Abstract

Brewer’s Spent Grain (BSG) is the primary residue generated during beer production and is nutritionally rich, which makes its reuse in new products an interesting, innovative, and sustainable option. Thus, the present study aimed to characterize cookies developed by partially substituting white wheat flour with BSG at levels of 0%, 50%, and 60%. The cookies were evaluated for their proximate composition, physicochemical properties, and sensory acceptance. The main results obtained were the high content of fiber and protein; the samples containing 50% and 60% bagasse presented, respectively, 9.05 g/100 g and 12.84 g/100 g of fiber, while the protein contents of the 50% and 60% cookies were, respectively, 16.37 g/100 g and 17.06 g/100 g. The samples achieved acceptable sensory ratings, with responses tending toward “slightly liked” and acceptability indices close to or above 70%. Overall, the evaluators preferred the control cookies, while the 50% and 60% BSG cookies did not differ significantly from each other. These findings suggest that incorporating BSG into cookies is a promising option for reusing this commonly discarded residue.

Keywords:Residue; Brewery; Functional foods; Reuse

Introductıon

Currently, there is growing concern regarding the large generation of waste, as it represents one of the main environmental issues both in Brazil and worldwide. This waste generation has intensified primarily due to the expansion of agribusiness and the development of food production processes. In this context, increasing attention is being given to the recycling of agro-industrial by-products and their transformation into high-value new products, thereby achieving the ultimate goal of a “zero waste economy” [1]. The three main concerns involved are reducing waste and losses in the production chain, developing economic alternatives, and reducing food insecurity [2].

Among these residues, Brewer’s Spent Grain (BSG) is noteworthy since it is generated in large quantities throughout the year [3]. BSG is the main by-product resulting from the initial stage of beer production and is generated from the filtration of the wort prior to boiling. Its composition is basically the husk of malted barley, and it represents approximately 85% of the residues generated by breweries, being primarily destined for animal feed [3].

According to the Brazilian Beer Industry Association, national beer production in 2020 reached 14.1 billion liters. In the same year, Brazil recorded 1,383 breweries registered with the Ministry of Agriculture, Livestock, and Supply (MAPA), with 85.6% of these concentrated in the South-Southeast region [4]. The high production of beer consequently leads to an increase in the generation of BSG, with an estimate that every 100 liters of beer produced results in 14 to 20 kg of BSG [5]. A study conducted by Tombini et al. [6] on the management of BSG in breweries located in the western and far western regions of the state of Santa Catarina indicated that, in the vast majority of the interviewed breweries, this residue is donated to cattle producers without any profit margin for the industries.

BSG is considered to be high in protein and dietary fiber, as it contains 18.24 g/100 g and 37.70 g/100 g of these constituents, respectively [7]. In addition, it contains 1.2% mono and dihydroxy phenolic acids and is a source of B-complex vitamins; therefore, it has high nutritional value [5]. This has led to consideration of other ways to reuse this residue besides its use as animal feed, such as enriching foods like cookies to improve consumer health and offer a new product option in the market.

Regulation Resolution No. 263 of September 2005 defines biscuits or cookies as products obtained by mixing flour(s), starch(es) and/or starch derivatives with other ingredients, which are then kneaded and cooked; these products may or may not be leavened and can have various toppings, fillings, shapes, and textures. These products are highly consumed, being present in 99.6% of Brazilian households, with an average consumption of 5,500 kg per person per year [8].

Thus, given the modern food industry’s interest in sustainability and human health and considering that BSG is a significant by-product with a unique composition, this study aimed to develop two cookie formulations enriched with BSG at 50% and 60% levels, in addition to a control formulation (0% BSG), and to evaluate their proximate composition, sensory analysis, and purchase intention.

Materials and Methods

Cookie Preparation

This study is classified as descriptive and experimental [9]. For the current research, different cookie formulations were developed by partially substituting white wheat flour with BSG flour at concentrations of 50% and 60%, in addition to the control formulation (0% substitution). The BSG used for developing the cookies was donated by Dalla Cervejaria, located in Cordilheira Alta (SC), and was obtained from Pilsen-type beer production. For this study, BSG from the same production batch was used and stored in a horizontal freezer (Consul brand, model CHB53EBBNA) at approximately –18 ºC until the cookies were prepared and analyzed. The development of the formulations, as well as the proximate composition and sensory analyses, were performed in the Food Technology, Bromatology, Chemistry, and Sensory Analysis laboratories at the Universidade Comunitária da Região de Chapecó -Unochapecó.

The other ingredients used in the cookie formulations were purchased from a local market in the city of Chapecó/SC and included white wheat flour (Rosa Branca brand), salt (Diana brand), brown sugar (Sulmel brand), granulated sugar (Delta brand), unsalted butter (Gran Mestri brand), vanilla essence (Dr. Oetker brand), Tahiti lemon, 52% cocoa chocolate chips (Melken brand), nutmeg (Apti brand), baking soda (Apti brand), and eggs.

Before being used in the cookie production, the BSG underwent a drying process in a dehydrator (Quimis brand, model Q314M252) at 60 ºC for 24 hours and was subsequently ground in a blender (Philips Walita brand, model Liqfaz) to reduce its particle size, giving it a flour-like consistency and facilitating its homogenization with the other ingredients in the formulation. The dried and ground BSG is shown in (Figure 1).

*51 g 51 g corresponds to one egg. Source: developed by the authors.

The ideal cookie formulation was determined by performing preliminary tests based on a standard formulation, varying ingredient proportions until the optimal combination and quantities were obtained. Based on these tests, partial substitutions of white wheat flour with BSG flour were made, with the 50% and 60% levels receiving the highest sensory acceptance from the research group; thus, the study focused on these percentages. The cookie formulations used are shown in (Table 1).

For cookie preparation, the procedure followed the flowchart in (Figure 2). First, the ingredients were separated and weighed; then, brown sugar, granulated sugar, and butter were homogenized in a mixer (Philco brand, model PBP1200P). Next, the egg, vanilla essence, salt, lemon juice, and nutmeg were added and mixed again in the mixer. Finally, the wheat flour, baking soda, and BSG flour (except in the control formulation) along with the chocolate chips were manually mixed.

Once the dough was ready, the cookies were shaped, placed on baking trays lined with parchment paper, and refrigerated for about 12 minutes. After this period, the cookies were baked in a preheated oven (Fischer brand, model Fischer Grill) at 180 ºC for approximately 15 minutes, removed from the molds after cooling (Figure 3), and submitted to sensory analysis. The remaining cookies were stored in a closed container and kept refrigerated at approximately 20 ºC in a refrigerator (Consul brand, model CRB36AB) until the proximate composition analyses were conducted.

Proximate Composition of the Cookies

The cookies’ characterization was performed through analyses of moisture, ash content, crude protein, lipids, and dietary fiber, with each analysis conducted in triplicate.

Moisture

Moisture analysis was determined using the method described by the Instituto Adolfo Lutz [10]. The gravimetric method was applied, using 5 g of sample heated in an oven (Quimis brand, model Q314M252) at 105 ºC until a constant weight was achieved. The percentage of moisture was obtained by the difference between the weight of the wet sample and that of the dried sample.

Ash

The ash content followed the methodology proposed by AOAC (1995). Ash was determined by incinerating 5 g of sample in a muffle oven (Quimis brand, model Q318S21) at 550 ºC for about 4 hours, until the resulting ash turned white or slightly gray. The ash percentage was calculated based on the difference between the initial sample weight and the weight after muffle processing.

Protein

The crude protein percentage was determined in a thirdparty laboratory (Laboratório de Análises LabCal, Department of Food Science and Technology, Federal University of Santa Catarina - UFSC) by determining the total nitrogen percentage in the samples according to the Microkjeldahl method. The samples were digested, distilled, and titrated following the methodology described in method No. 991.20, in accordance with the Association of Official Analytical Chemists (AOAC, 2019). Protein results were expressed in g/100 g.

Lipids

For the determination of lipid content, the hot extraction method of the Weende procedure was applied as proposed by the provider of the fat determination equipment Goldfish (Tecnal brand, model TE-044-5/50), using petroleum ether (Êxodo Científica brand) as the organic solvent. Prior to the analysis, the reboilers were dried in an oven (Quimis brand, model Q314M252) at 105 ºC for 2 hours. The procedure began by weighing 2.5 g of cookies, which were then placed in filter paper cartridges. The cartridges containing the samples were fixed onto the equipment’s stem. Next, 100 mL of solvent was added to the reboilers, and the cartridges were immersed in the solvent for 1 to 1.5 hours at 90 ºC. After lifting the cartridges for 30 minutes at the same temperature, the equipment was set to 130 ºC to initiate solvent recovery and lipid separation. The solvent was allowed to evaporate for about 2 hours before the equipment was switched off. The reboilers containing the lipids were then placed in an oven (Quimis brand, model Q314M252) at 105 ºC for approximately 2 hours, and finally, they were allowed to cool in a desiccator before weighing and calculating the lipid percentage.

Dietary Fiber

Dietary fiber quantification was conducted in a third-party laboratory (Laboratório de Análises LabCal, Department of Food Science and Technology, UFSC). The method for soluble fiber determination followed AOAC method No. 985.29 (AOAC, 2019), and the method for insoluble fiber determination followed AOAC method No. 991.43 (AOAC, 2019). Results were expressed in g/100 g.

Sensory Analysis and Purchase Intention of the Cookies Sensory Analysis

The study was submitted to and approved by the Committee for Research Ethics in Human Subjects (Protocol No. 43771521.5.0000.0116) of the Universidade Comunitária da Região de Chapecó- Unochapecó.

To evaluate the sensory acceptance of the developed cookies, a sensory analysis was conducted. This was carried out by collecting affective responses from a group of 50 untrained panelists using a 9-point hedonic scale test. Panelists rated how much they liked or disliked each of the three samples (0%, 50%, and 60%) on attributes such as appearance, aroma, flavor, texture, and overall impression (where 1 = “disliked extremely”; 2 = “disliked very much”; 3 = “disliked moderately”; 4 = “disliked slightly”; 5 = “neither liked nor disliked”; 6 = “liked slightly”; 7 = “liked moderately”; 8 = “liked very much”; 9 = “liked extremely”) [11]. The samples were provided in plastic containers coded with random three-digit numbers, along with a cup of water to cleanse the palate between samples.

Furthermore, the profile of the panelists was determined using a standardized questionnaire administered via Google Forms, which gathered sociodemographic data and information on consumption habits.

Purchase Intention

Purchase intention was evaluated by asking the panelists to rate on a 3-point scale whether they would buy the preferred sample, buy all three samples, or not buy any sample. The panelists indicated their choice on the evaluation form [10].

Acceptability Index (AI)

The Acceptability Index (AI) for each cookie formulation was calculated using Equation 1, which establishes the ratio between the mean score and the maximum score given for each attribute on the hedonic scale.

Where:
A = the mean score for each attribute obtained from the hedonic scale for the sample; B = the maximum score given for each attribute.

Preference Analysis

For determining the preferred sample, a paired preference test was conducted according to the methodology proposed by the Instituto Adolfo Lutz [10], whereby each panelist ranked the samples in order of preference.

Statistical Analysis

The results of the sensory evaluation and proximate composition analyses of the cookies were subjected to analysis of variance (ANOVA) using the Statistica 12.0 software (StatSoft®, USA) and the Tukey test at a 5% significance level (p < 0.05), to verify statistical differences among the three samples.

Results and Discussion

Proximate Composition of the Cookies

(Table 2) presents the proximate composition results for the three cookie formulations.

Note: Means followed by the same letters in the same row do not differ significantly according to the Tukey test at a 5% significance level (p < 0.05).
Source: Developed by the authors.

From (Table 2) it can be observed that the average moisture values for the three formulations (0%, 50%, 60%) were 11.83%, 10.89%, and 14.22%, respectively, which are in accordance with ANVISA Resolution No. 263/2005 that establishes a maximum moisture limit of 15% for cereal-based foods. In addition, it is noted that the formulations with 50% and 60% bagasse differed statistically from each other but did not differ from the control formulation.

This increase in moisture content when a higher percentage of BSG is added to the cookies can be explained by the nature of fibers in high-fiber foods, which have the capacity to retain greater amounts of water [12].

Pereira et al. [13] observed that when developing butter cookies with jatobá flour at 40% and 60%, the addition of jatobá flour increased the moisture content compared to using wheat flour alone. Likewise, studies by Queiroz et al. [12] in the production of gluten-free cookies enriched with coconut flour showed that the moisture content increased from 13.23% (0% coconut flour) to 16.23% (5% coconut flour).

The ash content varied from 1.51% to 2.0%, with ash content increasing in proportion to the amount of BSG added, indicating higher concentrations of minerals in the cookies produced with the brewery residue. In the 50% and 60% formulations, the difference in ash content was not statistically significant. Wust [14], while analyzing cookies made with BSG, found ash contents ranging from 0.87% (0% BSG) to 2.09% (100% BSG), in agreement with the results obtained in this work.

Regarding lipid content, the samples did not present significant differences, ranging from 24.47% to 26.73%. Nizer et al. [15] also observed a progressive increase in lipid content when developing cookies by partially substituting wheat flour with a mix of grape bagasse and malt flour (25% and 75%, respectively), yielding lipid contents of 13.37% and 15.53% for the 25% and 50% formulations, respectively.

Ikuomola, Otutu, and Oluniran [16], when developing cookies with a blend of wheat flour and malted barley (Hordeum vulgare) bran, also registered an increase in lipid content as the replacement level increased from 5% to 50%. Although the lipid values were higher than those obtained in this work, the range reported by the authors was between 29.86% and 32.36%. Moreover, the authors stated that the higher lipid content improves product quality in terms of flavor and texture.

When evaluating protein content in the cookies, all three samples (0%, 50%, and 60%) can be considered high-protein, as they exhibited protein contents greater than 12 g/100 g, as established by Brazilian legislation IN No. 75/2020 [17]. It is noteworthy that the formulations differed statistically from each other, suggesting that a higher percentage of BSG flour results in higher protein content, given that this residue is rich in protein [7]. Rigo et al. [18], when producing cookies with BSG flour at 10%, 20%, and 30%, as well as a standard cookie (0%), also observed that increased malt content proportionally elevated protein levels, varying from 11.8% to 15.34%. Similar results were obtained by Sileone [19], who reported that the protein content in butter cookies developed with 30% BSG addition reached 10.27% ± 0.04.

Regarding dietary fiber, the cookie samples showed values varying from 3.19 g/100 g (control) to 12.84 g/100 g (60% sample). The dietary fiber levels in the cookies containing 50% and 60% BSG classify them as high-fiber products according to IN No. 75/2020 [17], since the values found exceeded 6 g of dietary fiber per 100 g of sample.

Tombini et al. [20] incorporated BSG in cereal bars and evidenced high dietary fiber content, with the formulation containing 24% BSG presenting 8.43 ± 0.25 g/100 g of fiber. According to Ikuomola, Otutu, and Oluniran [16], the higher fiber content observed in the 50% and 60% BSG cookies can be explained by the fact that malt contains a relatively higher fiber content than wheat. The authors further asserted that the presence of high fiber content in food products is essential due to its ability to facilitate intestinal movement, add bulk to foods, and help prevent various gastrointestinal diseases. Rigo et al. [18] additionally mentioned that the addition of fiber to cookies contributes to a reduction in caloric content.

Sensory Analysis of the Cookies

The sensory analysis involved 50 untrained panelists, who evaluated the 50% and 60% BSG cookie formulations as well as the standard formulation (0% BSG).

To determine the profile of the panelists, a questionnaire was administered, revealing that the majority of participants were female (72%). Regarding age, the largest group was between 21 and 25 years old (36% of the panelists), followed by the 26-35 age group (32%). When asked if they had the habit of consuming healthy foods and whole grains such as oats, flaxseed, brown rice, chia, etc., 94% and 82% of the panelists, respectively, answered affirmatively; and in terms of consumption frequency, 10% reported consuming whole grains daily, 50% from one to three times per week, 8% less than once a month, and 4% stated they do not consume whole grains.

Regarding the consumption of cookie-type biscuits, 92% of the participants reported that they consume these products, with 52% liking them moderately, 36% liking them very much, and 10% remaining indifferent. Furthermore, 66% indicated that cookies are primarily consumed as an afternoon snack, followed by 12% at breakfast; the highest frequency was reported by 54% of the panelists who consume cookies one to two times per month, followed by 36% who consume them less than once per month.

Moreover, when purchasing cookie-type biscuits, 72% of the panelists opted for traditional cookies, while only 24% chose whole grain cookies. The most motivating factor for purchase was flavor (cited by 50% of the panelists), followed by the characteristic of being a healthy product (22% of the panelists). In addition, 54% of the panelists stated that they examine the nutritional information on the cookie packaging, and the same percentage affirmed that they consider the ingredients used in the production process (for example, the use of brown sugar instead of white sugar). When asked what aspect of the cookie packaging, they pay the most attention to, 30% mentioned the list of ingredients, followed by 12% who examined the fiber content, another 12% the energy value, 6% the fat content, and 4% the sodium content; the remaining percentage did not evaluate the packaging.

Using the 9-point hedonic scale, the sensory analysis results presented in (Table 3) showed that for all evaluated attributes, the mean scores were equal to or greater than 6 (“liked slightly”). The attributes that received the highest evaluations from the panelists were flavor and aroma in all cookie samples.

Note: Means followed by the same letters in the same row do not differ significantly according to the Tukey test at a 5% significance level (p < 0.05).
Source: Developed by the authors.

Table 3 clearly indicates that attributes such as color, appearance, and texture received the lowest mean scores, which decreased gradually with the increase in BSG percentage. The lower scores for texture and appearance can be explained by the more fibrous appearance resulting from the higher concentration of malt-and consequently fiber-when comparing the 60% cookies with the control (0% BSG) cookies.

Rigo et al. [18], when conducting a sensory evaluation of cookie attributes (appearance, color, texture, aroma, flavor, and overall acceptance) in cookies made with BSG flour at 10%, 20%, and 30% levels as well as a standard sample (0%), obtained positive results; their formulations had mean scores above 7.0, corresponding to “liked moderately” on the 9-point hedonic scale. In addition, cookies made with 10% and 20% BSG flour were more accepted than the standard formulation, indicating the viability of partial wheat flour replacement with BSG. Ferreira’s (2017) study on whole-grain cookies using BSG at 0%, 10%, 30%, and 50% yielded similar results for texture (6.86 to 7.49) and flavor (7.42 to 7.76).

Concerning the dark brown coloration of samples with increased levels of BSG substitution, Ikuomola, Otutu, and Oluniran [16] stated that darker colors may be caused by nutrient interactions during processing and the combined effects of temperature and cooking time. Moreover, Wust [14] noted that darker coloration with the addition of malt flour is characteristic of high-fiber products, which may be associated with the lower scores assigned to BSG cookies compared to the control cookies.

Purchase Intention of the Cookies

Figure 4 shows the purchase intention percentages for the evaluated cookies. It was observed that the control cookies had a more positive purchase intention than the BSG cookies, with 54% indicating “I would definitely buy this product.” However, the 50% BSG cookies recorded the highest frequency (42%) for the response “I am not sure if I would buy this product.”

Acceptability Index (AI)

Glüger and Gurak [8] established that for a product to be well accepted in its sensory attributes, the Acceptability Index (AI) should be equal to or greater than 70%. The AI values obtained are presented in (Table 4).

Source: Developed by the authors.

Based on the decision criterion of an AI equal to or above 70%, the aroma attribute achieved the highest acceptance in all formulations, exceeding 80%. The sample with 50% BSG had higher acceptability compared to the 60% sample, while the control cookies showed the highest acceptability indices in the sensory analysis. The BSG-containing samples had appearance scores very close to 70%, with all other attributes above that value.

Glüger and Gurak [8], in their evaluation of savory cookies developed with BSG flour, obtained similar acceptability indices, noting that the formulation with 25% BSG flour had higher acceptance compared to the 50% formulation, with an acceptability index over 70%. Similarly, Panzarini et al. [21] in their sensory analysis of honey cake enriched with 7% and 10.5% BSG (replacing wheat flour) found acceptability indices exceeding 80% for both formulations [22].

Preference Analysis

The results of the preference analysis, as shown in (Table 5), indicate that among the three cookie samples, the control sample (0% BSG) was the most preferred by the panelists, [23-24] while the 50% and 60% BSG cookies did not differ significantly from each other.

Note: Means followed by the same letters in the same row do not differ significantly at a 5% significance level (p < 0.05). Source: Developed by the authors.

Conclusion

From the study, it can be inferred that within the evaluated proximate parameters, the fiber and protein contents were the most notable. The cookies with 50% and 60% BSG presented fiber levels of 9.05 g/100 g and 12.84 g/100 g, respectively, classifying them as high in dietary fiber according to the legislation. In terms of protein content, the cookies were considered high-protein, with values exceeding 12 g/100 g, as established by Brazilian regulations.

The sensory analysis of the developed cookies yielded mean scores equal to or above 6 (“liked slightly”), with the flavor and aroma attributes receiving the highest scores among the three formulations. Overall, the control sample (0% BSG) achieved the best scores in all attributes, with statistically significant differences observed only for the color and appearance attributes, where the control sample had superior acceptability. It is noteworthy that the cookie containing 50% BSG flour obtained a higher acceptability index than the 60% sample for all evaluated attributes, although the control sample still had the highest indices overall.

Regarding purchase intention, the most positive result was observed for the control cookies, with 54% of respondents indicating “I would definitely buy this product.” However, the 50% BSG cookies elicited the highest proportion (42%) for the response “I am not sure if I would buy this product.” Overall, the panelists preferred the control cookie sample, while the 50% and 60% samples did not show statistically significant differences in this regard.

Possibly due to differences in texture, appearance, and color compared to commercially available cookies-stemming from their high protein and fiber content-the BSG cookies experienced higher rejection compared to the control sample. However, the possibility of using BSG from breweries to produce a new product is not ruled out, as it not only adds nutritional value to the food but also contributes to environmental preservation by reusing a residue that was previously discarded or used only as animal feed.

Acknowledgment

The authors would like to acknowledge the Universidade Comunitária da Região de Chapecó -Unochapecó, the Scientific Initiation Scholarship Program (PIBIC/CNPq), the Santa Catarina University Scholarship Program (UNIEDU), the Research Support Foundation of the State of Santa Catarina (Fapesc), and Dalla Cervejaria in Cordilheira Alta/SC for donating the BSG used in this study.

• Research Article
• Abstract
• Introductıon
• Materials and Methods
• Results and Discussion
• Conclusion
• Acknowledgment
• References