# Effect of Asparaginase Treatment on Biscuit Volatile Compounds
## 1 Introduction  
Maillard reaction (MR) plays a key role in thermal treatments during the processing of cereal-based foods, being responsible for several attributes related to quality and safety [1, 2, 3]. Undesired effects of the MR have also been highlighted, such as heat damage of the proteins, assessable through the determination of furosine, and neo-formation of chemical contaminants, such as acrylamide and 5-hydroxymethylfurfurfural [4, 5]. Thus, measures to mitigate the extent of these unintended effects of MR, while keeping the desired effects on food quality, need to be carefully considered. This study will investigate one of the mitigation strategies used for reducing acrylamide formation, focusing on the use of the enzyme asparaginase in the conventional production of shorthead biscuits. Asparaginasecatalyses the conversion of asparagine into aspartic acid and ammonia by hydrolysing the amide group in asparagine's side chain [4; 6]. This enzyme selectively degrades asparagine, which is the primary precursor of acrylamide and, generally, is not regarded as a major determinant of flavour or colour in thermal treated foods. In cereal-based products, asparagine, rather than reducing sugars, is considered the limiting factor in acrylamide formation [6]. The free asparagine content in widely used cereal species has been reported to range from 426 to 1179 mg kg\({}^{-1}\)[7]. Commercial asparaginase preparations, derived from _Aspergillus oryzae_ and _Aspergillus niger_, are widely used in industrial applications and have been deemed safe by regulatory bodies such as FAO/WHO and the FDA [8]. The use of asparagine has been considered one of the most promising strategies to limit acrylamide formation in bakery products, even by virtue of the limited impact on the sensory quality. In particular, several investigations have demonstrated that the combination of asparaginease addition and controlled resting time can reduce acrylamide formation in biscuits, along with the formation of other undesired MR products, such as furfurals [9; 10; 11]. However, only a few studies explored in detail the quality and sensorial attributes of biscuits after the use of asparaginase, generally focusing on the effects on taste and colour, and with little information on the aroma of the final product [11; 12; 13]. It is known that the addition of asparaginase modifies the amino acid composition of the dough [4; 6], that amino acids are key reagents in the MR, and that MR is one of the main pathways for the formation of volatile organic compounds (VOCs) in biscuits [1; 14]. Thus, it is conceivable that this treatment may influence VOC formation. However, the literature does not clearly establish whether asparaginase treatment affects aroma quality or the significance of such an effect. On the other hand, it is known that VOCs are formed not only through MR but also from caramelisation reactions and lipid oxidation [1]. Varying baking times and temperatures have been shown to significantly impact the VOC formation in baked products and manipulation of these parameters can modify to a large extent the progress of the above-mentioned chemical pathways of VOC formation [14]. Key volatile compounds of cereal-based baked foods formed through these reactions belong to the chemical classes of alcohols, aldehydes, pyrazines, ketones, acids, furuns, alkanes, sulphur compounds, pyrroles, and others [14]. Beyond aroma, MR plays a key role in determining also the colour of baked foods. Colour development has been attributed to the final stage of the MR [1]. In addition, a strong positive relationship between acrylamide concentration and colour development has been reported in the preparation of cereal-based baked products [15]. Moreover, no significant changes in colour associated with asparaginease treatment have been observed in baked foods [9; 16]. Given the key role of sensory quality in determining consumers' food choices, it is essential to evaluate the effects of asparaginase treatment on the sensory attributes of biscuits.