Investigation of Antioxidant Capacity, Chemical Composition, and Sensory Characteristics Using Camu-Camu Powder in the Production of Fresh Cow’s Cheese

Abstract

(1) Background: Research into incorporating plant powders into dairy products is growing because they significantly increase the nutritional value of the finished products, making them a more attractive option for consumers seeking healthier alternatives. The objective of this study is to develop a novel dairy product by incorporating camu-camu powder into fresh cow’s cheese. The material has been identified as a promising candidate due to its multiple health benefits and high antioxidant content, particularly vitamin C; (2) Methods: The stability of the product during storage was therefore evaluated by analysing its acidity, pH, dry matter content, water activity, syneresis and water holding capacity. The impact of camu-camu powder on the antioxidant activity of the cheese samples was determined using the DPPH method. A sensory evaluation was conducted to ascertain the potential functional properties and consumer acceptability of the subject; (3) Results: The bioactive compounds present in the powder have been shown to enhance the antioxidant capacity of fresh cheese, with the 2% sample demonstrating the most effective antioxidant performance. From a sensory perspective, the 1.5% sample received the highest ratings from tasters. The 1% sample is distinguished by its notable colour stability during storage. Physicochemical analysis shows that camu-camu powder is a sustainable ingredient that improves the quality and extends the shelf life of the finished product; (4) Conclusions: This information is indispensable for the evaluation of the safety and efficacy of camu-camu powder in dairy products. Moreover, it may serve as a point of departure for future studies involving the development of other food products with bioactive compounds using unconventional raw materials.

1. Introduction

The increasing adoption of diets centered around the consumption of fruits, vegetables, herbs, and spices can be attributed to the anti-inflammatory and antioxidant properties of these foods [1]. Vitamin C is the most significant dietary antioxidant and functions as a potent anti-inflammatory agent [2]. The regular consumption of antioxidants has been demonstrated to reduce the risk of stroke, a leading cause of disability worldwide [3,4]. The regular intake of antioxidants has been demonstrated to offer a protective effect against free radicals, thereby enhancing longevity [5].

The distinctive appearance, flavor, and nutritional value of tropical fruits have garnered the attention of food producers [6]. The Amazon region is distinguished by its high biodiversity of tropical fruits, which possess high nutritional value, therapeutic potential, and agro-industrial potential [7]. Fruit cultivation constitutes a pivotal component of the global agricultural landscape, exerting a substantial influence on employment and economic revenue in rural regions. This agricultural practice plays a pivotal role in enhancing food security [8,9,10,11].

Camu-camu (Myrciaria dubia) is an exotic tropical fruit native to the Amazon region [12] that belongs to the Myrtaceae family. The fruits are small, round, red berries [13]. It is primarily exported from Peru [7,14].

Camu-camu is noteworthy for its high vitamin C content, with 6 g/100 g of fresh pulp containing 50 mg of vitamin C [6,12,14]. This makes it one of the world’s richest sources of the supplement [15]. The nutrient profile is assured by the presence of carotenoids, which are abundant in potassium, iron, calcium, and phosphorus. The nutrient profile is further enhanced by phenolic compounds, including ellagic acid [1] and anthocyanins [7]. The antioxidant capacity of these compounds has been the subject of extensive research in both in vivo and in vitro studies [2,6,7,12,13,16]. The compounds have also demonstrated neuroprotective [12], antihypertensive [12], antimicrobial [16], antigenotoxic [16], and anti-inflammatory [2,14] properties.

The fruit’s high water content contributes to its perishability, leading to a reduction in nutritional value and shelf life due to enzymatic and chemical deterioration [1]. Consequently, camu-camu fruits are processed to produce a variety of derivatives, including pulp, extract, and fruit juice [12]. The production of powder involves the pasteurization of fruit, a process that facilitates its transport for export and enhances its commercial viability in the food industry. Although powder can be used as a dietary supplement, there are no known safe dosages because of its possible harmful effects and its impact on various developmental stages through varying oxidative metabolism modulation [1].

In the contemporary dairy industry, there is an increasing emphasis on innovative ideas that can enhance the quality of cheese. This emphasis is particularly pronounced in the sector dedicated to the production of cheese [17,18,19]. Fresh cheeses play an important role in the diet and are a noteworthy category of cheeses with excellent nutritional quality [20] that do not mature. These goods are characterized by a uniform, spreadable consistency and a subtle sour taste [21]. Cheese is a functional dairy product [22] that is consumed for its high nutritional content. This content provides energy and has been shown to help prevent diseases, including diabetes, obesity, hypertension, and digestive issues [23].

Research on the incorporation of plant ingredients containing bioactive compounds in dairy products is increasing [24] due to the reduced need for synthetic chemical preservatives in processed foods [25], and from the producer’s point of view, these products can improve sales and range diversification [26]. Curti et al. developed ice creams with the addition of camu-camu pulp (20–26%). All formulations exhibited elevated concentrations of antioxidants and vitamin C, with the 20% camu-camu pulp formula demonstrating the highest sensory acceptance [27]. In 2021, Grigio et al. [28] conducted a study in which popsicles were prepared with camu-camu pulp (20 and 25.9%). The participants indicated a preference for products with the highest pulp content. The incorporation of freeze-dried peel resulted in an augmentation of bioactive compounds and an enhancement of the product’s functional capacity [28]. In 2015, Aguiar and Souza [29] prepared yogurts with camu-camu pulp at concentrations of 10, 13, and 15%. As the concentration of pulp increased, reaching 13% and 15%, the acidity levels of the samples increased concomitantly. However, these higher acidity levels were not accompanied by an increase in acceptance rates. The formula exhibiting the lowest pulp concentration (10%) demonstrated higher levels of acceptance [29]. In a 2015 study, Rosa et al. evaluated the incorporation of Amazonian fruits into buffalo milk yogurt, finding high levels of vitamin C [30]. In 2019, Fidelis et al. [31] conducted a study to evaluate the addition of different concentrations of freeze-dried camu-camu seed extract to yogurt. The results of each antioxidant assay indicated a dose-dependent effect, suggesting that an increase in the concentration of camu-camu resulted in a concomitant enhancement of the in vitro antioxidant activity of the yogurt samples. The products were well-received from a sensory perspective, suggesting that the ingredient could be used to make functional yoghurts [31].

Consequently, conducting scientific studies is imperative to ascertain whether dairy products fortified with fruit exhibit nutritional and functional properties, as well as distinctive characteristics and flavors that not only appeal to consumers but also contribute meaningfully to their health [32]. The objective of this study is to develop a novel dairy product by enhancing fresh cow’s cheese with camu-camu powder, which is abundant in antioxidant compounds. Therefore, the stability of physicochemical and antioxidant properties during the storage period of cheese samples was evaluated. A sensory evaluation was also conducted to characterize potential functional properties and consumer acceptability.

2. Materials and Methods

2.1. Obtaining Samples of Fresh Cow’s Cheese with Added Camu-Camu

The collection of samples and subsequent analyses were conducted within the laboratory of the Research Center for Biotechnology and Food Engineering (CCBIA) at Lucian Blaga University of Sibiu. According to a technological recipe formulated by the research team, the fresh cow’s cheese was processed in a laboratory setting using the following ingredients: cow’s milk purchased from an organic farm in Sibiu County, liquid rennet produced by Ideal Still Exim SRL, and organic camu-camu powder produced by Crud și Sănătos.

The raw milk was subjected to a heating process at 70 °C and subsequently cooled to 34 °C. The addition of liquid rennet, at a rate of one milliliter per five liters of milk, occurred once the desired cooling temperature had been achieved. To facilitate the process of coagulation, the inoculated milk was allowed to rest at room temperature for a period of ninety minutes. The coagulum is subsequently processed, and the whey is drained by removing it using a cheesecloth sieve. Subsequent to the draining of the whey, the camu-camu powder is incorporated into the mixture. Following a series of trials, the proportions were established as shown in

Table 1. List of ingredients added to fresh cow’s cheese.

Sample Code	Fresh Cow’s Cheese [g]	Camu-Camu Powder [g]
0%	100	0
1%	100	1
1.5%	100	1.5
2%	100	2

.

Fresh cheese was placed in hermetically sealed plastic containers with a capacity of 150 g and kept in the refrigerator at 6 °C for 16 days.

2.2. Physicochemical Determinations

The Thörner method was used to determine acidity, and a pH meter was used to measure pH. Water activity was measured using a Novasina device, and dry substance was measured using a thermobalance. The entire working method is presented in the 2024 article [23]. Each sample was subjected to five repetitions.

The centrifugation test was employed to ascertain the water holding capacity [33]. Accordingly, 5 g of the sample are placed in a centrifuge tube equipped with a stopper. The samples are then subjected to a centrifugal process at a temperature of 4 °C and an angular velocity of 4500 revolutions per minute (rpm) for a duration of 15 min. This centrifugal process is carried out using a centrifuge model NF 800R, manufactured by Nuve. Subsequent to centrifugation, the resulting pellet is weighed. The water holding capacity is calculated using Formula (1).

$$\mathrm{WHC} (\%)=(1-{\displaystyle \frac{{\mathrm{W}}_1}{{\mathrm{W}}_2}}) · 100$$

(1)

where W₁—weight of supernatant after centrifugation [g]; W₂—weight of cheese sample [g]. Five repetitions were made for each sample.

The syneresis was determined by drainage using the method presented in the article published in 2021 [34]. Each sample was subjected to five repetitions.

The fat content of the control sample was determined using the Van Gulik method (butyrometric acid method), in accordance with the SR ISO 3433:2009 standard [35]. The International Organization for Standardization (ISO) and the International Dairy Federation (IDF) recommend the volumetric measurement of the sample (ISO 3433:2008 and IDF 222:2008) [36].

2.3. Determination of Antioxidant Activity

The method adapted from Patel et al. [37] in 2016 was used for the extraction of compounds. The antioxidant activity was determined using a DPPH method adapted from Tylkowski et al. in 2011 [38]. The methods used to extract compounds and determine antioxidant capacity and activity are the same as those described in articles published in 2022 [39] and 2020 [40]. Each sample was subjected to five repetitions.

2.4. Sensory Analysis

The five-point hedonic scale test (1 = dislike very much; 2 = “dislike”; 3 = “neither like nor dislike”; 4 = like; and 5 = like very much) was utilized to assess the acceptability of the sample. An evaluation of the sensory characteristics of fresh cow’s cheese samples was conducted after a storage period of 1, 8, and 16 days. A total of 13 evaluators, comprising both female and male participants, including teachers and students from the Faculty of Agricultural Sciences, Food Industry and Environmental Protection at Lucian Blaga University of Sibiu, with ages ranging from 18 to 64 years, participated in the evaluation process. The subjects selected for this study are consumers of dairy products who do not have lactose intolerance or sensitivity. Each participant was informed about the purpose of the test and the requirements of the analysis through an informed consent form. The cheese samples were presented in 100 cm³ plastic containers. The containers utilised in this study are indistinguishable in terms of size, shape and colour. The tasting room is well lit, with an interior temperature of 20 °C, and is equipped with water for rinsing the mouth, a designated area for expectoration, and ample space for the placement of samples and evaluation sheets. The following characteristics were evaluated: appearance, taste, odor, and consistency. The study was conducted in accordance with the Declaration of Helsinki, and approved by the Ethics Committee of Lucian Blaga University of Sibiu (no. 21 on 23.05.2025).

2.5. Color Determination

The color of fresh cheese samples was measured using a Minolta CR-400 colorimeter (Minolta Camera Co., Osaka, Japan) with a viewing angle of 10°, calibrated with a standard plate (L* = 89.25, a* = −0.14 and b* = −1.61). CIELAB parameters are thus determined, including L (brightness, ranging from 0 to 100), a (green-red composite, between −80 and 100) and b (blue-yellow composite, between −80 and 70).

Color differences (ΔE) were calculated by Formula (2).

ΔE = L* − L2 + a* − a2 + b* − b2

(2)

where L* = 89.25, a* = −0.14 and b* = −1.61 are the parameter values of the standard plate; L, a and b are the color parameters of the samples [41]. Five repetitions were made for each sample.

2.6. Statistical Analyses

All experiments were performed in pentaplicate (except for sensory analysis), presenting the data as the mean and standard deviation of the three independent experiments (day 1, day 8 and day 16). The statistical processing of the results was carried out using Minitab version 14. To ensure the validity of the results, a statistical analysis was conducted. Specifically, analysis of variance (ANOVA) and Duncan’s multiple range test, applied at a significance level of 5% (p < 0.05), were used to compare the mean values and evaluate the results.

The impact of independent factors on the color and sensory characteristics of the cheese samples was determined using the response surface method (RSM). The independent variables employed in this study were storage time (X1) and camu-camu concentration (X2). The dependent variables of interest included appearance (Y1), taste (Y2), odor (Y3), firmness (Y4), L* value (Y5), b* value (Y6), a* value (Y7), and ΔE (Y8). The design was obtained from the design expert software, which contained 12 runs. The range of variables selected for camu-camu concentration and storage time was 0–2% and 1–16 days, respectively.

The experimental design is included in Supplementary Material S1.

3. Results and Discussion

3.1. Physicochemical Determinations

As illustrated in

Table 2. Evolution of acidity, pH, dry matter content, water activity, syneresis index and water holding capacity in cheese samples during the storage period.

Item	Camu-Camu Concentration [%]	Storage Time [Days]
		1	8	16
Acidity [°T]	0	72.10 ± 0.100 ab,AB	85.36 ± 0.055 ab,AB	110.74 ± 0.089 a,ABC
	1	90.36 ± 0.055 ab,AB	97.86 ± 0.055 ab,AB	105.32 ± 0.045 a,BC
	1.5	97.56 ± 0.089 ab,A	104.14 ± 0.055 ab,A	112.66 ± 0.055 a,AB
	2	110.28 ± 0.084 ab,A	118.56 ± 0.055 ab,A	123.72 ± 0.045 a,A
pH	0	5.6242 ± 0.00084 a,A	5.2674 ± 0.00055 ab,A	4.8864 ± 0.00055 ab,B
	1	5.5124 ± 0.00055 a,AB	5.0576 ± 0.00055 ab,AB	4.9544 ± 0.00055 b,A
	1.5	5.0784 ± 0.00055 a,ABC	4.9934 ± 0.00055 b,ABC	4.7814 ± 0.00055 b,BC
	2	4.8932 ± 0.00084 a,ABC	4.5266 ± 0.00055 ab,AC	4.2774 ± 0.00055 ab,BC
Dry matter [%]	0	31.12 ± 0.045 ab,ABC	32.62 ± 0.045 ab,AB	32.86 ± 0.089 a,ABC
	1	32.70 ± 0.071 ab,ABC	33.42 ± 0.045 ab,AB	34.22 ± 0.044 a,ABC
	1.5	33.16 ± 0.055 ab,AB	33.78 ± 0.045 ab,A	34.54 ± 0.055 a,AB
	2	33.62 ± 0.045 ab,A	34.24 ± 0.055 ab,A	34.76 ± 0.055 a,A
Water activity	0	0.9515 ± 0.00000 c,B	0.9526 ± 0.00055 ab,A	0.9544 ± 0.00055 a,A
	1	0.9512 ± 0.00045 ab,A	0.9518 ± 0.00045 ab,ABC	0.9526 ± 0.00055 a,BC
	1.5	0.9510 ± 0.00000 c,B	0.9524 ± 0.00055 ab,AB	0.9536 ± 0.00055 a,BC
	2	0.9510 ± 0.00000 c,B	0.9526 ± 0.00055 b,A	0.9536 ± 0.00055 a,BC
Syneresis [%]	0	12.506 ± 0.0055 b,BC	13.406 ± 0.0055 b,BC	14.146 ± 0.0055 a,AB
	1	13.856 ± 0.0055 ab,ABC	14.726 ± 0.0055 ab,BC	15.366 ± 0.0055 a,AB
	1.5	14.546 ± 0.0055 b,AB	15.026 ± 0.0055 b,AB	15.606 ± 0.0055 a,AB
	2	14.976 ± 0.0055 ab,A	15.414 ± 0.0055 ab,A	15.744 ± 0.0055 a,A
Water holding capacity [%]	0	74.054 ± 0.0055 ab,A	75.226 ± 0.0055 ab,A	77.552 ± 0.0084 a,A
	1	73.322 ± 0.0084 ab,AB	74.504 ± 0.0055 ab,B	75.626 ± 0.0055 a,AB
	1.5	73.046 ± 0.0055 a,BC	73.846 ± 0.0055 a,B	74.686 ± 0.0055 a,AB
	2	72.182 ± 0.0045 b,BC	72.666 ± 0.0055 b,C	73.204 ± 0.0055 a,AB

Results are presented in the form of mean ± standard deviation (n = 5). In each column and row, values with different lowercase and uppercase letters, respectively, are significantly different (p < 0.05). The results in the same column followed by the same uppercase letters are not significantly different (p < 0.05). The results in the same row followed by the same lowercase letters are not significantly different (p < 0.05).

, the data demonstrate a clear influence of storage time on various physicochemical properties of cheese samples with added camu-camu. These properties include acidity, pH, dry matter, water activity, syneresis, and water holding capacity.

The presence of camu-camu has been demonstrated to exert a significant influence on the acidity content of the cheese samples. As the fruit concentration of the cheese sample increases, the cheese’s acidity level concomitantly rises. One potential explanation for this phenomenon is the high acidity of the camu-camu pulp, which has been reported to range from 4.48 to 5.48 meq/kg, as indicated in a study by Freitas et al. (2016) [42]. Alternatively, another study by Sarmento et al. (2019) [32] suggests an acidity level of 2.04% citric acid. During the 16-day storage period, the acidity levels of the cheese samples exhibited an upward trend, with the lowest values being recorded on the first day of storage. Pham et al. also provide documentation of lactic acid accumulation in 2020 in research carried out on fresh cheese made with milk powder [18]. According to Sarmento et al. (2019) [32], the change in acidity can also be directly related to the fruit that was added. Consequently, it can be emphasized that the increase in acidity of the fresh cheese samples with added camu-camu is more stable, with values increasing slightly during storage compared to the control sample [32].

The pH of the cheese samples exhibited a decline in titratable acidity during the storage period, with a concomitant increase in pH observed at higher camu-camu concentrations. This phenomenon can be attributed to the chemical composition of the fruit, which contains a high number of bioactive compounds. The ascorbic acid content exhibited a range between 3.51 ± 0.97 g/100 g powder [43] and 6.30 ± 0.15 g/100 g powder [44]. The total anthocyanin content was found to be 19.63 ± 0.60 mg cyanidin-3-glucoside/100 g powder, and the polyphenol content was determined to be 48.54 ± 0.28 mg/100 g powder [45]. As demonstrated by Fracassetti et al., the total flavonoid content was found to be 3.05 mg/100 g powder (±0.07 mg/100 g powder), the total ellagic acid content was 9.75 mg/100 g powder (±0.10 mg/100 g powder), and the total gallic acid content was 35.96 mg/100 g powder (±0.54 mg/100 g powder) [43]. García-Chacón et al. reported a total malic acid content of 7.20 g/100 g powder (±2.61 g/100 g powder) [44]. The low pH of camu-camu powder is attributable to its high acid content. Preliminary studies have indicated that the pH of camu-camu pulp ranges from 1.44 to 3.5 [24,32,42]. Consequently, the pH of the cheese samples exhibits a decline proportional to the concentration of camu-camu. Fujita et al. (2017) corroborated the decline in pH of soy milk samples during storage, as well as a lower value for samples with higher camu-camu content [46]. On the initial day of storage, the pH values ranged from 4.89 to 5.62, and on the 16th day, the pH values ranged from 4.27 to 4.88. The values obtained in this study are consistent with the findings reported in the study by Rabelo de Oliveira et al. in 2022 [47]. In this study, the pH values of Petit Suisse cheese samples fortified with açai (a type of exotic fruit resembling camu-camu) were measured and ranged from 4.43 to 4.72 [47].

The dry matter content of the cheese samples exhibited variability on the initial day of storage, ranging from 31.12% to 33.62%. The obtained results align with the extant data in the literature. Bjekić et al. (2021) conducted an analysis of the dry matter content of fresh cheese samples and reported results ranging from 37.40% to 49.83%, depending on the starter culture utilized [21]. The samples that have been augmented with camu-camu exhibit the highest values because the fruit provides a dry matter content. The moisture content of fruit is notably high, with values ranging from 86.20% to 92.21%, as reported in studies [7,32]. Over the course of the 16-day storage period, there was an observed increase in dry matter content, reaching a maximum of 34.76%.

Water activity (aw) is defined as the amount of free water in food that microorganisms can use for growth. It has been demonstrated that a decrease in the value is associated with a reduction in bacterial growth [48]. The control sample exhibited a higher water activity value compared to those containing camu-camu. The values obtained for this sample differ from the results presented by Wahyuningtyas et al. (2023) for fresh cheese obtained from goat milk, where aw is 0.82 [22]. Given the low water activity exhibited by dehydrated camu-camu residues [48], it can be deduced that the incorporation of camu-camu powder into the samples results in a reduction in water activity compared to the control sample. During the 16-day storage period, a significant increase in aw was observed in all the samples that were analyzed.

The water-holding capacity of cheese is inversely proportional to syneresis, a property that is often more pronounced in low-fat cheeses. Furthermore, the reduced fat content has been demonstrated to enhance the interaction between proteins, thereby promoting whey expulsion. A high rate of syneresis has been observed in the initial days of storage, with a subsequent attainment of equilibrium over time [49]. In the samples that were analyzed, the water holding capacity increased during the 16 days of storage. The control sample exhibited higher values compared to the samples containing camu-camu. The values obtained in this study are consistent with those reported in other studies. In the study conducted by Wang et al. in 2022, the water holding capacity values for fresh goat milk cheese samples ranged from 86.21 to 92.92% [50]. According to extant literature, the syneresis of various types of fresh cheese ranges from 5.23% to 48% [51,52].

The fat content of the control sample on the first day of storage is 8.3%, resulting in a fresh, fatty cheese. During the process of cheese ripening, fat plays an instrumental role in determining the cheese’s texture and flavour profile, particularly contributing to the development of its characteristic aroma [53]. As posited by Wen et al. (2021), the incorporation of fat has been demonstrated to enhance the propensity for creaminess and to bridge the lacunae within the protein network [54]. The decision was taken to ascertain the fat content solely for the control sample due to the fact that camu-camu powder has a total fat content of 0% [1]. Consequently, irrespective of the quantity added, it exerts no influence on the total fat content of the samples.

3.2. Determination of Antioxidant Activity

As illustrated in Figure 1, the antioxidant capacity of samples of cheese with added camu-camu underwent a specific evolution. Antioxidants are molecules with the capacity to decelerate or impede the oxidation of other molecules. These molecules have found extensive application in numerous domains of medicine due to their ability to neutralize free radicals in the blood, which are implicated in the development of cancer, cardiovascular disease, and diabetes [13]. Camu-camu peel has been found to contain a high concentration of ascorbic acid, thus making it an important source of natural antioxidants [25]. In 2016, a study was conducted to ascertain the antioxidant activity of tannins present in the seeds and skins of camu-camu. The analysis utilized DPPH, ABTS, and ORAC assays, with gallic and ascorbic acid serving as standards. The findings indicated that the antioxidant activities of tannins are twice as potent as those of gallic acid and ten times stronger than ascorbic acid [55]. In the present study, the antioxidant capacity of camu-camu powder averaged 78.8% over the course of 16 days of storage. A high antioxidant activity of the fruit is also demonstrated by Do et al. (2021), who indicate an activity of 95.7% at 250 g/mL, with an IC50 value of 17.95 g/mL [16]. Kaneshim et al. (2012) obtained an IC50 value of 29.2 μg/mL for the crude extract [6]. Consequently, a substantial body of research has demonstrated that camu-camu extracts possess antioxidant properties, which have been shown to reduce oxidative stress in vivo and to offer protection against the mutagenic effects of medications on intestinal micronuclei and bone marrow. These findings are further supported by the ability of camu-camu extracts to induce apoptosis and to perform comet assay, a process that has been identified as a predictor of cancer risk [7].

With regard to the control sample, the initial antioxidant activity recorded on the first day of storage was 8.76%, and this activity decreased during storage, reaching 2.78% on day 16. The degree of proteolysis, soluble protein concentration, protein profile, and fermentation method have been demonstrated to exert a substantial influence on the antioxidant-rich characteristics of fresh cheese samples [21]. Utilizing the DPPH assay, Bjekić et al. obtained superior results in fresh kombucha cheese (0.95 μM TE/g), while in the cheese sample, the traditional starter culture was 0.93 μM TE/g [21]. For samples of cheese with added camu-camu, the antioxidant capacity increases in proportion to the fruit content. Furthermore, during the 16-day storage period, a decline in antioxidant activity was observed. The highest values were observed in the cheese sample with 2% added camu-camu. On the first day of storage, the value was 34.16%, and on the 16th day, it was 30.14%. In 2017, Fujita et al. demonstrated the increase in antioxidant capacity of soy milk samples as a function of the concentration of camu-camu that the samples have. It is reasonable to hypothesize that the maintenance of high antioxidant activity during the fermentation process is attributable to the conversion of glycosides to aglycone forms by enzymes produced during the fermentation process. Furthermore, the synergism between phenolic compounds and other bioactive compounds may have contributed to this result [46].

3.3. Sensory Analysis

Sensory evaluation is instrumental in delineating the product properties that are pivotal for customer acceptability [56]. The appearance of the cheese is a significant criterion that influences consumer preferences and alters their perception of the flavor [50]. In this study, the influence of camu-camu concentration and storage time on the sensory properties of fresh cottage cheese samples is represented in Figure 2: A (appearance), B (taste), C (odor), and D (consistency) by response surface plots. A statistical analysis was conducted on the cheese samples to determine if there were any significant differences in appearance, taste, odor, and firmness value. However, the results showed that these characteristics remained constant and did not vary statistically significantly (p > 0.05) over the storage period.

The sensory characteristics of the samples of cheese with added camu-camu are accentuated during storage, as evidenced by the highest scores received from tasters on the eighth day of storage. The study conducted by Quispe et al. in 2023 [26] also highlights the desire to consume camu-camu-enriched dairy products. For the control sample, the highest scores were recorded on the first day of analysis, with sensory characteristics being less appreciated during storage. The sensory evaluation of fresh cheese with different types of ingredients added to obtain or improve the product has been studied in the literature by various researchers. The majority of studies present a comparison between multiple samples, emphasizing their significance in achieving a nutritionally and qualitatively superior finished product [18,19,22,51]. Consequently, the incorporation of a flavoring agent into fresh cheese has been demonstrated to enhance its sensory characteristics.

3.4. Color Determination

The coloration of milk and cheese is attributable to the dispersion of fat globules and casein micelles under the influence of light [56]. In this study, the addition of camu-camu powder to fresh cheese resulted in a significant change in color (p < 0.05). However, the duration of storage had no significant effect on the color intensity of the samples (Figure 3).

With regard to the brightness of the samples of cheese with added camu-camu, different behaviors can be observed depending on the added powder concentration. It has been observed that as the percentage of camu-camu powder increases, the brightness of the cheese is concomitantly reduced. A decline in brightness was also observed over the 16-day period for the powdered samples. The control sample exhibited insignificant alterations during the storage period. The image displays a slight, nearly constant variation in brightness. A comparative analysis reveals that this sample exhibits a significantly higher degree of brightness in comparison to the other samples.

In regard to the measurement of color on the green-red axis, it is observed that the control sample remains constant around negative values, indicating that this sample is characterized by a very subtle hue of vision, undergoing slight changes over time. Concerning the b index, which measures the blue-yellow components in the product, it can be observed for the control sample that the index varies slightly in the yellow spectrum (10.468 ± 0.013 on day 1, 9.87 ± 0.01 on day 8, and 8.232 ± 0.0148 on day 16). The incorporation of 1% powder into the cheese led to products that exhibited a slight red tint, which diminished over time (0.33 ± 0.0122 on day 1, 0.87 ± 0.01 on day 8, 0.564 ± 0.0134 on day 16). However, the tints were predominantly yellow, and they intensified during storage (12.932 ± 0.0148 on day 1, 13.426 ± 0.0134 on day 8, and 13.272 ± 0.013 on day 16). Increasing the percentage of powder to 1.5% resulted in an intensification of red shades (1.36 ± 0.0187 on day 1, 1.824 ± 0.0182 on day 8, and 1.664 ± 0.0114 on day 16), but also an intensification of yellow shades (14.35 ± 0.0187 on day 1, 14.874 ± 0.0182 on day 8, and 14.564 ± 0.0152 on day 16). When 2% powder was used, an intensification of the red hue was measured over time (2.06 ± 0.01 on day 1, 2.462 ± 0.0083 on day 8, and 2.276 ± 0.00548 on day 16) and a more pronounced yellow hue compared to the other samples, but which lost its intensity over the 16 days (15.438 ± 0.0217 on day 1, 16.008 ± 0.00837 on day 8, and 15.85 ± 0.01 on day 18).

The yellow pigmentation is primarily attributed to the presence of carotenoids in fruits and vegetables. The majority of fruits exhibit higher concentrations of carotenoids in their skin compared to their flesh. The stability of the pigment is influenced by the method of processing the vegetable prior to its utilization, as well as the temperature and duration of the process [57]. The alterations in color resulting from the incorporation of diverse plant by-product powders into dairy products have also been corroborated by other researchers. Citrus peels were incorporated into the yogurt-making process, yielding a range of color variations in the resulting yogurts, as anticipated. An intensification of the yellow color was observed in the samples enhanced with mango peel powder compared to the samples enhanced with banana peel powder [58]. A study was conducted to investigate the effects of incorporating black carrot tescovine powder into yogurt, with concentrations ranging from 1% to 2%. The findings demonstrated that as the proportion of carrot powder in the yogurt increased, the L* value approached 0. This observation indicated a concomitant decrease in the brightness of the yogurt sample. The a* values were also found to be significantly modulated by the addition of black carrot powder. The predominant hue of these types of products is red, which is attributed to the conversion of anthocyanins at low pH values [59]. The addition of pumpkin powder to yogurt (2% and 4%) resulted in the production of yoghurts with a pronounced yellow hue. This phenomenon can be attributed to the presence of carotenoids and lutein, which are present in the pumpkin powder. These values underwent a decrease on day 14 of analysis, a phenomenon attributed to oxidation of β-carotene or other carotenoids present during storage [60,61].

The data show a tendency for the red and yellow shades in the cheese samples to increase in intensity with time, followed by a slight color degradation in the second storage period.

4. Conclusions

In summary, the present study demonstrates the positive effect of the addition of camu-camu powder to fresh cow’s cheese, a food with numerous benefits and recommended for regular consumption. The bioactive compounds present in the powder have been shown to have a positive influence on the antioxidant capacity of fresh cheese, with the 2% sample demonstrating the most effective antioxidant performance. From a sensory perspective, the 1.5% sample received the highest ratings from tasters. The 1% sample is distinguished by its notable colour stability during storage. The findings of the physicochemical analyses demonstrate that camu-camu powder can be a sustainable ingredient that enhances the quality of the finished product and prolongs its shelf life. This information is essential for evaluating the safety and efficacy of camu-camu powder in dairy products and may serve as a starting point for future studies. It is intended that this study will be continued, with the samples analysed from a textural, rheological and microbiological perspective (antimicrobial activity). Furthermore, there is an ambition to develop other food products with additional bioactive compounds using unconventional raw materials.