wheat genotypes with unusually colored kernels, possessing a unique new ability to synthesize and store anthocyanins in the outer layers of the grain and/or with a substantially higher carotenoid content in the endosperm, have been bred in recent years (Lachman et al., 2017). In the Czech Republic the latest of these unconventional varieties is AF Zora, registered in 2021, with a black grain color given by the combination of genes for blue aleurone (Ba) and purple pericarp (Pp). In previous years, other varieties with unusual grain colors caused by an increased anthocyanin content were regis- tered, namely AF Oxana (Ba) in 2019 and AF Jumiko (Pp) in 2018 (VUKROM, 2021). Varieties rich in yellow carotenoid pigments, such as Bona Vita and Citrus, were registered earlier in Slovakia and Germany (Fuˇ cíkov´ a and Nov´ aˇ cek, 2014; ÚKZÚZ, 2018). Continuous breeding ef- forts in the feld of colored-grain wheat aim to enhance public health by implementing new varieties in the food industry, enabling the smart and cost-effective production of nutrient-dense foods, the consumption of which could contribute to the prevention of many degenerative diseases, since carotenoids and anthocyanins generally act as antioxidants in the human body (Kotíkov´ a et al., 2016). However, commonly used methods of wheat grain processing - the baking of leavened (Paznocht et al., 2019; Eli´ aˇ sov´ a et al., 2020) and unleavened bread (Bureˇ sov´ a et al., 2021), puffng and extrusion (Paz- nocht et al., 2021), and pasta production (Hidalgo et al., 2010; Oduro-Obeng et al., 2021) - cause various degradation rates of valuable phytochemicals. It has been found that the most relevant factors causing Abbreviations: Ba, blue aleurone; i.v., initial value; Pp, purple pericarp; SGF, simulated gastric fuid; SIF, simulated intestinal fuid; SSF, simulated salivary fuid; TCC, total carotenoid content; Ye, yellow endosperm. * Corresponding author. E-mail address: buresovab@af.czu.cz (B. Bureˇ sov´ a). Contents lists available at ScienceDirect Journal of Food Composition and Analysis journal homepage: www.elsevier.com/locate/jfca https://doi.org/10.1016/j.jfca.2022.105002 Received 9 June 2022; Received in revised form 7 September 2022; Accepted 25 October 2022