Whey is a by-product of the dairy industry that is well known for its technological and nutritional properties (Ozorio et al., Reference Ozorio, Silva, Prates, Bloch, Takeiti, Gomes, da Silva-Santos, Deliza, Brígida, Furtado, Mellinger-Silva and Cabral2019). A total of 1.6 billion liters of whey are generated each year during the manufacture of cheeses and fermented dairy products with high protein content, such as Greek-style yogurt (Schäfer et al., Reference Schäfer, Sebald, Dunkel, Hofmann, Rosenthal, Schuster, Atamer and Hinrichs2019). Part of the produced whey is still used for low-value applications, such as pig feeding, land application or anaerobic digestion (Xu et al., Reference Xu, Hao, Guzman, Spirito, Harroff and Angenent2019). Production of whey-based beverages appears to be the most economical and simplest solution for whey utilization in human nutrition (Barukčić et al., Reference Barukčić, Jakopović and Božanić2019).
Whey dairy beverages (WDB) are fermented or non-fermented products in which whey is used as an ingredient (Janiaski et al., Reference Janiaski, Pimentel, Cruz and Prudencio2016). This type of product has a promising food market, mainly because of the sustainability appeal and the putative health benefits associated with the bioactive compounds present in the whey (Coutinho et al., Reference Coutinho, Silveira, Fernandes, Moraes, Pimentel, Freitas, Silva, Raices, Ranadheera, Borges, Neto, Tavares, Fernandes, Fonteles, Nazzaro, Rodrigues and Cruz2019). Furthermore, the demand for beverages containing functional components, such as probiotics, has increased and driven the market (Silva e Alves et al., Reference Silva e Alves, Spadoti, Zacarchenco and Trento2018). Probiotics are living microorganisms that confer benefits to the health of the host when administered in adequate amounts, in general at least 106–107 cfu/ml in the product (Hill et al., Reference Hill, Guarner, Reid, Gibson, Merenstein, Pot, Morelli, Canani, Flint, Salminen, Calder and Sanders2014).
The development of carbonated beverages is increasing, mainly because of the thirst quenching and refreshing properties of the products, and due to the fact that carbonation is considered an inexpensive and safe process (Silva e Alves et al., Reference Silva e Alves, Spadoti, Zacarchenco and Trento2018). However, the carbonation process can result in probiotic death (Ansari et al., Reference Ansari, Hesari, Ahmadi, Giasifar and Aiaseh2013). Previous studies are mainly related to the processing of probiotic carbonated fermented whey dairy beverages (Shah and Prajapati, Reference Shah and Prajapati2014; Sağlam et al., Reference Sağlam, Sarioglu, Karahan and Oner2019) because the fermentation step helps in increasing the probiotic viability. As far as the authors know, there are no reports on probiotic carbonated non-fermented whey dairy beverages based on a mixture of whey and milk. Therefore, this study aimed to evaluate the impact of the addition of probiotic culture Lactobacillus casei and/or carbonation on the chemical composition, physicochemical characteristics, probiotic survival and sensory acceptance of passion-fruit flavored whey dairy beverages during refrigerated storage (30 d/4°C).
Materials and methods
Whole UHT milk (3% fat, Parmalat, São Paulo, SP) and whey powder (reconstituted to 14% total solids, Confepar, Londrina, PR) were mixed in the ratio of 70 : 30, heated at 90°C/5 min in a water bath and cooled to 10°C. Then, 5% sugar (União, Rio de Janeiro, RJ) and 5% passion fruit pulp (Redondo, Cambé, PR) were added. The passion fruit pulp was previously heated at 90°C/1 min and cooled to room temperature (25°C). The WDB was cooled to 4°C and divided into four portions, corresponding to the following treatments: CO2-free and without L. casei (CONTROL); CO2-free with L. casei (PRO); CO2 addition and without L. casei (CARB); and CO2 and L. casei addition (PRO-CARB).
For the carbonated beverages, CO2 (food grade) was bubbled directly into the samples (4°C) with the aid of a sanitized hose. The CO2 concentration added was the same for all formulations and controlled by the decrease in 0.3 units in the pH value, defined in a preliminary test based on the sensory aspect. The lyophilized probiotic culture Lactobacillus casei (Chr Hansen Valinhos, Brasil) was activated at 37°C for 3 h in sterilized skim milk and added to the products at a concentration of 2 ml/100 ml (7.8 log cfu/ml), after the carbonation step. Then, the beverages were packaged in sterilized polyethylene terephthalate (PET) bottles (240 ml) and stored at 4°C.
The pH, titratable acidity, total solids, protein, ash, fat, and carbohydrates were determined according to AOAC (2005). L. casei was determined in Man, Rogosa and Sharpe (MRS) Agar (Becton, Dickinson, and Company Sparks, USA) incubated at 37°C for 72 h under anaerobic condition (Shah and Prajapati, Reference Shah and Prajapati2014). The chemical composition was evaluated on the first day of storage, while the pH, titratable acidity and probiotic survival were performed on the 1, 7, 15 and 30 d of storage, which is the general shelf life of whey dairy beverages.
The sensory evaluation was performed by 51 consumers. The evaluation was conducted in individual booths under white light and the samples were served at 4°C in 50 ml plastic cups coded with random three-digit numbers, presented in a monadic form. The beverages were evaluated for overall acceptance, flavor, and aroma, using a 9-point hedonic scale ranging from ‘1 – disliked very much’ to ‘9 – liked very much’.
All physicochemical and microbiological analyses were performed in triplicate and the experiment was repeated three times. The experimental design was a split-plot, in which the main factor was the formulation and the second factor was the storage time. The results were submitted to Analysis of Variance (ANOVA) and Tukey test (P = 0.05) using the Statistica 8.0 software (Stat Soft, Inc).
Results and discussion
The chemical composition of the products (g/100 mL) was in the following range: 13.3–14.2 for total solids, 0.7–0.8 for ash, 2.4–3.2 for protein, 1.9–2.0 for fat and 7.4–9.3 for carbohydrates (Table 1). The addition of L. casei and/or carbonation did not impact the chemical composition (total solids, protein, ash, fat and carbohydrate contents, P > 0.05). Our data are similar to those reported in a previous study for whey dairy beverages (Janiaski et al., Reference Janiaski, Pimentel, Cruz and Prudencio2016). Therefore, the addition of L. casei and/or carbonation had no negative influence on the nutritional value of the products.
Chemical composition of whey dairy beverages (n = 9)
Means ± standard deviations in the same row with the same letters indicate no differences among formulations of whey dairy beverages (P > 0.05). (CONTROL: CO2-free and without L. casei; PRO: CO2-free and with L. casei; CARB: with CO2 and without L. casei; PRO-CARB: with both CO2 and L. casei).
Table 2 presents the pH and acidity of the products during refrigerated storage. The whey dairy beverages presented pH values of 5.3–6.0 and acidity of 0.40–0.57% lactic acid, corroborating a previous study (Janiaski et al., Reference Janiaski, Pimentel, Cruz and Prudencio2016). The addition of L. casei and/or carbonation did not impact on the pH values of the whey dairy beverages (P > 0.05) but increased the acidity (P ≤ 0.05). The maintenance of the pH values is related to the buffering capacity of the whey proteins (McCarthy et al., Reference McCarthy, Wilkinson and Guinee2017). The initially increased acidity of the probiotic whey beverage can be related to the addition and/or adaptation of the probiotic culture to the medium, with the production of organic acids, mainly lactic acid (Sperry et al., Reference Sperry, Silva, Balthazar, Esmerino, Verruck, Prudencio, Neto, Tavares, Peixoto, Nazzaro, Rocha, Moraes, Gomes, Raices, Silva, Granato, Pimentel, Freitas and Cruz2018). The CO2 addition increases the acidity due to the presence of carbonic acid in the medium (Ansari et al., Reference Ansari, Hesari, Ahmadi, Giasifar and Aiaseh2013). The higher acidity of the probiotic and carbonated products can increase the shelf life of the products but can have an impact on the probiotic survival or consumer acceptance of the products (Sperry et al., Reference Sperry, Silva, Balthazar, Esmerino, Verruck, Prudencio, Neto, Tavares, Peixoto, Nazzaro, Rocha, Moraes, Gomes, Raices, Silva, Granato, Pimentel, Freitas and Cruz2018). During storage, the control and probiotic formulations behaved similarly, with the maintenance of the pH and acidity values (P > 0.05). However, the carbonated products had a decrease in the acidity values during storage (P < 0.05). Probably, the carbonic acid could have been hydrolyzed during the storage time, reducing the acidity of the products. Furthermore, there may have been CO2 losses during the storage period, although the products did remain carbonated until the end of the refrigerated storage (30 d).
Physicochemical and microbiological characteristics of the whey dairy beverages during refrigerated storage (n = 9)
Means ± standard deviations in the same row with the same small letters indicate no differences among formulations of whey dairy beverages (P > 0.05). Means ± standard deviations in the same row with the same capital letters indicates no differences during refrigerated storage (P > 0.05). (CONTROL: CO2-free and without L. casei; PRO: CO2-free and with L. casei; CARB: with CO2 and without L. casei; PRO-CARB: with both CO2 and L. casei).
The carbonation did not impact on the probiotic survival in the whey dairy beverages (P > 0.05, Table 2). Both evaluated products presented an increase in the probiotic viability at the end of the storage period (P ≤ 0.05), which is related to a possible proteolytic activity of the probiotic cultures upon the whey proteins and release of important compounds for the probiotic survival (Sperry et al., Reference Sperry, Silva, Balthazar, Esmerino, Verruck, Prudencio, Neto, Tavares, Peixoto, Nazzaro, Rocha, Moraes, Gomes, Raices, Silva, Granato, Pimentel, Freitas and Cruz2018). L. casei remained viable and stable in both products during the 30 d of refrigerated storage (P > 0.05), presenting satisfactory populations (7 log cfu/ml). Therefore, the total number of probiotic microorganisms in the whey dairy beverages exceeded 106 cfu/mL throughout the storage time, which is the minimum probiotic population required in food at the time of consumption (Hill et al., Reference Hill, Guarner, Reid, Gibson, Merenstein, Pot, Morelli, Canani, Flint, Salminen, Calder and Sanders2014; Silva e Alves et al., Reference Silva e Alves, Spadoti, Zacarchenco and Trento2018). The results suggest that the carbonated whey dairy beverage is a good matrix for the addition of L. casei as a probiotic culture.
Table 3 presents the sensory scores of whey dairy beverages. All formulations presented scores higher than 6 in a 9-point hedonic scale, indicating that the consumers liked at least slightly the products. The addition of L. casei and/or carbonation did not impact on the acceptance of the whey dairy beverages in flavor or overall impression (P > 0.05) but decreased the aroma acceptance (P ≤ 0.05). The results indicate that the higher acidity of the probiotic and carbonated products (Table 2) did not impact on the consumer acceptance in the flavor. The presence of the probiotic culture and/or of CO2 may have altered the volatile profile of the products, resulting in the appearance of compounds with negative influence on the aroma, and/or disappearance of compounds that contribute positively to it. Future studies should evaluate the volatile compounds of the products to confirm the results of the present study.
Sensory acceptance of the whey dairy beverages (n = 51)
Means ± standard deviations in the same row with the same letters indicate no differences among formulations of whey dairy beverages (P > 0.05). (CONTROL: CO2-free and without L. casei; PRO: CO2-free and with L. casei; CARB: with CO2 and without L. casei; PRO-CARB: with both CO2 and L. casei).
In conclusion, this is the first report of a carbonated non-fermented whey dairy beverage and the results demonstrate that it is possible to develop a probiotic passion-fruit flavored carbonated whey dairy beverage with suitable chemical composition, sensory acceptance (>6 in 9-point hedonic scale) and probiotic viability (>7 log cfu/ml) that could be refrigerated stored for 30 d.
Acknowledgments
This work was supported by Fundação Nacional de Desenvolvimento de Ensino Superior Particular/FUNADESP.
