Along with rapid global population growth comes the challenge of ensuring a food supply of optimum quantity and quality with respect to the environment and health. A dietary pattern that is higher in plant-based foods, including vegetables and legumes, and lower in salt is related to better health and lesser environmental impact [1
]. The growing presence of eating out of home in the Western diet [2
] could reflect changes in both the demand of consumers and the approach of food providers, thereby affecting the nutritional quality of food and, consequently, consumer health. Given that commercially processed food products and restaurant foods contribute substantially to meat [4
] and dietary salt intake [5
], developing healthy meals, which are plant-based and low in salt content, is a major challenge for the food industry and restaurant sector due to its impact on foods’ sensory profile and consumer acceptance [7
Dietary salt is an important component that is commonly used to make many food products and meals more flavorful. Nevertheless, salt intake around the world far exceeds nutritional requirements [8
], which is particularly worrisome given the strong evidence that high salt intake is related to hypertension, thereby increasing the risk of cardiovascular diseases [9
]. Global salt reduction programs are in place through awareness campaigns and governmental interventions [10
] in line with the World Health Organization (WHO) recommendation to reduce salt intake by 30% by 2025 [11
Furthermore, legumes are low in fat and densely packed with proteins, complex carbohydrates, fiber, and B-vitamins, and they are rich in several micronutrients, such as folate and iron [12
]. They are also known for their association with prevention of type 2 diabetes, cardiovascular disease, hypertension, obesity, and cancer [14
]. Despite the well-documented health benefits of legume consumption, the actual intake of legumes remains low [17
]. Among the reasons for the low consumption is flavor perception, which influences food choice [19
] and food intake [20
]. Flavor is described as the combination of taste (gustation), smell (olfaction), and chemical burn (trigeminal sensation) [21
]. Using a blend of herbs and spices to enhance the flavor and palatability of foods is a potential approach to assist consumers with reduced salt consumption, as well as to improve legume acceptance.
Ghawi et al. [22
] directly evaluated the impact of herbs and spices on enhancing liking of low-salt tomato soup. Participants were asked to rate the overall liking of three tomato soup samples: regular salt, low salt, and low salt with added herbs and spices. Overall liking, flavor, and texture liking were significantly increased only for the low salt with added herbs and spices sample after repeated exposure to the three soup variants. The addition of herbs and spices to modified versions of traditional foods could, thus, increase palatability while compensating for reductions in salt [22
], fat, and energy [24
]. Prior work also showed that herbs and spices could be an effective strategy to improve the flavor and increase liking and preference for foods with lower palatability such as vegetables [26
]. Such a strategy is promising but research is still limited. In particular, the effectiveness of herbs and spices to improve overall liking and consumption of legumes remains to be tested.
In addition, there is some evidence that herbs and spices might also play a role in appetite sensations through various potential mechanisms [30
]. For instance, the perceived heat from chili peppers may be linked with increased post-meal satiety (sense of fullness) [33
]. Certain components found in legumes such as protein and fiber might also influence appetite regulation. Kristensen et al. [34
] showed that protein-rich meals based on beans and peas increased satiety more than protein-rich veal and pork-based meals. Meat is among the most popular choices in eating out of home [4
] and, with more and more people choosing to eat away from home [35
], the more traditional “full-service” restaurant sector contributes significantly to the out-of-home dining market [36
]. In this setting, using herbs and spices to enhance liking of legumes while compensating for reduction of salt in a real context ecological restaurant is an area of research that needs further attention.
The aim of this study was to determine whether adding herbs and spices to low-salt legume-based dishes can increase overall liking and preferences of legumes among young adults at a single meal occasion. In addition, the study examined whether the sensory modifications using herbs and spices could influence satiation and food consumption in a real context ecological environment. The hypothesis was that the addition of herbs and spices can enhance the overall liking of low-salt legume-based dishes and increase their intake relative to plain legume-based dishes.
To our knowledge, this is the first study to examine the effectiveness of herbs and spices to improve liking and preference for low-salt legumes conducted in an experimental restaurant setting, a controlled environment relevant to study consumers’ preferences in real-life eating situations. It is among the few studies which used two distinct test paradigms to assess the overall liking of the different versions of the legume-based mezze modified in terms of saltiness and spiciness at different sessions (absolute liking) and during the same session (relative liking). The findings of the present study showed that the standard-salt and low-salt with herbs and spices mezzes were equally liked at both test paradigms. Although there were some differences in the relative overall liking between seasoned and unseasoned mezzes, there were no differences for the absolute overall liking in the cross-over design. This was also reflected in lack of a significant difference in appetite ratings and consumption of mezze or of the entire meal between the four sessions.
To date, a few studies examined the influence of seasoning to increase the liking and consumption of foods with lower palatability such as vegetables, mainly in children or adolescents, with contrasting results [26
]. Fritts et al. (2018) [47
] compared the liking scores of eight seasoned and the equivalent unseasoned (oil and salt) vegetables among 110 high-school students. The seasoning significantly improved the liking and the preference for several vegetables relative to the plain varieties when served at the school lunch. However, in a follow-up short-term study, they failed to show an effect of herbs and spices on increasing the students’ vegetable consumption, although, as the authors suggested, with short repeated exposure, the willingness to consume these flavors might have been increased [26
]. Manero et al. [28
] showed no difference in liking scores between seasoned and steamed versions of vegetables (carrot, broccoli, and green bean) when served as a side dish in a public café on a university campus. In most of the studies, vegetable consumption was measured in an aggregated form; thus, individual intakes could not be tracked.
There is only one published study that looked at the influence of the variety of seasoning in legumes and particularly bean consumption in a population-based case control study of Costa Rican adults [49
]. Findings revealed that increasing the variety of seasoning was associated with bean intake and, thus, a potentially appropriate strategy to improve intake of legumes. Legume incorporation in peoples’ eating plans includes several barriers mainly due to personal taste preferences and lack of recognition and unfamiliarity by consumers [37
]. This led to the creation of the International Year of Pulses campaign in 2016 by the Food and Agriculture Organization of the United Nations [52
]. Legume offerings are minimal in non-ethnic restaurants and account for only 9% of legume intake [53
]. Developing recipes as a spread and offering it as a mezze was a way to increase the feasibility and likelihood that legumes could be broadly adopted to similar eating environments including school and work canteens.
A few studies explored the potential role of culinary herbs and spices and their role as flavor enhancers in low-salt foods [22
]. Contrary to our findings on absolute liking in phase II, Bouhlal et al. [23
] showed a strong preference toward the salted versions relative to unsalted versions of green beans and pasta, with a clear impact of salt content on the intake of those foods. However, as the authors stated, the impact was different for the type of foods with salt reduction, decreasing the intake of green beans by 21%, and addition of salt, increasing intake of pasta by 24%. This perception of saltiness and preference for a salty taste might be food- or product-specific as previously shown [46
]. However, the consumption of pasta did not differ between the 0% and 0.6% added salt variant in children despite the differences in hedonic evaluation between those products, supporting previous findings in adults showing an overestimate of the ideal salt content in foods based only on sensory evaluation [55
]. In our cross-over study, there were no differences in overall appreciation between the low-salt and the standard-salt mezzes, which was accompanied by no differences in food intake. However, in the follow-up assessment, when all the mezzes were presented at the same session, as an indicator of relative liking, both overall appreciation and liking of taste were significantly higher for the standard-salt mezze with added herbs and spices and lower for the low-salt mezze, and no significant difference was found between the low-salt with herbs and spices and the standard-salt mezzes. Those results are partially in agreement with Gwahi et al. [22
], who showed the liking of taste to be significantly lower in the low-salt soup. However, contrary to our findings, which showed that liking was enhanced by incorporating herbs and spices in the low-salt mezze, Gwahi et al. [22
] reported no difference between the low-salt soup and the low-salt soup with added herbs and spices. This could be due to differences in food type and food-specific salty preference as mentioned earlier, or differences in herb and spice modification given that certain herbs and spices contain volatile compounds that could enhance cross-modal saltiness perception [58
Flavor is described as the combination of taste (gustation), smell (olfaction), and chemical burn (trigeminal sensation) [21
]. Using the blend of herbs and spices to enhance the flavor of the mezze stimulated different aspects of the sensory system involved in flavor perception (i.e., salt for gustation, cumin for olfaction, and garlic for the trigeminal sensory system). That could possibly explain why the effect of salt was larger on the liking of taste and why the effect of herbs and spices (1.6 g) was as large as the effect of salt on overall absolute and relative liking [59
]. These results suggest culinary actions to reduce salt content that are acceptable from a catering operator’s point of view, as changing the recipe is possible without lowering consumers’ satisfaction in real-life eating situations. A 50% salt reduction in the mezze recipe with herbs and spices resulted in a 13% reduction in salt for the total test meal, implying that the use of herbs and spices at major eating events, such as lunch and dinner, is a promising approach to reach the WHO target of a relative 30% reduction in salt intake by 2025 [11
Among the strengths of this study was the use of two distinct test paradigms: one for absolute liking and one for relative liking in phase II and phase III, respectively. Different findings were produced in those studies that could be explained by the fact that, in the cross-over study, the one-week washout period might have been effective in blinding participants to the variation of salt and herbs and spices content compared with the side-by-side test of mezzes. In addition, individual differences in experiences and expectations with the test foods with regard to the familiarity of herb and spice blend modification and how the test foods are commonly prepared and consumed could also explain the differences in responses [47
Reducing salt and adding herbs and spices in a typical consumed food, such as a hummus-type mezze in our study, generates a novel stimulus [62
], which increases the unfamiliarity and sensory complexity and could reduce liking relative to the standard version, but for which repeated exposure might increase both familiarity and liking of the reduced-salt version [22
]. Thus, the repeated exposure of the mezzes with similar attributes, except for the salt and herb and spice content, in the cross-over study could have induced a certain degree of familiarity compared with the single exposure. Indeed, introduction of all the test mezzes at the same session could have augmented the perception of the novel modifications. There is some evidence that intake of food can be decreased by repeated exposure to the same food for several days even if the food was initially appreciated [63
]. However, there were no differences in food intake in the current study between the sessions, which could have been due to the balanced randomization and the short exposure course followed in this study.
There were no differences in overall appetite and most of the specific appetite ratings among the four legume-based mezzes. Some limited evidence exists regarding the potential effects of culinary herbs and spices on appetite and food intake regulation, via modulating appetite-related gut hormones and thermogenic effects through sensory stimulation or through the role of their bioactive and flavor compounds on digestive processes [30
]. However, the form (e.g., oral or capsule administration) and the amount of herbs and spices are important factors considering their effect on appetite [32
], with most of the studies providing a dose of herbs and spices much higher (3–20 g) than the amount of herbs and spices in the legume-based mezzes (1.6 g) [30
]. Furthermore, the mezzes were similar in macronutrients, energy, energy density, texture, and legume content, factors that could influence appetite and food intake regulation [66
] and could potentially surpass any impact of spices on appetite through activation of gastrointestinal and chemosensory signals.
A strength of this study is that it was conducted in an ecological environment representing a usual out-of-home eating context. Yet, the lack of controlled experimental conditions for the sensory evaluation and presence of other people in the table should be considered in the interpretation of the results. Another limitation is that the present findings cannot be generalized to other populations and cultures with exposure and preferences to different spices and frequency of legume consumption. Furthermore, this study included measures of reported liking, preferences, and intake of the legume-based mezze served as a starter, a part of a meal typically served in French restaurants, for better understanding of individual variations in eating behavior. However, expectation of the following parts of the meal could have influenced ad libitum food intake of the legume-based mezze with unknown results if the legume test meal would have been served in a different form and as a single main meal. Finally, salt consumption, saltiness sensitivity, and liking of salty foods are linked and impact one another [46
], and, although dietary salt consumption was considered in the analysis, assessment of dietary sodium was based on FFQs, which is prone to underestimation relative to the most reliable 24-h urinary sodium analysis.