Sensory and Hedonic Effects of FAAA-conjugates Added to Food Products

FAAA conjugates are compounds containing different long-chain fatty acids and simple amino acids. They are involved in multiple signalling pathways playing a role in the regulation of homeostatic and non-homeostatic eating behaviour (Jager \& Witkamp, 2014). FAAA-conjugates are naturally occurring in various animal and plant food sources, yet their dietary relevance and exact mechanism of action remains unclear. Notwithstanding, they have been related to improved food sensations and hedonic effects (Jager \& Witkamp, 2014; Witkamp, 2018; Yoshida et al., 2013). FAAA compounds have been declared GRAS by FEMA, which guarantees their safe use in commercially available food products (Flavour Extract Manufacturers Association, 2018).

According to preliminary observations provided by the research and development department (R\&D) of Givaudan, the addition of specific FAAA-conjugates to a range of food products resulted in an enhancement of several sensory- and hedonic effects in product evaluation. Panellists reported accentuated palatability; aftertaste masking; enhanced fat, sweet, salt and umami perception; and mouthfeel improvement. However, the reproducibility of these results is questionable, as substantial variation in the effects arose both within and between a small sample of volunteers. It is unclear whether these effects are specific for and dependent on integration of these conjugates in a certain food matrix, or if they have a more general boosting effect, relevant for taste or flavour. Perhaps the boosting effect also affects other sensory domains (e.g. vision).

The aforementioned reported sensory/hedonic effects could be attributed to what has been described in literature as the kokumi sensation, which is related to activation of calcium-sensing receptors on the human tongue, albeit the exact mechanism remains to be elucidated (Feng, Zhang, Zhuang, Zhou, \& Xu, 2016; Kuroda \& Miyamura, 2015; Ohsu et al., 2010). Although Kokumi is associated with taste perception, it is most likely not a primary taste, since its effects exist in the context of other taste compounds. On their own, kokumi compounds elicit only very slight or no taste sensations but incorporated in a food matrix they can enhance other taste sensations. The threshold concentration of kokumi compounds in a plain water solution to induce a taste sensation is usually very high, while the threshold concentration in food to enhance other taste sensations can be very low. (Dunkel, Koster, \& Hofmann, 2007; Feng et al., 2016; Kuroda \& Miyamura, 2015).

On the basis of preliminary testing done by R\&D Givaudan, the study described in the current protocol aims to systematically investigate the sensory and hedonic effects of FAAA-conjugates. To do so, specific FAAA-conjugates will be integrated into two food products (one sweet (chocolate milk) and one savoury (salad dressing), which will be sensorially and hedonically evaluated. Furthermore, the dependency of FAAA-conjugates on the food matrix will be studied by administering them separately from food products. An untrained panel will be used, since consumers are not only capable of providing accurate and reliable information about product sensory characteristics, but can also serve as a measure of potential performance of the product in the marketplace (Ares \& Varela, 2017; Lawless \& Heymann, 2010).

If results are in line with the aforementioned preliminary observations, they can add to the body of knowledge and underpin future studies investigating the kokumi sensation and the mechanistic background of FAAA-conjugate effects. Moreover, food product reformulation with the use of FAAA-conjugates could positively impact a wide range of consumers. Due to their boosting sensory/hedonic effects, enriching foods with FAAA-conjugates has the potential to reduce sugar, fat and salt content in a wide range of food products without compromising on experienced flavour, thereby reducing sugar, fat and salt intake and their harmful effects. More importantly, the elderly and seriously ill patients could benefit from the palatability-enhancing effects ascribed to kokumi molecules, which could stimulate appetite and help reverse weight loss (Witkamp, 2018).

1. OBJECTIVES

Primary Objective(s):

The primary objective of the current study is to determine if there is an objective perceivable difference between plain and FAAA-enriched versions of selected food products and describe sensory and/or hedonic differences between them, using a combination of discrimination testing, descriptive analyses and hedonic tests.

Secondary Objective(s):

The secondary objective is to assess the dependency of FAAA-conjugates on the food matrix, by separating administration of compound and product and assessing how separation affects sensory and hedonic evaluation.