Fruit dehydration is a way of supplying the population with healthy and nutritious foods. The shelf life of dried fruit can be defined by the evaluation of changes occurred in chemical characteristics during storage. This study aims to evaluate the sensory quality and the stability of papaya cv. Tainung n ° 1 dehydrated by convective drying. Fresh and dried papaya were evaluated for color, moisture, pH, acidity, water activity, soluble solids, vitamin C, carotenoids, total extractable polyphenols (TEP) and antioxidant activity (ABTS). The sensorial acceptance of the dried papaya was evaluated using a structured nine-point hedonic scale. For the stability study, the analysis of moisture, pH, titratable acidity, water activity, total carotenoids and vitamin C were carried out every 30 days of storage until 120 days. During storage, the moisture content of dried papaya remained constant, but there were undesirable changes in color, increase of acidity and reduction of soluble solids. The degradation of total carotenoids and vitamin C followed the first order reaction, and the half-life time was 346 days for carotenoids, whereas for vitamin C it was only 29 days. In the sensory analysis, the dried papaya received grades between 5.0 and 6.0 for all evaluated attributes. Dried papaya is recommended to be consumed up to 30 days, since within this period a product with higher total carotenoids content, vitamin C and with satisfactory physicochemical and sensorial characteristics were obtained.
The pulp of papaya (Carica papaya L.) has a pleasant aroma and taste, which are important qualities for sensorial acceptance for people of all ages. This fruit also presents interesting nutritional characteristics that include it in the select group of healthy foods. The chemical composition of papaya is in concordance with the cultivar, climate, cultural treatments and maturation stage. The Tainung n˚ 1 variety presents, in 100 g of pulp, 45 kcal; 11.06% carbohydrate; 25 mg of calcium; 17 mg of magnesium; 222 mg potassium; and 78.5 mg of vitamin C [
Papaya is also an important source of carotenoids (β-carotene, lycopene and β-cryptoxanthin) and phenolic (myricetin, fisetin, morin, quercetin, kaempferol and isorametina) [
It is consumed preferentially fresh, but is a highly perishable fruit. It is estimated that losses occurring in the field, transportation and storage are 25% [
Among the various conservation methods, drying is a relatively simple process in which water activity in food is reduced, minimizing or inhibiting the chemical and enzymatic reactions and microbial growth that are responsible for its deterioration [
During the fruit drying process, changes in appearance and color may occur and compromise the product acceptance. These changes occur through the action of the polyphenol oxidases enzymes that are present in the fruits, leading to the formation of melanins (dark pigments) from the oxidation of phenols to o-quinones [
Loss of nutrients, such as vitamin C and carotenoids, may occur during storage, thus reducing the nutritional value of dried fruit. Degradation of these nutrients depends on factors such as pH, oxygen exposure, presence of light, metals, enzymes, temperature and the drying methods used [
In addition to the nutritional aspects, sensorial attributes must be evaluated in order to determine the quality of dried fruits. The aroma and flavor may be altered due to loss of volatiles during drying and storage of the dried fruits, leading to lower product acceptance [
The objective of this study was to evaluate the physicochemical characteristics, bioactive compounds, sensory acceptance and the stability of dried papaya obtained by convective drying.
Papaya (Carica papaya L.) fruits of Tainung n˚ 1 variety were purchased in local market and processed at maturity stage 4 (bark surface 50% to 75% yellow). The fruits were washed in water and immersed in solution with 100 mg/L of chlorine for 15 minutes. Fruits were peeled, the seeds removed and cut crosswise into 1.2 cm thick slices.
The slices were subdivided into pieces of 3.0 × 3.0 cm and submitted to the following treatments: T1―control treatment (without antioxidant treatment); T2―papaya immersion in solution containing 25 mg/L citric acid + 75 mg/L of ascorbic acid for 10 minutes, according to Reis et al. [
The papaya slices (T1 and T2) were dehydrated at 60˚C in a dryer with fixed air velocity of 1.5 m/s until reaching final humidity between 15% and 25% (w.b). The dried papayas were packed in polyethylene terephthalate/aluminum/polyethylene (PET/Al/PE) and stored for 120 days at room temperature (28˚C ± 2˚C).
The fresh and dried papayas were evaluated for color, moisture, pH, titratable acidity (TA), water activity (aw) and soluble solids (SS).
The color was determined using the colorimeter (Konica Minolta, model CR400, CIELAB system, illuminant D65). A sample of ten pieces of each treatment was analyzed. The coordinates L* (lightness), a* (green/red intensity) and b* (blue/yellow intensity) and the color attributes C* (color intensity/chroma) and h* (hue/color angle). The color variation (ΔE*) was also calculated by the Equation (1) [
Δ E * = [ ( L 0 * − L * ) 2 + ( a 0 * − a * ) 2 + ( b 0 * − b * ) 2 ] 1 / 2 (1)
The analysis of moisture, pH, soluble solids and titratable acidity were performed according to the Adolfo Lutz Institute [
The total carotenoid contents were determined according to Rodriguez-Amaya and Kimura [
The content of vitamin C was determined by the reaction of ascorbic acid with 2.6-dichlorophenol indophenol (DCFI), according to the procedure described by Oliveira [
For the determination of TEP and antioxidant activity, papaya extracts were prepared as described by Larrauri et al. [
The total antioxidant activity was determined by capture of the radical ABTS+ according the methodology proposed by RE et al. [
The color, moisture, pH, titratable acidity, water activity, total carotenoids and vitamin C were determinated at zero time and every 30 days of storage for a period of 120 days for the stability of the dried papaya. Degradation of the total carotenoids and vitamin C during storage followed the first-order reaction, and the data were evaluated using the following model:
C = C 0 e − k t
where C 0 in C that represent component concentrations at zero and t time, respectively, and k is the reaction rate constant (time−1).
The study was approved by the Research Ethics Committee of Maria Milza College, located in Governador Mangabeira, Bahia, Brazil (authorization n˚ 246/11). The sensory test was performed in individual cabins under white light by fifty not trained judges, with age between 18 and 60 years. The tests were carried out at 30-day storage. The acceptance test was made using a structured 9-points hedonic scale, in which 1 represents “dislike extremely” and 9 represents “like extremely”. The attributes intensity of color, aroma, flavor and texture were evaluated using a nine-point intensity scale as described in Meilgaard et al. [
All drying processes and all analysis were repeated three times. The one-way analysis of variance (ANOVA) was used to compare the two treatments of dried papaya (T1 and T2) at 5% significance level, by F test. Results were expressed as mean ± standard deviation.
The study of stability was performed in the completely randomized design in a split plot system. Two treatments (T1 and T2) constituted the plots and five storage times (0, 30, 60, 90, 120 days) constituted the subplots. The data were analyzed by ANOVA at 5% significance level and regression analysis using Sisvar and R programs.
The results of characterization of fresh and dried papaya (zero storage time) were shown in
Physicochemical Characteristics | Fresh Papaya | Dried Papaya | ||
---|---|---|---|---|
T1(1) | T2(2) | Average(3) | ||
Humidity (%) | 88.82 ± 0.85 | 20.06 ± 5.89a | 26.78 ± 4.71a | 23.42 ± 4.75 |
Titratable acidity, TA (% citric acid) | 0.10 ± 0.01 | 0.94 ± 0.04a | 0.83 ± 0.09a | 0.89 ± 0.08 |
pH | 5.11 ± 0.13 | 5.15 ± 0.17a | 4.98 ± 0.22a | 5.06 ± 0.12 |
Soluble solids, SS (˚Brix) | 10.78 ± 0.55 | 156.43 ± 26.01a | 123.92 ± 21.94a | 140.18 ± 22.98 |
SS/TA | 106.69 ± 14.02 | 166.47 ± 26.76a | 150.44 ± 33.12a | 158.46 ± 11.34 |
aw | 0.94 ± 0.02 | 0.55 ± 0.03a | 0.58 ± 0.09a | 0.57 ± 0.02 |
Total carotenoids (µg/g) | 36.38 ± 1.61 | 219.99 ± 7.25a | 218.92 ± 20.95a | 219.46 ± 0.76 |
Vitamin C (mg/100g) | 53.84 ± 4.88 | 375.54 ± 18.27a | 269.96 ± 66.92a | 322.61 ± 74.85 |
TEP (mg GAE/100g) | 47.04 ± 1.17 | 274.70 ± 107.80a | 263.50 ± 91.13a | 269.09 ± 7.92 |
ABTS (µM trolox/g) | 4.35 ± 0.34 | 8.27 ± 2.69a | 7.44 ± 2.58a | 7.86 ± 0.59 |
L* | 53.68 ± 2.38 | 55.08 ± 6.00a | 51.35 ± 4.43a | 53.22 ± 2.64 |
a* | 26.85 ± 0.48 | 37.35 ± 1.46a | 35.52 ± 3.71a | 36.44 ± 1.30 |
b* | 41.88 ± 2.36 | 49.98 ± 6.66a | 47.79 ± 4.29a | 48.89 ± 1.54 |
C* | 49.92 ± 1.86 | 62.68 ± 5.34a | 59.79 ± 5.22a | 61.24 ± 2.04 |
h* | 57.29 ± 1.79 | 52.97 ± 3.82a | 52.99 ± 1.02a | 52.98 ± 3.82 |
ΔE* | - | 11.69 ± 0.74a | 12.51 ± 2.60a | 12.10 ± 0.60 |
Means followed by the same letter in the same row are not significantly different (p > 0.05) by F test. (1)Control Treatment; (2)Immersion in aqueous solution containing 25 mg/L citric acid + 75 mg/L ascorbic acid for 10 minutes. (3)Average values of treatments T1 and T2; aw: water activity; TEP: total extractable polyphenols; ABTS = antioxidant activity by the ABTS method; ΔE * = total variation of color dried papaya compared to fresh papaya.
After drying process, the solids and organic acids of papaya were concentrated. The SS/TA increased 48.52%, which may positively influence in the acceptance of the dried papaya by consumers, since products with higher SS/TA have more pronounced sweetness. There were also increased levels of bioactive compounds in dried papaya, where values were approximately six times higher than those presented in fresh one. The increase in concentration of these compounds, promoted the increase of its antioxidant activity, which passed from 4.35 for fresh to 7.86 μM trolox/g for dried papaya (T1 and T2 average) (
The use of the citric acid and ascorbic acid combination did not have a significant effect (p > 0.05) on coloration of dried papaya (
The total color variation, ΔE*, was 12.10 (
When comparing the contents of the bioactive compounds on dry basis (
Bioactive compounds | Fresh Papaya | Dried Papaya | % Degradation(4) | % Retention(5) | ||
---|---|---|---|---|---|---|
T1(1) | T2(2) | Average(3) | ||||
TEP (mg GAE/100g) | 422.01 ± 26.72 | 338.31 ± 111.07a | 356.40 ± 106.18a | 347.36 ± 12.79 | 17.69 | 82.31 |
Vitamin C (mg/100g) | 481.23 ± 8.37 | 471.53 ± 42.33a | 365.63 ± 72.45a | 418.58 ± 74.88 | 13.02 | 86.98 |
Carotenoids (µg/g) | 329.53 ± 4.00 | 264.79 ± 17.25a | 305.23 ± 5.92a | 285.00 ± 28.59 | 13.51 | 86.95 |
ABTS (µM trolox/g) | 39.12 ± 5.22 | 10.42 ± 3.60a | 10.32 ± 4.18a | 10.37 ± 0.07 | - | - |
Means followed by the same letter in the same row are not significantly different (p > 0.05) by F test. (1)Control Treatment; (2)Immersion in aqueous solution containing 25 mg/L citric acid + 75 mg/L ascorbic acid for 10 minutes; (3)Average values of treatments T1 and T2; (4)Calculated for average value of treatment T1 and T2 in relation of fresh papaya; (5)Calculated by difference between 100 and the % of degradation.
from 7% to 69% for phenolic content, and the dried product had contents from 84.78 to 250 mg GAE/100g, lower values than the results of this study.
Degradation of vitamin C during the drying process was only 13.02% (
For carotenoids, the drying process employed promoted the 13.51% degradation. Factors such as high temperature, presence of light, oxygen, acids and metals can promote the degradation of these pigments during the drying process. However, Udomkun et al. [
The stability of the dried papaya during storage can be observed in Figures 1-3. No significant difference (p > 0.05) was observed between the control treatments (T1) and with addition of 25 mg/L citric acid + 75 mg/L ascorbic acid (T2) during storage. However, the physicochemical caracteristics of dried papaya changed significantly (p < 0.05) during the storage (
Dried papaya moisture remained constant during storage, with a mean value of 23.20%, but water activity increased to 0.64 (
The dried papaya darkened during storage, probably due to the Maillard reaction, a fact that can be observed by the reduction in L* values (
The coordinates a* and b* and the C* attribute also reduced significantly (p < 0.05) and the papaya presented a less intense reddish coloration (Figures 2(b)-(d)) after 120 days. On the other hand, the value of h* remained constant during storage (data not shown). The reduction of these coordinates occurred due to the carotenoids degradation, since the papaya color is the result of β-carotene, α-carotene, cryptoxanthin and lycopene presence.
Degradation of the total carotenoids during storage followed the first-order reaction (
Vitamin C is often used as a quality index during food processing and storage [
There was no significant difference (p > 0.05) between the two treatments (T1 and T2) regarding sensorial acceptance (
Attributes | Acceptance Test(1) | Attribute Intensity(2) | ||||
---|---|---|---|---|---|---|
T1(3) | T2(4) | Average(5) | T1(3) | T2(4) | Average(5) | |
Color | 5.82 ± 1.79a | 5.34 ± 2.03a | 5.58 ± 0.34 | 6.18 ± 1.77a | 6.66 ± 1.98a | 6.42 ± 0.34 |
Aroma | 6.12 ± 1.61a | 5.44 ± 1.51a | 5.78 ± 0.48 | 5.04 ± 2.05a | 5.48 ± 2.18a | 5.26 ± 0.31 |
Flavor | 5.42 ± 1.95a | 5.94 ± 1.88a | 5.68 ± 0.37 | 5.30 ± 1.90a | 5.42 ± 1.99a | 5.36 ± 0.08 |
Texture | 4.90 ± 2.17a | 5.34 ± 2.22a | 5.12 ± 0.31 | 6.82 ± 1.73a | 6.20 ± 1.67a | 6.51 ± 0.44 |
Overall | 5.70 ± 1.78a | 5.36 ± 1.84a | 5.53 ± 0.24 | - | - | - |
Means followed by the same letter in the same row are not significantly different (p > 0.05) by F test. (1)mean hedonic score (n = 50) according nine-point scale, with the terms “dislike extremely” (1) and “like extremely” (9). (2)Attribute intensity according to nine-point scale: very light color (1) to very dark (9); weak aroma (1) to strong aroma (9); weak flavor (1) to strong flavor (9); very soft texture (1) very hard texture (9). (3)Control Treatment; (4)Immersion in aqueous solution containing 25 mg/L citric acid + 75 mg/L of ascorbic acid for 10 minutes. (5)Average of treatments T1 and T2.
intermediate and the dried papaya was classified as “neither like nor dislike” and “liked slightly”. A similar result was obtained Canizares and Mauro [
Regarding intensity scale, dried papaya was considered dark (6.42), a fact confirmed by the values of C*, h*, a* and ΔE (
The degradation of total carotenoids and vitamin C followed the first order reaction, and the half-life time was 346 days for carotenoids and 29 days for vitamin C.
After 120 days of storage, the dried papaya darkened and presented less intense reddish coloration. The vitamin C content reduced 94% and the total carotenoids content reduced 21%.
Sensory acceptance was intermediate and the dried papaya was classified as “neither like nor dislike” and “liked slightly”. The aroma and taste were considered intermediate (neither strong nor weak) and the dried papaya presented a hard texture.
Dried papaya must be consumed within 30 days of storage to be considered a good nutritional quality product.
To the Brazilian Agricultural Research Corporation (Embrapa), the National Council for Scientific and Technological Development (CNPq), and the Foundation for Research Support of the State of Bahia (Fapesb), for financial support.
Reis, R.C., Viana, E.S., da Silva, S.C.S., Mamede, M.E.O. and Araújo, Í.M.S. (2018) Stability and Sensory Quality of Dried Papaya. Food and Nutrition Sciences, 9, 489-501. https://doi.org/10.4236/fns.2018.95038