Selection of optimal ripening stage of papaya fruit (Carica papaya L.) and vacuum frying conditions for chips making

Figures & data

Figure 1. Papaya fruits (Carica papaya L., cv Pococí) at three ripening stages according to the percentage of skin yellowing: (a) batches of papaya fruits, (b) entire and halved fruits, (c) papaya chips obtained by vacuum frying. White bars mark 10 cm.

Figura 1. Papaya en tres estados de maduración según el porcentaje de color amarillo de la cáscara: (a) lotes de papaya fresca, (b) frutas enteras y en mitades, (c) chips de papaya obtenidos por fritura al vacío. Las barras blancas indican 10 cm

Figure 2. Sketch of the vacuum frying system used for obtaining the papaya chips: (a) basket in “bottom” position, (b) basket in “top” position.

Figura 2. Esquema del sistema de fritura al vacío utilizado para la obtención de los chips de papaya: (a) canasta en posición “inferior,” (b) canasta en posición “superior.”

Table 1. Physicochemical properties and carotenoid contents of papaya Pococí (Carica papaya L.) at three ripening stages.

Tabla 1. Propiedades fisicoquímicas y contenido de carotenoides en papaya Pococí (Carica papaya L.) en tres estados de maduración

	Fresh papaya – Ripening stage
Parameter	RS3	RS4	RS5
Moisture (g/100 g FW)^†	88.52 ± 0.82^a	88.04 ± 0.68^a	87.55 ± 0.91^a
Lipids (g/100 g FW)^†	ND	ND	ND
Protein (g/100 g FW)^†	0.57 ± 0.02^a	0.58 ± 0.03^a	0.50 ± 0.06^a
Ash (g/100 g FW)^†	0.47 ± 0.01^a	0.46 ± 0.03^a	0.47 ± 0.04^a
Dietary fiber (g/100 g FW)^†	1.79 ± 0.18^a	1.75 ± 0.09^a	1.66 ± 0.12^a
Glucose (g/100 g FW)^†	3.60 ± 0.01^a	4.07 ± 0.38^a	4.13 ± 0.25^a
Fructose (g/100 g FW)^†	3.52 ± 0.08^a	3.99 ± 0.33^a	4.06 ± 0.25^a
Sucrose (g/100 g FW)^†	ND	ND	ND
Citric acid (g/100 g FW)^†	0.095 ± 0.007^b	0.101 ± 0.002^ab	0.110 ± 0.001^a
Succinic acid (g/100 g FW)^†	0.045 ± 0.007^a	0.039 ± 0.002^a	0.035 ± 0.007^a
TSS (°Brix)^‡	12.17 ± 1.30^a	12.07 ± 0.65^a	11.75 ± 1.21^a
Skin firmness (N)^‡	33.07 ± 7.76^a	32.71 ± 6.81^a	24.45 ± 8.07^b
Pulp firmness (N)^‡	16.98 ± 6.18^a	11.89 ± 5.41^b	7.79 ± 2.92 ^c
Pulp color^‡:
L*	51.16 ± 2.39^a	47.80 ± 3.21^b	46.23 ± 3.02^b
C*	36.71 ± 2.22^b	37.5 ± 2.25^ab	38.78 ± 2.07^a
h°	55.82 ± 1.76^a	54.90 ± 2.24^a	55.19 ± 1.26^a
Carotenoids (mg/kg FW)^†:
all-E-β-cryptoxanthin	1.19 ± 0.31^a	1.86 ± 0.24^a	2.93 ± 0.81^a
all-E-β-cryptoxanthin-caprate	1.37 ± 2.22^b	2.17 ± 0.39^ab	3.03 ± 0.08^a
all-E-β-cryptoxanthin-laurate	3.92 ± 0.59^b	6.03 ± 1.13^ab	7.98 ± 0.17^a
all-E-β-cryptoxanthin-myristate	1.35 ± 0.25^b	1.84 ± 0.10^ab	2.29 ± 0.08^a
all-E-β-carotene	0.95 ± 0.01^c	1.94 ± 0.17^b	3.38 ± 0.11^a
all-E-lycopene	23.50 ± 2.12^b	31.43 ± 4.11^ab	34.98 ± 0.85^a
Z-lycopene	1.71 ± 0.36^a	1.81 ± 0.29^a	2.87 ± 1.24^a
Z-β-carotene	0.38 ± 0.17^a	1.06 ± 0.26^a	1.58 ± 0.53^a
Total β-cryptoxanthin	6.17 ± 0.49^b	9.43 ± 1.46^ab	12.92 ± 0.57^a
Total β-carotene	1.33 ± 0.17^c	3.00 ± 0.43^b	4.96 ± 0.42^a
Total lycopene	25.22 ± 2.48^a	33.24 ± 4.40^a	37.85 ± 2.09^a

^†Values are expressed as the mean ± standard deviation (n = 3). ^‡Values are expressed as the mean ± standard deviation (n = 25). FW, fresh weight. TSS, total soluble solids. ND, not detectable (lipids < 0.10 g/100 g; sucrose < 0.25 g/100 g). Means in the same row with the same letters are not significantly different from each other (Tukey’s test, p < 0.05).

^†Los valores son expresados como la media ± desviación estándar (n = 3). ^‡Los valores son expresados como la media ± desviación estándar (n = 25). FW, base fresca. TSS, sólidos solubles totales. ND, no detectable (lípidos < 0,10 g/100 g; sacarosa < 0,25 g/100 g). Los valores en la misma fila con las mismas letras no son significativamente diferentes entre sí (prueba de Tukey, p < 0.05).

Table 2. UV-Vis spectra of analyzed carotenoids in fresh papaya and papaya chips.

Tabla 2. Espectros UV-Vis de los carotenoides analizados en papaya fresca y en chips de papaya

No.	Retention time (min)	Carotenoid	Sample	HPLC-DAD UV-Vis spectrum (nm)	III/II (%)	AB/AII (%)
1	11.3	all-E-β-cryptoxanthin	FP, PC	(430), 452, 476	18	-
2	14.2	13Z-β-carotene	FP, PC	344, (422), 448, 466	9	44
3	17.2	all-E-β-carotene	FP, PC	(428), 450, 476	13	-
4	19.7	9Z-β-carotene	PC	336, (420), 446, 470	9	31
5	20.4	β-cryptoxanthin caprate	FP, PC	(430), 452, 476	17	-
6	22.7	β-cryptoxanthin laurate	FP, PC	(430), 452,476	18	-
7	25.7	β-cryptoxanthin myristate	FP, PC	(430), 452, 476	19	-
8	28.8	13Z-lycopene	FP, PC	362, 440, 466, 494	47	66
9	30.8	5Z-13ʹZ-lycopene	PC	360, 434, 458, 486	43	26
10	31.5	DiZ-lycopene	PC	362, 434, 458, 486	28	10
11	34.2	9Z-lycopene	FP, PC	362, 442, 466, 496	72	20
12	37.5	all-E-lycopene	FP, PC	446, 472, 502	74	-
13	37.7	5Z-lycopene	FP, PC	446, 472, 502	74	-

Values in bold represent the main maximum. Values in brackets mark point of inflection. III/II, ratio of the height of the longest-wavelength absorption peak (III) and that of the middle absorption peak (II), taking the minimum between the two peaks as baseline, multiplied by 100. A_B/A_II, ratio of the height of cis-peak (A_B) and that of the middle main absorption peak (A_II), multiplied by 100. FP, fresh papaya; PC, papaya chips.

Los valores en negrita representan el máximo principal de absorción. Los valores entre paréntesis marcan el punto de inflexión. III/II, relación de la altura del pico de absorción de longitud de onda más larga (III) y la del pico de absorción media (II), tomando el mínimo entre los dos picos como línea base, multiplicado por 100. A_B/A_II, relación de la altura del pico cis (A_B) y la del pico de absorción principal (A_II), multiplicado por 100. FP, papaya fresca; PC, chips de papaya.

Figure 3. HPLC separation of analyzed carotenoids monitored at 450 nm from: (a) fresh papaya, (b) papaya chips. For peak assignment, see Table 2.

Figura 3. Separación por HPLC de los carotenoides analizados y monitoreados a 450 nm: (a) papaya fresca, (b) chips de papaya. Para la asignación de picos, consultar la Table 2

Table 3. Physicochemical properties and sensory acceptance of vacuum-fried papaya chips, and yield process according to each ripening stage of papaya Pococí (Carica papaya L.).

Tabla 3. Propiedades fisicoquímicas y aceptación sensorial de chips de papaya fritos al vacío, y rendimiento del proceso según cada estado de maduración de papaya Pococí (Carica papaya L.)

	Papaya chips – Ripening stage
Parameter	RS3	RS4	RS5
Moisture (g/100 g FW)	1.48 ± 0.42^a	1.41 ± 0.24^a	1.18 ± 0.16^a
Lipids (g/100 g FW)	31.86 ± 1.79^a	36.62 ± 3.90^a	30.77 ± 1.23^a
aw	0.186 ± 0.016^a	0.187 ± 0.017^a	0.195 ± 0.001^a
Color parameters:
L*	54.09 ± 4.60^a	47.13 ± 2.58^ab	45.13 ± 1.59^b
C*	54.37 ± 2.23^a	49.93 ± 1.87^ab	48.80 ± 1.24^b
h°	63.37 ± 2.11^a	60.84 ± 0.40^ab	59.97 ± 1.30^b
∆E	19.72 ± 3.71^a	13.94 ± 3.71^ab	11.10 ± 1.42^b
BI	200.16 ± 11.11^a	212.90 ± 11.11^a	216.97 ± 0.38^a
Overall sensory acceptance^†	5.9 ± 0.5^b	6.5 ± 0.4^a	6.6 ± 0.4^a
Process yields (%):
Peeling+deseeding+slicing	79.47 ± 1.20^a	75.77 ± 1.53^a	68.42 ± 4.67^b
Frying	17.23 ± 0.57^b	19.36 ± 1.15^a	14.64 ± 0.29^c
Overall	13.69 ± 0.45^a	14.67 ± 0.87^a	10.02 ± 0.20^b

Values are expressed as the mean ± standard deviation (n = 3, ^†n = 100). ∆E, color difference; BI, browning index. FW, fresh weight. Means in the same row with the same letters are not significantly different from each other (Tukey’s test, p < 0.05).

Los valores son expresados como la media ± desviación estándar (n = 3, ^†n = 100). ∆E, diferencia de color; BI, índice de pardeamiento. FW, base fresca. Los valores en la misma fila con las mismas letras no son significativamente diferentes entre sí (prueba de Tukey, p < 0.05).

Table 4. Two factor-five level central composite design and experimental data for the responses.

Tabla 4. Diseño compuesto central de dos factores y cinco niveles y datos experimentales para las respuestas

Standard order	Run order	X1	X2	Y1, moisture	Y2, aw	Y3, lipids	Y4, ∆E	Y5, BI
1	8	105.86 (−1)	9.88 (−1)	1.69	0.270	22.58	30.61	227.35
2	3	105.86 (−1)	14.12 (+1)	1.19	0.219	28.94	24.83	195.24
3	2	134.14 (+1)	9.88 (−1)	0.92	0.210	25.92	17.88	162.97
4	11	134.14 (+1)	14.12 (+1)	0.50	0.186	30.20	14.83	167.19
5	7	100.00 (−1.414)	12.00 (0)	2.25	0.262	20.57	31.92	212.06
6	10	140.00 (+1.414)	12.00 (0)	0.45	0.228	33.48	21.08	167.36
7	6	120.00 (0)	9.00 (−1.414)	1.13	0.259	28.01	26.36	164.41
8	4	120.00 (0)	15.00 (+1.414)	0.49	0.201	39.43	11.45	180.03
9	9	120.00 (0)	12.00 (0)	1.15	0.177	29.40	17.90	164.56
10	5	120.00 (0)	12.00 (0)	1.21	0.180	30.06	15.13	171.25
11	1	120.00 (0)	12.00 (0)	1.39	0.198	27.85	17.07	171.56

X₁, temperature (°C); X₂, time (min); Y₁ moisture content (g/100 g fresh weight); Y₂, water activity (a_w); Y₃, lipid content (g/100 g dry weight); Y₄, color difference (∆E); Y₅, browning index (BI).

X₁, temperatura (° C); X₂, tiempo (min); Y₁ contenido de humedad (g/100 g base fresca); Y₂, actividad del agua (a_w); Y₃, contenido de lípidos (g/100 g base seca); Y₄, diferencia de color (∆E); Y₅, índice de pardeamiento (BI).

Table 5. Regression coefficients and analysis of the model for response variables.

Tabla 5. Coeficientes de regresión y análisis del modelo para las variables respuesta

	Predicted values
Regression coefficients	Moisture	aw	Lipids	∆E	BI
β0	1.313***	0.185**	30.462***	17.581**	172.281****
β1	−0.501**	−0.018*	2.857*	−4.758*	−19.456**
β2	−0.228*	−0.020*	3.349*	−3.739*	-
β11	-	0.026*	−2.331*	4.458*	11.113*
β22	−0.246*	0.018*	-	-	-
β12	-	-	-	-	9.083*
R^2	0.943	0.892	0.739	0.917	0.869
R^2-adj	0.918	0.819	0.628	0.882	0.813
p value of model	<0.0001	0.005	0.019	<0.0001	0.002
p value of lack of fit	0.237	0.388	0.094	0.249	0.121
MS of pure error	0.030	0.000	12.782	6.667	118.142
MS of lack of fit	0.009	0.000	1.288	2.027	15.656

∆E, color difference; BI, browning index. *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001.

∆E, diferencia de color; BI, índice de pardeamiento. *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001.

Figure 4. Response surface plots for moisture (a), a_w (b), lipids, dry weight (c), color difference (d) and browning index (e) as function of temperature and time of vacuum frying.

Figura 4. Gráficos de superficie de respuesta para humedad (a), a_w (b), lípidos, base seca (c), diferencia de color (d) e índice de pardeamiento (e) en función de la temperatura y el tiempo de fritura al vacío

Table 6. Experimental and predicted values of responses under optimum vacuum frying conditions.

Tabla 6. Valores experimentales y predichos de las variables respuesta en las condiciones óptimas de fritura al vacío

	Responses
Optimum point^a	Moisture (g/100 g)	aw	Lipids (g/100 g, DW)	ΔE	BI
Experimental value^b	1.90 ± 0.55	0.170 ± 0.025	29.82 ± 1.83	15.43 ± 2.66	171.89 ± 8.73
Predicted value^c	1.14 ± 0.28	0.180 ± 0.043	32.14 ± 2.91	15.71 ± 3.66	172.28 ± 7.15

∆E, color difference; BI, browning index. ^aOptimum point: temperature, 120 °C and time, 13.1 min. ^bResults are expressed as the mean ± confidence interval at 95% confidence level for n = 3. ^cResults are expressed as the mean ± confidence interval at 95% confidence level. DW, dry weight.

∆E, diferencia de color; BI, índice de pardeamiento. ^aPunto óptimo: temperatura, 120 °C y tiempo, 13,1 min. ^bLos resultados son expresados como la media ± intervalo de confianza al nivel de confianza del 95% para n = 3. ^cLos resultados son expresados como la media ± intervalo de confianza al nivel de confianza del 95%. DW, base seca.

Table 7. Physicochemical properties and carotenoid contents of papaya Pococí (Carica papaya L.) at RS4 and papaya chips obtained at optimum vacuum frying conditions.

Tabla 7. Propiedades fisicoquímicas y contenido de carotenoides en papaya Pococí RS4 (Carica papaya L.) y en chips de papaya obtenidos en condiciones óptimas de fritura al vacío

Parameter	Fresh papaya (RS4)	Papaya chips
Moisture (g/100 g FW)	88.04 ± 0.68	1.90 ± 0.48
Lipids (g/100 g FW)	ND	29.25 ± 1.53
Protein (g/100 g FW)	0.58 ± 0.03	3.34 ± 0.62
Ash (g/100 g FW)	0.46 ± 0.03	3.23 ± 0.48
Dietary fiber (g/100 g FW)	1.75 ± 0.09	14.10 ± 0.09
Total sugars (g/100 g FW)	8.06 ± 0.71	42.87 ± 1.55
aw	0.987 ± 0.001	0.170 ± 0.025
Color parameters:
L*	47.84 ± 6.71^†	50.81 ± 2.92
C*	37.52 ± 6.01^†	45.81 ± 1.18
h°	54.93 ± 4.07^†	67.44 ± 1.42
∆E	-	15.43 ± 2.35
BI	-	171.89 ± 7.71
Carotenoids (mg/kg FW):
all-E-β-cryptoxanthin	1.86 ± 0.24	4.32 ± 0.55
all-E-β-cryptoxanthin-caprate	2.17 ± 0.39	5.55 ± 1.00
all-E-β-cryptoxanthin-laurate	6.03 ± 1.13	19.60 ± 3.66
all-E-β-cryptoxanthin-myristate	1.84 ± 0.10	3.20 ± 0.18
all-E-β-carotene	1.94 ± 0.17	6.75 ± 0.60
all-E-lycopene	31.43 ± 4.11	264.44 ± 34.60
Z-lycopene	1.81 ± 0.29	77.97 ± 12.40
Z-β-carotene	1.06 ± 0.26	8.92 ± 1.67
Total β-cryptoxanthin	9.43 ± 1.46	22.98 ± 3.57
Total β-carotene	3.00 ± 0.43	15.67 ± 2.26
Total lycopene	33.24 ± 4.40	342.41 ± 47.00

Values are expressed as the mean ± standard deviation (n = 3, ^†n = 25). ∆E, color difference; BI, browning index. FW, fresh weight.

Los valores son expresados como la media ± desviación estándar (n = 3, ^†n = 25). ∆E, diferencia de color; BI, índice de pardeamiento. FW, base fresca.

Figure 5. Experimental data for vacuum-fried papaya chips and predicted sorption isotherm using GAB equation at 25 °C. M_g, C and K are the parameters obtained from GAB equation (see Section 2.11), the standard error for these parameters is expressed in brackets (n = 5).

Figura 5. Datos experimentales para chips de papaya fritos al vacío e isoterma de sorción predicha utilizando la ecuación GAB a 25 °C. M_g, C y K son los parámetros obtenidos de la ecuación GAB (ver sección 2.11), el error estándar para estos parámetros se expresa entre paréntesis (n = 5)

Figure 6. Carotenoid concentrations in fresh papaya and papaya chips. Bars are expressed as the mean ± standard deviation (n = 3). For each carotenoid means with the same letter are not significantly different (Student’s t-test, p < 0.05). RS4, ripening stage 4; NF-DW, non-fat dry weight. BCX, all-E-β-cryptoxanthin, sum of free and esters forms; BC, all-E-β-carotene; LYC, all-E-lycopene; Z-BC, Z-β-carotene; Z-LYC, Z-lycopene.

Figura 6. Concentración de carotenoides en papaya fresca y chips de papaya. Las barras se expresan como la media ± desviación estándar (n = 3). Para cada carotenoide, los valores con la misma letra no son significativamente diferentes (prueba t de Student, p < 0,05). RS4, etapa de maduración 4; NF-DW, base seca no grasa. BCX, all-E-β-criptoxantina, suma de formas libres y ésteres; BC, all-E-β-caroteno; LYC, all-E-licopeno; Z-BC, Z-β-caroteno; Z-LYC, Z-licopeno