## 1 Introduction  
Fermented meat products, such as chorizo sausage, have diverse odors due to volatile compounds derived from the presence of spices, and those generated during fermentation and ripening. The role of food odors is highly relevant to the overall acceptance of a product [1] and it is a key attribute influencing the amount of food that is ingested, because we perceive the smell (orthonasal) before consumption [2]. [PERSON] et al. [3] showed that odor and visual texture were the key attributes in deciding the amount of food that is ingested. The properties of chorizo have been widely studied, such as its sensory properties [4; 5; 6; 7; 8], its volatile compound profile during ripening [9; 10], and an evaluation of different brands of Pamplona chorizo [11]. Other investigations using chorizo have focused on the effect of ripening time and/or different amounts of some ingredients (fat, starter culture, antioxidants) on volatile compounds, as well as their relationship to the acceptance of the product [12; 13] or the effect on the sensory properties [12; 13], although sensory tests were only carried out on the final product. Similar studies have been undertaken with other dry-fermented sausages [14; 15; 16; 17]. In some cases, the studies omitted spices to avoid interference in the volatile analysis [18; 19]. However, the flavor of these types of products is the result of a complex equilibrium between spices and the variability of volatile compounds derived from different reactions [20]. All of these studies had some limitations, focusing on only a few odors or the global intensity of flavor and/or odor, or the sensory information was focused on preferences and overall acceptability at the end of ripening. Therefore, changes in the odor profile during the whole process of development have been poorly studied in fermented sausages such as chorizo. Gas Chromatography-Olfactometry (GC-O) has also been used to study fermented sausage aromas [17; 21; 22]. The technique consists of the elution of a compound mixture through a column in GC coupled with the human olfactory system as a detector. It allows the active odor compounds that are in suprathreshold odor concentrations to be detected, although GC-O detects these active compounds in isolation [23]. It is important to note that the odors we perceive are not due to a single compound; the perception of an odor is the interaction of volatile compound mixtures, with the odorant receptors in a combinatory strategy where one molecule is recognized by more than one receptor, and one receptor recognizes several molecules [24]. Consequently, the odor/aroma we perceive depends on which receptors are activated, so it is also important to understand the pattern of volatile active compounds that activate the receptors that generate the signals for specific odors. To achieve this, multivariate statistics can be used as tools to explore relationships between volatile composition and odor/aroma perception in foods. Principal Component Analysis (PCA) is the most common multivariate statistical technique used to evaluate the relationship between volatile and sensory information, but it is only an exploratory method, providing an overview of the data. Other modeling techniques must also be explored [25]. Partial least squares (PLS) modeling combines features from PCA and multiple regression to predict a set of dependent variables, the sensory data, from a large set of independent variables, the predictors, which are the volatile compounds [26]. PLS has been applied in other studies on meat products [27; 28; 29; 30], Salami Milano sausage [31], pac choi [32], roasted peanuts [33], and wines [34; 35]. To our knowledge, there is no other study that describes the volatile compound pattern which generates the odors in chorizo during the ripening process using this statistical method.