Characterization and stability of pitaya pearls from hydrocolloids by reverse spherification

Figures & data

Table 1. Formulation of pitaya pearls by using different hydrocolloids

	Pitaya pearls*
Ingredients	Alginate	Kappa	Iota Alginate
Pearl solution
Pitaya puree (g)	500	500	500
Calcium chloride (g)	4	4	4
Bath solution
Distilled water (mL)	100	100	100
Sodium alginate (g)	5	-	2
Kappa carrageenan (g)	-	5	-
Iota carrageenan (g)	-	-	3

* Pitaya pearls produced using bath solutions of sodium alginate, kappa carrageenan and combination of sodium alginate-iota carrageenan.

Table 2. Nutritional compositions and calorie of pitaya pearls

	Pitaya pearls*
	Alginate	Kappa	Iota Alginate
Moisture (%)	94.17 ± 1.66^a	95.60 ± 0.15^a	95.53 ± 0.02^a
Protein (%)	0.17 ± 0.15^a	0.26 ± 0.26^a	0.17 ± 0.15^a
Fat (%)	0.02 ± 0.03^a	0.06 ± 0.10^a	0.11 ± 0.19^a
Ash (%)	0.82 ± 0.37^a	0.35 ± 0.03^b	0.31 ± 0.09^b
Calorie (kcal)	17.64	12.86	15.35

Data are means ± standard deviation. Means within columns not sharing a common letter are significantly different at p ≤ .05.

* Pitaya pearls produced using bath solutions of sodium alginate, kappa carrageenan and combination of sodium alginate-iota carrageenan.

Table 3. Size and texture profiles of pitaya pearls

	Pitaya pearls*
Parameter	Alginate	Kappa	Iota Alginate
Size (mm)	4.87 ± 0.23^b	5.15 ± 0.09^b	7.75 ± 1.22^a
Hardness (g)	255.66 ± 16.21^a	147.72 ± 13.11^b	148.10 ± 6.49^b
Cohesiveness	0.41 ± 0.05^a	0.27 ± 0.01^b	0.28 ± 0.004^b
Gumminess (g)	105.91 ± 16.17^a	41.51 ± 5.01^b	40.86 ± 1.23^b
Springiness (mm)	0.39 ± 0.02^c	0.79 ± 0.01^a	0.47 ± 0.02^b
Rupture force (g)	47.62 ± 12.13^b	24.22 ± 5.03^c	73.11 ± 6.26^a
Elasticity (mm)	1.38 ± 0.16^a	1.53 ± 0.16^a	0.97 ± 0.02^b

Data are means ± standard deviation. Means within columns not sharing a common letter are significantly different at p ≤ .05.

* Pitaya pearls produced using bath solutions of sodium alginate, kappa carrageenan and combination of sodium alginate-iota carrageenan.

Figure 1. Microstructure of pitaya pearls (PP) at day 0 under a digital microscope at 40, 200 and 400 × magnifications

Figure 2. Microstructure of pitaya pearls (PP) after 4-days storage at −24°C observed under a scanning electron microscope at 30 and 300 × magnifications

Table 4. Colour attributes of pitaya pearls

	Pitaya pearls^#
	Alginate	Kappa	Iota Alginate
L* (Lightness)	19.97 ± 1.44^a	18.30 ± 0.21^a	18.71 ± 0.39^a
a* (Redness)	15.84 ± 0.80^a	8.69 ± 0.31^b	14.70 ± 0.90^a
b* (Blueness)	−3.28 ± 0.43^a	−4.40 ± 0.30^b	−3.85 ± 0.24^ab

Data are means ± standard deviation. Means within columns not sharing a common letter are significantly different at p ≤ .05.

^# Pitaya pearls produced using bath solutions of sodium alginate, kappa carrageenan and combination of sodium alginate-iota carrageenan.

Table 5. Storage variables (temperature, duration, and formula) effect on rupture force, elasticity and moisture content of pitaya pearls

			Main effect								Interacted effect
Parameters	Temperature (°C)		Duration (day)					Formula^#			Formula & Temperature	Formula & Duration	Temperature & Duration	Formula & Duration & Temperature
	4	−24	0	1	2	3	4	A	K	IA
Rupture force
Mean (g)	38.25	52.12	46.17	48.27	34.42	40.36	56.69	49.45	43.51	42.58
P-value	0.00		0.00					0.20			0.31	0.00	0.12	0.00
R-squared														68.08
Elasticity
Mean (mm)	1.37	1.08	1.19	1.37	1.08	1.10	1.39	1.40	1.27	1.01
P-value	0.00		0.00					0.00			0.00	0.00	0.00	0.00
R-squared														82.30
Moisture
Mean (%)	91.59	90.65	94.16	-	92.17	-	87.04	91.52	92.10	89.75
P-value	0.42		0.00					0.24			0.11	0.69	0.98	0.03
R-squared														58.02

The main effect and interacted effect variables are significantly different when p-value is <.05.

^# Pitaya pearls produced using bath solutions of sodium alginate (A), kappa carrageenan (K) and combination of sodium alginate and iota carrageenan (IA).