Wheat bran is a by-product produced during the dry milling of (Triticum aestivum L.) wheat into flour. It is an economical ingredient with several health benefits, but its use in the human diet is limited because of its digestion and absorption difficulties, flavor and appearance. However an appropriate amount of fiber is good for intestinal health. Wheat grain comprises 14.5–25% bran (Das Neves et al., 2006; Xie et al., 2008), but only 10% of it is used in cereals and baked items as a source of dietary fiber (Rahman et al., 2017). While 90% of bran, is wasted by millers because of its high transportation expenses (Rahman et al., 2017), used as animal feed or for biocomposite production in the biomedical industry (Dungani et al., 2016).

People consider it inappropriate to include it in their diet because of its indigestion qualities (Sozer et al., 2014), taste and appearance differences (Heiniö et al., 2016; Stanyon and Costello, 1990). Sozer et al. (2014) found that addition of wheat bran reduced contents of digestable starch in biscuits. Heiniö et al. (2016) found that the addition of wheat bran darkened the color and increased bitterness in cereal foods.

However, the micronized form of bran is considered suitable for consumption in the human diet. Research shows that micronized bran could be used as a food ingredient, and its addition to food could improve the nutritional potential of food products (Hemery et al., 2011). The role and use of agriculture by-products are gaining popularity because of their contribution to food sustainability. Approximately 14 % of the world’s food is wasted annually from harvest to retail market (FAO, 2019), and 17 % of food is wasted at retail and consumption levels (UNEP, 2021). The highest food loss (approximately 21%) occurs in Central and South Asia (FAO, 2019).

Natural disasters, production losses and personal preferences are among the factors which cause food losses and wastage. For example, fruit by products such as peels, trimmings, bagasse, bran, seeds, stems and shells account for more than 50% of fresh fruits (Ayala-Zavala et al., 2011). A fifth part of edible food such as food by-product is wasted due to its surface blemishes, unique coloration and unfamiliar shapes.

Therefore, food scientists and researchers are working hard to find its suitability for the human diet. Number of studies have been carried out to determine its suitability for the human diet (Gómez et al., 2011; Lee et al., 2010; García et al., 2002; Zhang and Moore, 1997). Apart from suitability, commercialization of by-products is also under consideration. A number of studies are being carried out to understand how to commercialize these food products successfully because food products prepared from food by-products exhibit low sensory qualities (Gómez et al., 2011; Singh et al., 2012; Zhang and Moore, 1999).

Literature confirms that effective marketing communication could enhance the acceptance of upcycled products (Ghazanfar et al., 2022; Zhang et al., 2021; Bhatt et al., 2020). The effects of both intrinsic and extrinsic properties in the acceptance of food by-products are under investigation. Few studies have investigated the role of extrinsic properties (message) in food by-product acceptance as an ingredient. Literature shows that health (Fernqvist and Ekelund, 2014; Mora et al., 2020), organic (Ekelund et al., 2007), local (Januszewska et al., 2013), and environmental claims (Henchion et al., 2016) could enhance acceptance of upcycled products.

Environmental claims are widely studied to assess the acceptance and willingness to pay for upcycled food (Ammann et al., 2024; Giezenaar et al., 2024; Ghazanfar et al., 2022; Henchion et al., 2016; Bhatt et al., 2020). However, the impact of environmental claims on sensory perceptions and investigated the impact of sustainability claims on consumers’ sensory perceptions or emotions. Giannoutsos et al. (2023) studied the effect of sustainable sensory packaging on sensory perceptions of rusk, and they found sensory perceptions of rusk were heavily driven by positive emotions due to sustainable packaging. Ford et al. (2024) studied the effect of environmental information on consumer liking and emotional responses toward conventional and hypothetical precision fermented yoghurt, and found that environmental information slightly improves liking and emotional responses for precision fermented yoghurt however decrease liking for conventional yogurt.

Mora et al. (2020) studied the impact of sustainability, local, and health claims on dip sauce liking (i.e., color, taste, density, and flavor) prepared from vegetables by-products. However their results showed that sensory perceptions were not affected by the sustainability claim. Similarly Erhard et al. (2024) found that sustainability claim adversely affects the taste perceptions of consumers seeking hedonic benefits from food.

However, these few studies are not enough to conclude the role of sustainability claims in shaping or enhancing sensory perceptions and emotions. Mora et al. (2020) made a dip from vegetable by-products and tagged it with “made using food by-products,” and asked respondents to evaluate its sensory characteristics after tasting it. Mora et al. (2020) found the insignificant effect of the sustainability message.

This study hypothesize that the presentation of the message plays an important role in the persuasiveness of the message. Literature suggests that an appropriate message focusing on the product could enhance new product acceptance (Krishnan and Jain, 2006). Presenting a message by creating the right appeal could enhance the effectiveness of the message. The nature of the appeal used to deliver messages could play an essential role in improving the effectiveness of persuasion attempts. Copeland (1924) proposed that consumers often purchase products for two reasons—rational or emotional. Marketing communication aligned with consumer purchasing goals could enhance communication effectiveness. Therefore, this research aims to analyze the effects of the two sustainability appeals (rational and emotional) on consumers’ sensorial liking (taste, color, and aroma) and emotions toward “Roti” prepared from wheat bran.

Rational appeal provides consumers with logical arguments, why product is valuable to them. Emotional appeal stimulates negative or positive feelings associated with the product or supports a cause to influence consumer purchase decisions (Armstrong et al., 2014). Designing the right appeal is essential for sensory and emotional acceptance of upcycled products because food prepared from by-products exhibits low sensory qualities (Gómez et al., 2011; Singh et al., 2012; Zhang and Moore, 1999). Weak sensory characteristics might restrict the use of by-products in the human diet. However, sustainability claims could affect consumer sensory perceptions and emotions (Giannoutsos et al., 2023). Both rational and emotional appeals have been widely used by researchers and marketers to increase product acceptability. A number of studies have drawn comparisons to understand their effectiveness. The literature shows that rational appeal develops a positive product attitude than emotional appeal (Heath et al., 2009; Rizwan et al., 2013). However, literature also supports that emotional appeals evoke favorable emotions; consumer associates these emotions with the advertised product, and this association helps to enhance product acceptance (Metha and Purvis, 2006; Yoo and Deborah, 2005).

However, creating a suitable appeal to promote sustainability is under investigation. To the best of our knowledge, only Bhatt et al. (2020) tested the effects of emotional and rational sustainability appeals on willingness to pay for food prepared from food by-products. Their results showed that rational appeal is more effective in increasing willingness to pay than emotional appeal. However, their research was on visual stimuli and they did not study the effects of sustainability appeals on consumer sensory perceptions. Testing of a real stimulus in food is better to understand consumer acceptance.

The literature also confirms that upcycled food lacks sensory qualities. So, the analysis of the effects of the using different sustainability appeals could lead to a better understanding of upcycled food acceptance and willingness to pay.

To the best of our knowledge, no research study has investigated how these two different sustainability appeals affect sensory perceptions and emotions toward food prepared from food by-products.

Therefore, the present research study will investigate the influence of two different appeals, i.e., emotional and rational sustainability appeals on sensory perceptions and emotions for traditional product “roti.”

Traditional products could be more vulnerable to ingredient change. Kühne et al. (2010) suggested “preservation of the traditional state” of the food as a “prerequisite” for innovation in traditional food recipes and products. However, sustainability claims could help to overcome consumers’ reservations about change. Giannoutsos et al. (2023) found that information about sustainable packaging affects food acceptance and emotional responses toward traditional Greek rusks (paximathi). Roti (chapati) is a flat round bread, used as a staple food in the Indian subcontinent. It is popular in many South Asian countries including Pakistan, India, Singapore, Sri Lanka, Bangladesh, Nepal, Thailand, Maldives, Jamaica, Myanmar, Indonesia, Malaysia, and many more. It is made from a combination of water and wheat flour, which are combined to make dough (Haridas Rao and Sai Manohar, 2003). However, wheat production is not sufficient to meet the daily demand of South Asian people, whose staple food is roti. In South Asian countries, wheat is the main component of the milling and baking industries.

The increase in population and natural disasters has badly affected wheat production, which fails to meet dietary needs. Bran can substitute a proportion of wheat in roti making. Bran is an economic agriculture by-product with multiple nutritional values, i.e., proteins, fats, carbohydrates, minerals, vitamins, antioxidants, and phenolic compounds. The use of bran in daily diet may help to maintain the performance of the gut, prolong satiety, and regulate appetite (Wang et al., 2023).

However, its replacement as a proportion of wheat flour in roti might disturb its sensory characteristics. Literature confirms that consumers reject new food products that they recognize to be unpalatable, regardless of health claims (Lyly et al., 2007).

So, the objectives of this study are to investigate the effects of two different sustainability appeals, i.e., emotional and rational appeals on consumer sensory perceptions and emotional responses toward different samples of roti prepared from various wheat and bran proportions.

Food wastage and shortage issues are getting worse day by day (Lipinski et al., 2016; Hegnsholt et al., 2018; Gunders, 2012). Agriculture by-products provide a promising solution by handling the issue close to the source of food waste (Bhatt et al., 2018). Despite the benefits, consumer avoids it because of its low sensory properties. Literature supports that sustainability claims could enhance willingness to pay for upcycled food. However, no research has conducted to analyze how sustainability appeals effect sensory perceptions and emotions. So, this research study aimed to fill this gap.

The results of the sensory evaluation revealed that sustainability appeals had positive effects on the sensory perception of 10–90% and 20–80% bran-wheat roti samples. The results confirmed that sustainability appeals played a successful role in improving the sensory perceptions of consumers and triggering their positive emotions toward upcycled food. The results are in line with the results of Giannoutsos et al. (2023), who found that sustainable packaging information had a positive impact on the sensory profile of the product.

Results further revealed that rational sustainability appeal had higher sensory liking scores than emotional sustainability appeal. The findings are in line with the results of Bhatt et al. (2020), who found rational sustainability appeal more effective in enhancing acceptance of upcycled food than emotional sustainability appeal. Now, consumers have started to focus on the sustainability of the environment and agriculture. Consumers have started developing concerns about food shortages and future needs. Natural disasters, wars, and food processing practices are contributing to food loss and shortage. Our results support that appropriate communication highlighting food loss and its effect on generations could affect acceptance of upcycled food. The results of our study are also supported by the findings of Eagly and Chaiken (1984), who found cognitive appeals more effective for persuasion.

However, for the 30–70% bran-wheat roti sample, results revealed that sustainability appeal had failed to affect the sensory perceptions of consumers; the results are in line with Mora et al. (2020), who found the insignificant effect of sustainability claim on the sensory perceptions of consumers toward dip sauce made vegetables by-product. The differences found in taste and texture; unacceptable (bitter; found during conversation section) taste and granular texture than usual wheat roti made it strange for respondents. Sustainability appeals might fail to have significant effects due to these major differences in sensory attributes. Literature also supports our results by confirming that sensory properties have more influence on developing food liking and choices than extrinsic properties (message) (Mora et al., 2020; Janssen and Hamm, 2012; Vázquez-Araújo et al., 2012). Flour replaced by 20% of bran does not disturb food process ability, quality, and acceptability (Singh et al., 2012). However up to 20% may affect sensory characteristics of food, and any addition that makes it unpalatable decreases the chances of consumer acceptance (Kühne et al., 2010).

In addition, the results of our study could be associated with the product category: traditional or innovative. Roti is a traditional staple food of Pakistan, eaten three times a day. Being traditional staple food, respondents might have given more importance to hedonic benefits than the extrinsic properties (messages associated with each sample). Wheat flour replaced by 30% bran produced great differences in the sensory quality of roti, which might have made it unacceptable for respondents even after the sustainability appeal. Our findings are in line with the results of Kühne et al. (2010), who suggested preserving the traditional state of the food as prerequisite for innovation in traditional food recipes and products. Similar results were found by Lyly et al. (2007), who found a decline in consumers’ willingness to pay for beverages and soups after the addition of β-glucan and even health claims failed to attract consumers.

The research also studies the emotions evoked by two different sustainability appeals. The results show that sustainability appeals evoked positive product emotions; our findings are in line with the results of Giannoutsos et al. (2023). Rational and emotional sustainability appeals evoked positive emotions. However, rational sustainability appeal evoked more positive emotions with greater frequency than emotional sustainability appeal.

Food wastage and shortage issues are getting worse day by day (Lipinski et al., 2016; Hegnsholt et al., 2018; Gunders, 2012). Agriculture by-products provide a promising solution by handling the issue close to the source of food waste (Bhatt et al., 2018). Despite the benefits, consumer avoids it because of its low sensory properties. However the results of our study prove that sustainability claims could enhance sensory perceptions and evoke positive emotions toward food prepared from food by-products. The results of this study confirmed that sustainability appeals played a successful role in improving the sensory perceptions of consumers and triggering their positive emotions toward upcycled food.

However, any addition to food that makes it unpalatable decreases the effectiveness of sustainability appeal. Results further show that rational appeal is more effective in promoting sustainability, enhancing sensory perceptions and inciting positive emotions than emotional appeal.

Although upcycling of food is not common in the world, however (developing) countries like Pakistan must promote the upcycling of food. The agriculture system of Pakistan is not enough to support the population of 240 million. Pakistan’s agriculture sector is more vulnerable to natural disasters as it lacks basic infrastructure such as dams or canal systems to support agricultural needs. In this scenario, upcycling is the need of the hour. Marketers should use suitable marketing communication tools to highlight the importance of upcycling to feed future generations. For instance, rational sustainability appeals could help to realize the impact of food wastage and food losses on current and future generations. This realization might help in accepting upcycled food.

As we focused on only two message appeals, future studies could test the effectiveness of other message appeals. Similarly, this study experimented on a traditional staple food; future studies could consider other food categories, novel foods, and unfamiliar tastes to test the effectiveness of different message appeals.

In Experiment 2, the major representatives of the sample were men, so future research studies may focus on females or draw a comparison between genders.