RECyT

Year 26 / N° 42 / 2024 /

DOI: https://doi.org/10.36995/j.recyt.2024.42.006

Production and evaluation of physicochemical and sensory quality of a liqueur combining orange-fleshed sweet potato and lemon balm

Producción y evaluación de la calidad fisicoquímica y sensorial de un licor combinado pulpa de batata anaranjada y melisa

Enoque Bene F., Moiane¹; Marta Chico, Cumba¹; Abel Alberto, Massingue Júnior^{1, *}; António Elísio, José¹; José Sarmento, Bunga¹; Domingos Afonso, Domingos¹; Ivans Elton, Namacatipa¹; Raimundo Rafael, Gamela¹; Angélica Agostinho, Machalela¹

1- Department of Food Processing Engineering, Higher Polytechnic Institute of Gaza, Agriculture Division, Mozambique.

*E-mail: abelmassingue7@gmail.com

Received: 21/03/2024; Accepted: 02/09/2024

Abstract

Liqueur is a spirit drink resulting from a mixture of ethyl alcohol of agricultural origin and/or brandy, drinking water, sugar and possibly other foodstuffs, with a sweet taste and flavored by maceration of vegetable substances or by distillation of the same substances or by the addition of flavorings. The aim of this study was to assess the physicochemical and sensory quality of a combined orange-fleshed sweet potato and lemon balm liqueur. Four formulations were produced: (A) 30% water, 15% sweet potato and 2% lemon balm; (B) 35 % water, 10% sweet potato and 1.5 % lemon balm; (C) 45% water, 5% sweet potato and 1% lemon balm; and (D) 47% water, without sweet potato and lemon balm; all of which contained 45% alcohol (purchased from the local market and redistilled in the laboratory) and 8 % sugar, were produced and characterized in terms of pH by potentiometry, titratable acidity by titration, total soluble solids content (ºBrix) by refraction, alcoholic strength by alcoholmeter and sensory value using affective methods. The results showed pH ranging from 5.43 to 6.51, titratable acidity from 2.26 to 12.66%, total soluble solids around 17.76±0.15 to 26.20±0.1 ºBrix and alcohol content from 12.60 to 21.30 %v/v. Significant differences were found in pH, titratable acidity, total soluble solids content and alcoholic strength. Sensorially, the acceptability index of the liquor formulations produced indicated that the best formulation was B, with acceptability of 71.14%, and 25% of the tasters stated that they would buy it. The orange-fleshed sweet potato combined with lemon balm is an alternative for making liqueurs and could contribute to product diversification.

Keywords: Liqueur; Ipomeia batata; Lemon balm; Physicochemical and Sensory quality.

Resumen

El licor es una bebida espirituosa resultante de una mezcla de alcohol etílico de origen agrícola y/o aguardiente, agua potable, azúcar y eventualmente otros productos alimenticios, de sabor dulce y aromatizado por maceración de sustancias vegetales o por destilación de las mismas sustancias o por adición de aromas. El objetivo de este estudio era evaluar la calidad fisicoquímica y sensorial de un licor combinado de pulpa de batata naranja y melisa. Se elaboraron 4 formulaciones: (A) 30% de agua, 15% de boniato y 2% de melisa; (B) 35% de agua, 10% de boniato y 1.5% de melisa; (C) 45% de agua, 5% de batata y 1% de melisa; y (D) 47% de agua, sin batata ni melisa; todas ellas contenían 45 % de alcohol (adquirido en el mercado local y redestilado en el laboratorio) y 8% de azúcar, se elaboraron y caracterizaron en términos de pH por potenciometría, acidez titulable por titulación, contenido total de sólidos solubles (ºBrix) por refracción, grado alcohólico por alcoholímetro y valor sensorial mediante métodos afectivos. La caracterización fisicoquímica mostró un pH entre 5,43 y 6,51, acidez titulable entre 2,26 y 12,66%, con sólidos solubles totales entre 17,76 y 26,20 ºBrix y un grado alcohólico entre 12,60 y 21,30 %v/v. Se encontraron diferencias significativas en el pH, la acidez titulable, el contenido total de sólidos solubles y el contenido de alcohol. Sensorialmente, el índice de aceptabilidad de las formulaciones de licores producidas indicó que la mejor formulación fue B (71,14%), con un 25% de los catadores manifestando que lo compraría. El boniato de pulpa anaranjada combinado con melisa es una alternativa para la elaboración de licores y podría contribuir a la diversificación de productos.

Palabras clave: Licor; Ipomoea batatas; Melisa; Calidad fisicoquímica y Sensorial.

Introduction

Sweet potato (Ipomoea batatas (L.) Lam) is one of the main tuber crops grown all over the world, mainly in developing countries such as sub-Saharan Africa, Asia and Pacific Islands. This tuberous root, has carbohydrates as its main macronutrient, this tuberous is low in protein content. Highlight is rich in dietary fiber and vitamin A, has a significant amount of minerals, high glycemic index making it a healthy food (Neunfeld, 2019).

The main characteristic of sweet potato is that it is a highly energetic food, rich in carbohydrates (over 30 % on average in fresh mass) and a good source of vitamins, mainly A, B₆ and C. In addition, orange-fleshed varieties are excellent sources of carotenoids and minerals such as Fe, Ca and K (José, 2016). In Africa it is, according to Shonga et al. (2013), grown predominantly on small plots by subsistence farmers. According to Khalid et al. (2013), the nutritional properties of sweet potato leaves indicate that they have the potential to improve dietary protein and supplement amino acids in a low-fiber diet for ruminants, therefore sweet potato leaves can be used as a protein-rich ingredient for them.

Melissa officinalis (L.) is used in teas, macerates or alcoholic extracts because of its pharmacological properties due to its active constituents. The main interest in medicinal plants, which does not exclude lemon balm, is the active principles, which are products of secondary metabolism, consisting of various groups: mucilages, essential oils, alkaloids, tannins, bioflavonoids, glycosides, organic acids, anthraquinones, phenolic and inorganic compounds and coumarins (Shakeri et al.,2016). The following chemical components are found in M. officinalis leaves: rosmarinic acid, phenolic acid, flavonol, triterpene, gallic acid, geranial, neral, catechin, luteolin, hesperidin, ursolic acid, oleanolic acid, citronellal, citral, β-caryophyllene, germancrene D, ocimene and citronellol. M. officinalis also contain glucose, vitamins E and C, which have significant free radical inactivating activity (Dias et al., 2012).

Due to need to improve artisanal production based on the gradual increase in consumption of drinks specifically liqueurs, consumers are looking for products with better sensory characteristics (flavor). In order to promote the consumption of sweet potato through the development of new products (liqueur) and to improve the way as this product is consumed within communities and promote variety of liqueur on the market. The present study proposes to produce a liqueur combining orange- fleshed sweet potato and lemon balm and to evaluate its physico-chemical and sensory characteristics.

Materials and methods

Raw materials

Orange-fleshed sweet potato (5.0 kg) and white sugar (1.0 kg) were purchased from the Chókwè Central Market. When purchasing the sweet potatoes, the sensory characteristics appearance, color, texture and "Someia" variety were taken into account. Alcohol (1320 mL) was collected from local artisan producers and taken to the laboratory for further redistillation.

Liqueur production

The liqueur formulations are shown in Table 1. For the standard treatment, sweet potato pulp and lemon balm were not incorporated and the others corresponded to 1; 1.5 and 2 % of lemon balm. The liqueurs were prepared according to Figure 1.

Figure 1: Liquor production flowchart.

Sorting and washing. The sweet potatoes were selected using the characteristics described in 2.2. They were then subjected to three stages of hygiene and sanitization: (i) washing with running water, (ii) sanitizing with a 10ppm sodium hypochlorite solution for 10 minutes and (iii) rinsing with running water to better remove the impurities contained.

Peeling, cutting and cooking. The peel was removed with a knife. They were then cut into cubes and immersed in water to prevent oxidization. They were cooked in an aluminum pan for 5 minutes, after which they were left at room temperature (24±2 ºC).

Maceration and filtration. Maceration consisted of extracting substances such as color, aroma and flavor from orange- fleshed sweet potatoes and lemon balm through contact with alcohol for 7 days, thus obtaining an alcoholic extract. Slices of sweet potato were immersed in alcohol at a ratio of 50, 100 and 150g of sweet potato to 450 mL of alcohol, respectively. The solution was then filtered using a 150mesh sieve and placed in glass bottles (750 mL) that had been sterilized at 100ºC and left in a cool, dark place for 7 days.

Preparing the syrup. The syrup was obtained by mixing sugar and water in proportions of 8/30; 8/35; 8/41 and 8/47 g/mL. They were homogenized in a saucepan and placed on a low heat for 10 minutes to dissolve completely. The syrup was then left to cool so that when it was mixed with the alcoholic extract, the temperature of the mixture would not rise and the alcohol would consequently be lost through evaporation.

Mixing. The mixtures were made in the proportions presented in Table 1. All formulations contained 45% alcohol and 8% sugar, were constantly stirred and then left to stand at room temperature.

Bottling and packaging. The final product was placed in 750 mL glass containers and stored at room temperature. The liqueurs were stored in a dark place so as not to let light in, as it changes the color and flavor of the drink.

Table 1: Formulations of the combined orange-fleshed sweet potato and lemon balm liqueur.

	Formulations
Ingredients (%)	A	B	C	D
Alcohol	45	45	45	45
Sugar	8	8	8	8
Water	30	35.5	41	47
Sweet potato pulp	15	10	5	0
Lemon balm	2	1.5	1	0

Physicochemical analysis

Quality parameters were evaluated in terms of hydrogen potential (pH), titratable acidity, total soluble solids content and alcohol content, according to the methods proposed by Adolfo Lutz Institute (2008). All the assays were performed in triplicate.

Sensory analysis

The liqueur was sensorially evaluated by a panel made up of 70 untrained tasters, selected from among the teachers, students and CTAs of the Higher Polytechnic Institute of Gaza, using a sensory evaluation form with a structured nine-point hedonic scale, with scores ranging from 1 (extremely dislike) to 9 (extremely like). Each taster was served a 30 mL sample of each treatment monadically at a temperature of 8ºC to accentuate the creaminess and smoothness of flavor. in disposable cups in a Completely Casualized Design (DBC). All the tasters received the tested samples at once, evaluating attributes such as appearance, color, texture, odor, taste, aroma, aftertaste and overall impression. The acceptance index was calculated according to Equation (1).

Where A, Average score obtained for the product; B, Maximum score given to the product.

Statistical analysis

The data were subjected to analysis of variance (ANOVA) using the general linear model (GLM). When significant effects were detected among the means of the experimental units, they were evaluated using Tukey test at a significance level of 5%, with the RStudio 4.2.1 statistical package (The R Foundation for Statistical Computing).

Results and discussion

Physicochemical characterization of liquors

Table 2 shows the results of physicochemical characteristics of liqueurs A, B, C, D. The results showed pH ranging from 5.43 to 6.51 (Table 2). The highest pH value was observed in treatment A and the lowest result was for treatment D. Significant differences (p <0.05) in the pH were observed in all treatments. This finding may be correlated with the dissolution of organic acids during the alcoholic fermentation process.

Similar results were described by Almeida (2018) who studied the development of guava liqueur and obtained a pH of 4.15. in other study, Silva (2019) made pine cone liqueur with a pH of 5.67. Finally, Castro (2021) made the physicochemical characterization of artisanal pitaya (polyrhizus) liqueur and obtained a pH of 5.84.

Lower pH values were reported in other studies. Magalhães et al. (2014), Teixeira et al. (2005), Silva (2022) and Anjos et al. (2021) prepared different kind of liqueurs with passion fruit, albedo, banana, umbu and strawberry. Lower pH values may be due to the concentrations of brandy and sugar incorporated to the liquor preparation.

The total titratable acidity ranged from 2.26 to 12.66%, from treatment A to treatment D respectively. The analysis of variance shows significant differences between treatments (p <0.05). This phenomenon can be associated with the contact area of pulp and alcohol, facilitating the acids dissolution. This fact can promote an increase in acidity with resulting lowers pH.

Lower acidity values (0.6 - 1.2 %) were reported by Silva (2022) who carried out the production and the physicochemical and sensory evaluation of umbu liqueur (Spondias tuberosa Arruda). Almeida and Gherardi (2018) found an acidity percentage around 0.38 - 0.47% when using guava in the production of liqueur. Silva (2019) produced a pineapple liqueur and obtained acidity values of 0.90%. Nogueira and Venturini Filho (2005) obtained acidity values of 0.20 - 0.28% in graviola liqueur. Mejía-Gutiérrez et al. (2015) obtained an acidity value of 0.75% when producing a blackberry liqueur with 25% pulp. Anjos et al. (2021) found acidity values ranging from 0.140 to 0.330% when studying the physicochemical characteristics of the passion fruit pulp.

Higher results were reported by Dias et al. (2011), who studied the physicochemical and sensory characterization of yellow passion fruit liqueur and obtained an acidity value of 13.1%.

The averages of the total soluble solids content showed that treatment B had the highest total soluble solids content at around 26.20 ºBrix, followed by A with 24.30 ºBrix. The lowest (17 ºBrix) was observed in treatments C and D. Significant differences (p <0.05) in the total soluble solids content were observed between treatments A and B. The differences observed in the formulations produced correlate with the different concentrations of sugar added (8%), or the ability to maintain the °Brix levels due to the reactions resulting in the product, as well as the quantity and absence of sweet potato, resulting in a reduction in the soluble solids content.

Higher results (27 to 48 ºBrix) were reported by Moraes (2018) when looking to produce blackberry liqueur, obtaining total soluble solids values in the range of 27 to 32º Brix. Nascimento (2017) obtained soluble solids ranging from 40.33 to 41.23 °Brix when formulating a banana liqueur with different concentrations of cinnamon. Araújo et al. (2016) obtained soluble solids around 45.8 ºBrix when developing passion fruit liqueur. Viera et al. (2010) obtained soluble solids varying between 27 and 33 ºBrix when carrying out their study on passion fruit liqueurs. These results can be explained by the gas exchange between the liqueurs and the environment, so the solids in the liqueurs were concentrated while the solvents in the liquids were volatilized. According to Teixeira (2004), the soluble solids content for the same concentration of sugars can vary from one liqueur to another due to the presence of alcohol.

The results showed alcohol content ranging from 12.6 to 21.3 (Table 2), from D to B, respectively. The highest alcohol contents were observed in treatment B (21.3 %v/v) and A (18.16 %v/v). Higher alcohol content values were probably caused by the development of small alcoholic fermentations during maceration, influenced by the amount of sweet potato and lemon balm in the treatments.

Results close to those obtained in this study were reported by Castro (2021) and Leonarski et al. (2021) in artisanal pitaya (polyrhizus) liqueur (Castro, 2021) and a liqueur made from three native Brazilian fruits (Leonarski et al. 2021).

Results in line with those of the present research were reported by Dias et al. (2011), with an alcohol content of 21 % in yellow passion fruit liqueur. In other study Lemes et al. (2021), assessed an alcohol content of 21.8% for pomegranate liquor.

Higher values than those obtained in this study were revealed by Teixeira et al. (2007), who, obtained an alcoholic strength of 24 % for banana liqueur. The differences found could be attributed to the different strengths of brandy used in the preparation of the liqueurs, which should influence the alcohol content.

Table 2: Physicochemical characteristics of combined sweet potato and lemon balm liqueurs.

Treatments	Parameters
Treatments	pH	Titratable acidity (%)	Soluble solids (ºBrix)	Alcoholic strength (%v/v)
A	6.51±0.04^a	2.26±0.15^d	24.30±0.1^b	18.16±0.11^b
B	6.40±0.03^b	6.23±1.05^c	26.20±0.1^a	21.30±0.1^a
C	6.04±0.01^c	9.76±0.85^b	17.80±0.1^c	15.30±0.1^c
D	5.43±0.01^d	12.66±1.51^a	17.76±0.15^c	12.60±0.1^d

Means ± standard deviation, samples followed by the same letter in the same column do not differ significantly at 5% significance level. (A) 30% water, 15% sweet potato and 2% lemon balm; (B) 35% water, 10% sweet potato and 1.5% lemon balm; (C) 45% water, 5% sweet potato and 1% lemon balm; (D) 47% water, 0% sweet potato pulp and lemon balm, 45% alcohol and 8% sugar.

Sensory analysis

The results of the acceptability analysis carried out using a hedonic scale of 1 to 9 points for the liqueurs A-D are shown in Table 3. These results include appearance, color, texture, flavor, aroma, aftertaste and overall assessment.

The results obtained for the appearance ranking from 4.34 to 5.71, from B to D respectively. Lower scores were observed in treatments A and B. There were no significant differences (p>0.05) in the treatments (A, B and C), but treatment D was statistically different to B. This difference can be explained by the composition of the liquor, as it lacked sweet potato pulp and lemon balm, factors that helped the product's appearance (Table 3).

Higher appearance results were found by Coelho et al. (2019) who developed a grape-based liqueur and obtained 8.5. Pereira et al. (2012) in other study obtained a score of 7.12 for the acceptability of S. tuberosa liqueur. Carvalho and Silva (2017) produced and evaluated the appearance of liqueur with reduced calorie content, and obtained and appearance value of 6.68. Zinato (2021) who studied seriguela liqueurs, obtained scores in the range of 6.95 to 7.32.

For color, we obtained scores from 4.71 (liquor B), to 5.98 (liquor A). Statistically, the samples (A, C and D) did not differ significantly (p ≥0.05). Color values in line with those obtained in this study were reported by Barata (2013), obtaining scores ranging from 5.5 to 5.8 for artisanal liqueurs. And Lemes et al. (2021), that obtained a score of 5.46 for liqueurs from the native fruit curriola (Pouteria ramiflora).

Higher results were reported by Silva et al, (2017), Rodrigues (2017) and Dias et al. (2011). Silva et al, (2017) developing a mandarin peel liqueur with a score of 7.32 - 7.81. Rodrigues (2017) obtained a score of 6.98 to 7.17 for guabiroba liqueur. For Dias et al. (2011) she core was 7.3 for yellow passion fruit liqueur.

Table 3: Acceptance results for sweet potato liqueur.

	Attributes
Treatments	Appearance	Color	Texture	Flavor	Aroma	Aftertaste	Overall assessment
Treatments	Appearance	Color	Texture	Flavor	Aroma	Aftertaste	Overall assessment
A	4.83±0.95^ab	5.98±1.01^a	6.11±0.95^a	5.98±0.99^a	6.04±0.86^a	6.43±0.94^ab	6.20±0.99^b
B	4.34±0.93^b	4.71±0.98^b	6.31±0.91^a	5.65±0.96^a	6.08±0.96^a	6.88±0.93^ab	7.07±0.95^a
C	5.01±0.89^ab	5.55±0.87^a	6.32±0.93^a	5.86±0.93^a	6.04±0.89^a	6.31±0.98^b	5.74±0.98^b
D	5.71±0.99^a	5.85±0.95^a	6.25±0.93^a	6.7±0.94^a	6.19±0.96^a	7.08±0.99^a	6.46±0.96^ab

Means ± standard deviation, samples followed by the same letter in the same column do not differ significantly at 5% significance level. (A), 30% water, 15% sweet potato and 2% lemon balm; (B), 35% water, 10% sweet potato and 1.5% lemon balm; (C), 45% water, 5% sweet potato and 1% lemon balm; (D), 47% water, 0% sweet potato pulp and lemon balm, 45% alcohol and 8% sugar.

The results for texture (Table 3), were of 6.11– 6.32 from treatment D to C, respectively. There were no significant differences (p>0.05) between the treatments for texture attribute. Similar results were described by Nascimento et al. (2022) in the sensory evaluation of a handmade clove and cinnamon liqueur, obtaining a score of 6.63 for texture attribute.

Lemes et al. (2021), obtained scores ranging from 5.19 to 5.84 for curriola liqueurs. Values higher than those found in this research were reported by Coelho et al. (2019) when carrying out the development and sensory evaluation of Cv. Isabel, with a score of 8.52 for the texture attribute.

In terms of flavor, the treatments analyzed varied between 5.65 and 6.19 at the extremes of "neither liked nor disliked" and "slightly liked". Treatment D scored highest in the 6.19 range, with considerable variation from the others. Then there was a permanently constant range in the scores for treatments A, B and C at around 5.93, 5.65 and 5.86 respectively. Statistically, all the treatments showed no significant differences (p<0.05) between them (Table 3).

Values similar to those of the present experiment were revealed by Rodrigues (2017), Barata (2013) and Lemes et al. (2021). According to Teixeira et al. (2007), the right combination of alcohol content and sugar content plays a fundamental role in consumer acceptance of liqueurs. When you increase the percentage of sugar (w/v) in a liqueur, you usually also increase its alcohol content (% v/v). In this way, a balance can be achieved between the sweet taste and the alcoholic flavor.

With regard to the aroma attribute, the results obtained indicated averages anchored in the terms from formulation to C range of 6.19 to 6.04, respectively. No significant differences were observed between the samples (A, B, C and D) for the aroma attribute (Table 3). Cunha et al. (2013) reported similar results for cajá-mango liqueur with different concentrations of pulp. Pereira et al. (2012) obtained 6.40 for S. tuberosa liqueur and Zinato (2021) obtained scores of around 6.79 seriguela liqueurs.

Aftertaste scores ranged from 6.31 to 7.08. The highest score (7.08) was observed in treatment D, followed by treatments A, C and B which showed non-significant variations between them with averages of around 6.43; 6.31 and 6.88 respectively. No significant differences were observed between treatments A, B and D (p> 0.05) (Table 3). Consistent results were reported by Zinato (2021), who found residual flavor in the range of 6.64 to 7.30 seriguela liqueurs. Moraes (2018) also has obtained consistent results for the aftertaste scores (6.25) when carrying out the development and analysis of blackberry liqueur with ginger, made from artisanal cachaça from the west of Bahia.

The overall evaluation indicated scores ranging from 5.74 to 7.07, with the highest score (7.07) being given to formulation B on the "I liked it moderately" rating scale, followed by treatment D with 6.46 and, consequently, there was a decline between treatments A and C in the range of 5.74 and 6.20, respectively. Statistically, samples A and C did not differ significantly (p>0.05) from each other. On the other hand, there was a significant difference between sample B and samples A and C (Table 3). Similar scores for the overall evaluation were obtained by Barata (2013), Zinato (2021) and Lemes et al. (2021).

Purchase intention test

The results of the purchase intention test for sweet potato pulp and lemon balm liqueurs are shown in Figure 2. Formulation B of the liqueur stood out as the best formulation in the purchase intention test, as 25 % of the tasters rated it "would buy/prefer". This was followed by formulation D, A and C with 23 %, 11 % and 7 %, respectively, of the tasters' votes.

Lemes et al. (2021) reported results in line with those of the present study. (2021) for curriola liqueurs with 23% and 7% of tasters would surely buy it. Coelho et al. (2019), when carrying out the development and sensory evaluation of the grape liqueur observed that only 25% of the tasters said they would buy it, and only 2.08 % "might buy it". Dias et al. (2011) found that 8% would not buy the product when they characterized passion fruit liqueur sensorially. This shows that there is a tendency to reduce the alcohol content of liqueurs, with the most common preference being for liqueurs with an alcohol content of less than 25% by volume Pereira et al. (2012) in their study on the preparation, physicochemical characterization and acceptability of S. tuberosa liqueur, observed that (60%) said they would buy the product Alves et al. (2011), who analyzed the sensory perception of a typical Amazonian açaí-based liqueur, found that 78.6% of tasters said they would buy it, 19.4% said "maybe" and only 1.9% said "no".

Figure 2: Liqueur purchase intention test for liquor prepared with: (A) 30% water, 15% sweet potato and 2% lemon balm; (B) 35% water, 10% sweet potato and 1.5% lemon balm; (C) 45% water, 5% sweet potato and 1% lemon balm; (D) 47% water, 0% sweet potato pulp and lemon balm, 45% alcohol and 8% sugar.

Acceptability index

Figure 3 shows the results obtained in the acceptability test for liqueurs made from orange- fleshed sweet potato pulp and lemon balm.

The acceptability index of the liqueur formulations produced indicated that the best formulation was B, with 71.14 %. A low acceptability index (AI) was observed in formulations A, C and D, with acceptance indices of 65.98, 64.8 and 69.38 %, respectively.

Teixeira (2001) states that for a product to be considered sensorially acceptable, its acceptability index must be equal to or greater than 70 per cent. In addition, Dutcosky (2007) states that for a product to be accepted in terms of its sensorial characteristics, its acceptability index must be at least 70 per cent.

Similar values were reported by Silva et al. (2017) in the formulation of a mixed acerola and guava liqueur, where the acceptability values found for the sensory attributes were between 72 and 84 %, the overall evaluation obtained scores between 76 and 78 % for 3 formulations,

Oliveira et al. (2019) in the development of graviola liqueur with different types of treatment achieved average acceptability values between 7g2 and 77 % for 7 formulations, and also by Barata (2013) when developing artisanal liqueur formulations, obtained acceptability of 69 to 70 %.

Figure 3: Acceptability index of sweet potato and lemon balm liqueur: (A) 30% water, 15% sweet potato and 2% lemon balm; (B) 35% water, 10% sweet potato and 1.5% lemon balm; (C) 45% water, 5% sweet potato and 1% lemon balm; (D) 47% water, 0% sweet potato pulp and lemon balm, 45% alcohol and 8% sugar.

Conclusions

With this study, it was possible to produce liqueurs based on orange-fleshed sweet potato with partial incorporation of lemon balm using four different types of formulations. The physicochemical parameters of liqueurs showed significant differences in terms of pH, titratable acidity, total soluble solids content and alcohol content. Sensorially, the liqueur produced with 35% of water, 10% of sweet potato and 1.5% of lemon balm was the best in terms of texture, flavor, aroma and aftertaste, achieving a sensory acceptance index of 71.14%, with 25% of tasters saying they would buy it. It was found that sweet potato and lemon balm are alternatives for making liqueurs and can contribute to product diversification.

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