310 CEREAL CHEMISTRY Effects of Genotype and Environment on Phenolic Acids Content and Total Antioxidant Capacity in Durum Wheat Daniela Martini, 1,2 Federica Taddei, 1 Isabella Nicoletti, 3 Roberto Ciccoritti, 1,2 Danilo Corradini, 3 and Maria Grazia D’Egidio 1,4 ABSTRACT Cereal Chem. 91(4):310–317 In cereals, phenolic acid (PA) content and total antioxidant capacity (TAC) may have a wide range of variability, probably because of several factors influencing the occurrence of grain antioxidants, which include genotype, environment, and their possible interactions. How- ever, only a few studies have investigated the influence of these fac- tors on durum wheat. In the present study, we investigated the impact of the genetic and environmental factors on the profile and content of PAs occurring as soluble free, soluble conjugated, and insoluble bound compounds, as well as on the TAC level, in three genotypes of durum wheat grown in three different Italian agroclimatic areas during two crop years. The results show that genotype, environment, and crop year have highly significant effects on TAC levels and on PA contents. In particular, TAC and free PAs are most influenced by year, whereas conjugated and bound PAs are most influenced by environ- ment × year and genotype, respectively. Therefore, it is evidenced that genetic and environmental factors affect the antioxidant activity and the content of the three forms of PAs in durum wheat to different extents. Durum wheat (Triticum durum spp.) is a minor crop worldwide, but it plays a dominant role in the Mediterranean areas, where derived products (pasta, bread, couscous, and bulgur) are funda- mental in the human diet. According to food-making properties of the grains and nutri- tional guidelines (National Institute of Research on Foods and Nutrition 2003; NHMRC 2003; USDA and HHS 2010), consum- ers are presently requiring more and more whole grains. In this context, from a health point of view, there is information indicat- ing an association between regular consumption of whole grains and lower risk of chronic diseases such as type 2 diabetes and cardiovascular diseases (de Munter et al 2007; Mellen et al 2008; Ye et al 2012). The specific roles of the bioactive compounds of the grains and their protective mechanisms on human health have not been fully elucidated. However, evidence has suggested that the health-promot- ing effects of whole grains appear to result from the presence of bioactives including fiber and phenolic compounds, such as phe- nolic acids (PAs) (Björck et al 2012; Gani et al 2012). PAs, derivatives of hydroxycinnamic acid and hydroxybenzoic acid, are the most abundant phenolic compounds in cereals and specifically in wheat (Mattila et al 2005), in addition to couma- rins, proanthocyanidins, stilbenes, lignans, and flavonoids (Dinelli et al 2009). These compounds mostly occur in the outer layers of grains, where they are highly concentrated, whereas only trace amounts are found in the endosperm, so they are generally lost during the milling and refining processes (Lempereur et al 1997; Slavin et al 2000; Adom et al 2005). Among PAs, ferulic and sinapic acids are usually dominant, al- though also p-coumaric, vanillic, syringic, p-hydroxybenzoic, and other acids are commonly found (Li et al 2008). These com- pounds occur in three forms: soluble free; soluble conjugated, mainly linked to low-molecular-weight components such as sug- ars and sterols; and insoluble bound, usually linked to cell wall polymers (e.g., arabinoxylans and lignin) (Adom and Liu 2002; Graybosch et al 2009). The bound form is the most abundant one; Li et al (2008) reported that it accounts for about 80% of total PAs on a weight basis in durum wheat as well as in spelt, winter, and spring wheat. Furthermore, there is information showing that unlike soluble fractions, bound PAs are not metabolized in the stomach and up- per intestinal digestion and finally reach the lower gastrointesti- nal tract, where they can be released via the gut microflora (Andreasen et al 2001; Slavin 2004). In this context they can act as traps for oxidative compounds, providing an antioxidant envi- ronment that might partially explain their protective role in co- lon cancer (Fardet 2010). Phenolic compounds, and in particular PAs, are believed to prominently contribute to the antioxidant properties of wheat and other cereals, for which a relationship with the antioxidant capac- ity of grains was found (Zieliński and Kozlowska 2000; Hirawan et al 2010). In cereals, besides PAs, several compounds contribute to the antioxidant properties (e.g., tocopherols, lignans, and carotenoids); thus, the whole antioxidant activity is often evaluated by the anal- ysis of total antioxidant capacity (TAC). TAC in complex foods such as cereals results from hydrophilic and lipophilic compounds, and for a long time their separate ex- traction has been considered indispensable to properly evaluating this parameter. Nevertheless, the separate extraction of these two classes of compounds with different characteristics impedes eval- uating their synergistic effects. This outcome may be, at least in 1 Consiglio per la Ricerca e la Sperimentazione in Agricoltura, Unità di Ricerca per la Valorizzazione Qualitativa dei Cereali (CRA-QCE), Via Cassia 176, 00191 Rome, Italy. 2 Università Campus Bio-Medico, Via Alvaro del Portillo 21, 00128 Rome, Italy. 3 Istituto di Metodologie Chimiche, Consiglio Nazionale delle Ricerche, Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Montelibretti (RM), Italy. 4 Corresponding author. Phone: +39-06-3295705. E-mail: mariagrazia.degidio@ entecra.it http://dx.doi.org/10.1094/ CCHEM-09-13-0201-CESI © 2014 AACC International, Inc.