Influence of Temperature, Solvent and pH on the Selective Extraction of Phenolic Compounds from Tiger Nuts by-Products: Triple-TOF-LC-MS-MS Characterization

Abstract

The aim of this study was to assess the effect of temperature, solvent (hydroethanolic mixtures) and pH on the recovery of individual phenolic compounds from “horchata” by-products. These parameters were optimized by response surface methodology and triple-TOF-LC-MS-MS was selected as the analytical tool to identify and quantify the individual compounds. The optimum extraction conditions were 50% ethanol, 35 °C and pH 2.5, which resulted in values of 222.6 mg gallic acid equivalents (GAE)/100 g dry matter and 1948.1 µM trolox equivalent (TE)/g of dry matter for total phenolic content (TPC) and trolox equivalent antioxidant capacity (TEAC), respectively. The extraction of phenolic compounds by the conventional solvent method with agitation was influenced by temperature (p = 0.0073), and more strongly, by the content of ethanol in the extraction solution (p = 0.0007) while the pH did not show a great impact (p = 0.7961). On the other hand, the extraction of phenolic acids was affected by temperature (p = 0.0003) and by ethanol amount (p < 0.0001) but not by the pH values (p = 0.53). In addition, the percentage of ethanol influenced notably the extraction of both 4-vinylphenol (p = 0.0002) and the hydroxycinnamic acids (p = 0.0039). Finally, the main individual phenolic extracted with hydroethanolic mixtures was 4-vinylphenol (303.3 μg/kg DW) followed by spinacetin3-O-glucosyl-(1→6)-glucoside (86.2 μg/kg DW) and sinensetin (77.8 μg/kg DW).

Effect of Different Green Extraction Methods and Solvents on Bioactive Components of Chamomile (Matricaria chamomilla L.) Flowers

“…In the production of extracts from natural sources various isolation techniques are combined while more and more attention is gained to the techniques focused to the principles of "green chemistry", which among other things assumes using environmentally safe and nontoxic solvents [8][9][10][11]. For the extraction of various phytochemicals, specifically polyphenolic compounds the efficient solvents are usually ethanol, methanol, glycerol and their water solutions [12][13][14][15]. However, more attention has been gained to the use of solvents Generally Recognized As Safe (GRAS), such as water [16].…”

Antibacterial, antifungal and antioxidant activity of Cleome coluteoides: An In Vitro Comparative Study between Leaves, Stems, and Flowers

“…also the extraction yields were affected by the polarity, solubility, concentration, pH, temperature and nature of the extraction solvents. 23 Hence, a proper solvent system has to be used for extraction of maximum amounts of potent antioxidant components from typical plant materials. 24 On the one hand; medicinal plants produce secondary metabolites that are responsible for their therapeutic properties.…”

Mechanism of Allium Crops Bulb Enlargement in Response to Photoperiod: A Review

“…Environmental factors, such as for example the day length, affect bulb enlargement and taste eminence in onion [33]. In onion, light range and quality impacts bulb formation and quality [34][35][36][37][38][39][40][41]. The bulb initiation and growth of further Allium species including garlic have been shown to be influenced by day length, temperature, and carbohydrates [42,43].…”