Lactobacillus acidophilus and Bifidobacterium spp. (Vivolac, Mexico) were reactivated in Man Rogosa Sharpe (MRS) broth supplemented with 0.05 % (w/v) cysteine, and incubated at 38 °C for 20 h. Subsequently, cells were centrifuged at 4500 rpm for 15 min, at 4 °C. The pellet containing the cells was washed twice with 0.9 % (w/v) saline solution and centrifuged using the same conditions (Odila et al., 2016).

The green coffee beans were ground and then passed in a sieve 40 (0.420 mm) to produce green coffee powder. To obtain the green coffee extract, the methodology of Budryn et al. (2013) was employed with some modifications. Briefly, the green coffee powder was mixed with distilled water at a 1:5 (w/v) ratio and heated at 90 °C for 1 h. Subsequently, the solution was filtered using filter paper (0.16 mm pore size). Finally, the green coffee extract (GCE) was stored in amber jars at 4 °C until use.

The double microencapsulation of microorganisms and coffee extract was performed following the methodology proposed by Flores-Belmont et al. (2015), with some modifications. In the first step, an aqueous of gelatin-maltodextrin (1:25) solution, at 26 % (w/w), was prepared in an ascorbic acid solution at 1 % (w/v). The GCE was added to a final concentration of 4.2 mg gallic acid equivalent/mL. Lactobacillus acidophilus and Bifidobacterium spp. were added to a final concentration of 10⁹ and 10⁸ CFU/mL, respectively. Subsequently, the mixture was homogenized using an Ultra Turrax T-25 Basic Homogenizer at 4500 rpm for 5 min. The mixture was fed into a spray dryer (BUCHI Mini B-290, Flawil, Switzerland) at a constant flow of 14 mL/min, and two inlet air temperatures, 120 °C and 140 °C, were evaluated, with an outlet air temperature of 50 °C. The microcapsules obtained in the first spray-dried process were hydrated and dried by spray drying in a second step. For this, 10 g of the microcapsules were added to 100 mL of a 0.5 % (w/v) chitosan solution prepared in 1 % (v/v) acetic acid, and the mixture was subjected to the drying process following the same conditions as the first step. Finally, the microcapsules were stored in vacuum-sealed metal bags until use.

The microencapsulation efficiency of probiotic microorganisms (MEP) was evaluated using one gram of the suspension before drying or one gram of the microcapsules which were mixed with 9 mL of sterile peptone water (0.1 %, w/v). Viable cell counts were determined in triplicate by plate seeding using MRS agar supplemented with L-cysteine (0.05 % w/v) and incubated at 37 °C (72 h). Previous results showed that the morphology of colonies was different for Lactobacillus acidophilus and Bifidobacterium spp. The results were expressed as a log CFU/g sample as suggested by Pupa et al. (2021). The MEP was calculated by equation1:

M E P   % = ( N / N o ) × 100 (1)

where No and N represented the log of the number of viable cells (CFU) before and after the encapsulation process, respectively.

After simple and double spray drying, microcapsules were characterized in terms of water solubility index (WSI), water absorption rate (WAR), swelling capacity (SC), morphology, microencapsulation efficiency of phenolic compounds (MYp) and antioxidant activity (AA).

The WSI was determined according to Paini et al. (2015). One gram of the microcapsules was mixed with 12 mL of distilled water, mixed and incubated at 30 °C for 30 min. The sample was then centrifuged at 3500 rpm for 10 min. The supernatant was transferred to a capsule and dried at 105 °C until it reached a constant weight. The WSI, WAR, and SC were calculated using equations 2, 3, and 4, respectively:

W S I % = S u p e r n a t a n t   d r i e d   w e i g h t I n i t i a l   w e i g h t   m i c r o c a p s u l e s × 100 (2)

W A R g ∕ g = F r e s h   s e d i m e n t   w e i g h t I n i t i a l   w e i g h t   m i c r o c a p s u l e s (3)

S C   g ∕ g = S u p e r n a t a n t   d r i e d   w e i g h t I n i t i a l   w e i g h t   m i c r o c a p s u l e s   ( 100 - W S I ) (4)

The morphology of the microcapsules was examined by scanning electron microscopy (SEM) using a high-resolution, high-vacuum microscope (SM-71480 JEOL, Massachusetts, USA). The microcapsules were attached to the sample holder with double-sided adhesive tape. SEM images were taken at room temperature and examined using an acceleration voltage of 15 kV according Navarro-Flores et al. (2020).

The microencapsulation efficiency of phenolic compounds (MYp) was calculated by using the total and superficial phenolic compounds in microcapsules, following the methodology described by Navarro-Flores et al. (2020). Briefly, to measure the total phenol content, 200 mg of the microcapsules were mixed with 2 mL of methanol:acetic acid:water solution (50:8:42 v/v/v). The mixture was shaken for 1 min, sonicated twice in a Cole-Palmer ultrasonic bath model 08855-00 (Cole-Palmer, Vernon Hills, IL, USA) at 25 °C for 20 min, and finally centrifuged at 4000 rpm for 5 min. The supernatant was used for quantifying the total phenolic content. For determination of superficial phenolic compounds content, 200 mg of the microcapsules were mixed with 2 mL of ethanol:methanol solution (1:1), agitated for 1 min, and then centrifuged at 4,000 rpm for 5 min, and the content of phenolic compounds was determined according to Navarro-Flores et al. (2020). The content of the total and superficial phenolic compounds was determined with Folin-Ciocalteu reagent, with the method described by Singleton et al. (1999) using gallic acid as the standard. The results were expressed as milligrams of gallic acid equivalents (GAE) per gram of powder. The efficiency of the microencapsulation of phenolic compounds was determined by Eq. 5:

M Y p % = P C t o t a l - P C s u p P C t o t a l × 100 (5)

where PCtotal is the total phenolic compound (mg GAE/g) and PCsup is the superficial phenolic compound (mg GAE/g).

The AA was determined by measuring the inhibitory effect against the DPPH radical, following the method described by Shekhar and Anju (2014), with some modifications. Briefly, several microcapsules´s solutions (25, 50, 100, 150, and 200 µg/mL) were prepared. Three milliliters of each solution were mixed with 1 mL of DPPH (0.1 mM). After 30 min of incubation, the absorbance of the solution was measured at 517 nm. The AA was calculated using equation 6:

A A % = A b s   c o n t r o l - A b s   s a m p l e A b s   c o n t r o l × 100 (6)

where Abs control is the absorbance of the control and Abs sample is the absorbance of the sample.

The EC₅₀ value of the sample, which represents concentration required to inhibit 50 % of the DPPH radical, was calculated using the inhibition curve.

Finally, microcapsules with the best properties, such as low solubility index, higher antioxidant activity, and greater encapsulation efficiency of phenolic compounds and probiotics, were selected for the next stage of this research. Once selected, the effect of applying these microcapsules to fresh pieces of jicama was studied.

To determine the effect of the addition of the edible coating on the physicochemical and microbiological properties of the minimally processed jicama roots, five types of coatings were evaluated: (1) gelatin-maltodextrin (1:25) 26 % (w/w) aqueous solution (referred as “C”); (2) GCE at a final concentration of 4.2 mg GAE/mL and Lactobacillus acidophilus and Bifidobacterium spp. at a final concentration of 10⁹ and 10⁸ CFU/mL, respectively, added to a gelatin-maltodextrin (1:25) at 26 % (w/w) aqueous solution (referred as “EP”); (3) GCE at a final concentration of 4.2 mg GAE/mL added to gelatin-maltodextrin (1:25) 26 % (w/w) aqueous solution (referred as “E”); (4) Lactobacillus acidophilus and Bifidobacterium spp. at a final concentration of 10⁹ and 10⁸ CFU/mL, respectively, added to gelatin-maltodextrin (1:25) 26 % (w/w) aqueous solution (referred as “P”), and (5) microcapsules obtained after double spray drying process (referred as “MC”).

The jicama roots were washed, disinfected, and cut into cubes (2 x 2 x 1 cm, 5±0.5 g) using a sterile knife. For coatings C, EP, E, and P, the jicama roots were immersed in the respective mixtures for one minute. For treatment MC, the jicama was coated with a thin layer of powder (approximately 0.3 grams of microcapsules per piece). Previous results indicated that this method produced a uniform layer of the microcapsules on the surface of each jicama piece. The samples coated were stored in polypropylene containers (4 x 6 x 6 cm) at 4 °C for six days. Microbiological and physicochemical properties (weight loss, pH, color, total phenolic compounds, caffeine and chlorogenic acid) of the samples were analyzed at 0, 1, 3, and 6 days.

To measure the weight loss, the jicama was weighed on the sampling days. The total weight loss was calculated by equation 7:

T o t a l   w e i g h t   l o s s   % = W e i g h t   ( t ) W e i g h t   o n   d a y   0 × 100 (7)

The surface color of the jicama was determined using a portable colorimeter (ColorTec, Clinton, NJ, USA). The values of L* (luminosity), a* (-green a + red), and b* (-blue a + yellow) were recorded, and the chromaticity (C*) was then calculated using equation 8:

C * = ( a * 2 + b * 2 ) 1 / 2 (8)

To measure the pH, the samples were blended, and the juices were centrifuged at 4500 rpm for 3 min at 4 °C before measuring pH using a pH meter (Hanna Instruments HI981031, Woonsocket, RI, USA).

The extracts used for TPC, CF and CL determinations were obtained according to the methodology described by Desai et al. (2019). For that, jicama samples were freeze-dried using a lyophilizer (Labconco FreeZone 4.5 L, Kansas City, USA) at - 40 °C and 0.250 mbar for 48 h. Then, 0.5 g of the lyophilized sample was mixed with 2.5 mL of a methanol:acetic acid:water solution (50:8:42 v/v/v). The mixture was shaken for 1 min, sonicated twice in a Cole-Palmer ultrasonic bath model 08855-00 (Cole-Palmer, Vernon Hills, IL, USA) at 25 °C for 20 min, and finally centrifuged at 4000 rpm for 5 min. The supernatant was used for quantifying the phenolic compound content according to Joya-Dávila et al. (2023).

Caffeine and chlorogenic acid were quantified by high-performance liquid chromatography (HPLC) with a Kromasil 100-5-C18 column (4.6 x 150 mm, 5 µm, 100 A- Supelco, Bellefonte, CA, USA), using a diode array detector (PerkinElmer Series 200 HPLC Systems, Shelton, CT, USA). The samples were filtered with a 0.22 µm millipore membrane. The mobile phase was acetonitrile/formic acid at 0.1 % (80:20, v:v) (Phase A) and formic acid at 1 % (v/v) (Phase B) at a 10:90 ratio with a constant flow of 1 mL per min in isocratic mode. Quantification was performed at 280 nm for CF and 320 nm for CL, and 10 µL of the sample were injected into the HPLC. In addition, standard solutions of the analytes to be quantified (50, 100, 200, 300, 400, 500, and 700 mg/L) were prepared for elution times and respective calibration curves. Metabolites were expressed in milligram GAE per gram of jicama root in dry basis.

A completely randomized experimental design with three replicates was employed for two evaluations. The results were analyzed using an analysis of variance (ANOVA) to determine significant differences between treatments (p ≤ 0.05). Honestly-significant-difference (HSD) or Tukey test were used for mean comparisons. Statistical analyses were carried out using Statgraphics Centurion XVI software.

The results indicated that the encapsulation efficiency of Lactobacillus acidophilus and Bifidobacterium spp. was not significantly affected by the inlet air temperature, regardless of whether single or double spray drying was used. After the single drying, cell viability ranged from 9.39 to 9.12 log CFU/g for Lactobacillus acidophilus and 7.91 to 7.85 log CFU/g for Bifidobacterium spp. The encapsulation efficiency of both microorganisms at 120 or 140 °C after the single drying was around 90 % (Table 1). However, the encapsulation efficiency for both microorganisms after the double drying process was around 73- 77 %. Despite this reduction, cell viability remained at 7.2 log CFU/g for Lactobacillus acidophilus and 6.2 log CFU/g for Bifidobacterium spp. Despite the decrease in cell viability, the use of chitosan as a coating material allowed obtaining powders with a probiotic content higher than 10⁶ CFU/g of microcapsules. Similar results were reported by Pupa et al. (2021) and Flores-Belmont et al. (2015), who encapsulated different species of lactic acid bacteria with chitosan through a double spray drying process, with encapsulation efficiencies of approximately 70 %.

Table 1

Spray drying	Inlet air temperature (°C)	Lactobacillus acidophilus (%)	Bifidobacterium spp. (%)
	120	92.13±1.28 a*	92.55±1.34 a
Single	140	92.28±1.49 a	91.31±2.83 a
	120	76.24±0.54 b	77.18±0.11 b
Double	140	73.30±1.07 b	73.48±2.23 b
HSD		4.68	7.81

* Means followed by different lowercase letters in a column are significantly different according to the Tukey HSD test (p ≤ 0.05). Medias seguidas con diferentes letras minúsculas en una columna son significativamente diferentes de acuerdo a la prueba de Tukey (p ≤ 0.05).

Micrographs show that the microcapsules had a spherical shape with dents and free of cracks on the surface, and an approximate average diameter of 15 µm (Figure 1). For microcapsules obtained by single and double spray drying at 120 and 140 °C, the size did not differ. The solubility of the microcapsules obtained by single spray drying ranged from 88 to 89 % (Table 2). These results are similar to those reported by Navarro-Flores et al. (2020), who encapsulated phenolic compounds using maltodextrin and other unconventional agents. These high solubility index could be attributed to the high solubility of the encapsulant agents (Fazaeli et al., 2012). Additionally, gelatin and maltodextrin contain hydrophilic sections, so they could interact and create a more soluble particle in aqueous environments (Semenova et al., 2002). Moreover, the water solubility index decreased for the microcapsules obtained by double microencapsulation through spray drying with chitosan (Table 2), compared with microcapsules obtained by single spray drying. This reduction can be attributed to the low solubility of chitosan at pH values above 6.5 (Aranaz et al., 2021). These results are similar to those reported by Flores-Belmont et al. (2015), who indicated that double microencapsulation with chitosan resulted in less insoluble powders in water (pH 7).

Figure 1

Table 2

Treatment	Water solubility index (%)	Water absorption rate (g/g)	Swelling capacity (g/g)	Phenolic compound (mg EAG/g)	Chlorogenic acid (mg/g)	Caffeine (mg/g)	Microencapsulation efficiency of phenolic compound (%)	IC50 (µg/mL)
Single 120 °C	88.53±1.47 a*	0.11±0.04 b	0.078±0.011 a	11.89±0.01 a	4.57±0.02 a	2.74±0.38 a	92.14±0.11 a	110.21±2.61 a
Single 140 °C	89.93±1.95 a	0.12±0.02 b	0.092±0.022 a	8.93±0.66 b	4.43±0.22 a	2.70±0.04 a	93.16±0.60 a	114.43±1.65 a
Double 120 °C	78.90±0.76 b	0.34±0.05 a	0.037±0.002 b	9.62±0.12 b	4.21±0.31 a	2.47±0.05 a	91.60±0.40 a	111.42±3.37 a
Double 140 °C	78.39±0.15 b	0.30±0.08 a	0.037±0.002 b	8.06±0.44 b	4.28±0.01 a	2.22±0.12 a	92.19±0.23 a	116.28±0.97 a
HSD	3.34	0.14	0.03	1.64	0.77	0.83	1.56	9.51

*Means followed by different lowercase letters in the same column are significantly different according to the Tukey HSD test (p ≤ 0.05). Medias seguidas con diferentes letras minúsculas en la misma columna son significativamente diferentes de acuerdo a la prueba de Tukey (p ≤ 0.05).

Water absorption rate values of microcapsules ranged from 0.11 to 0.34 g/g (Table 2). These values are similar to those reported by other authors (Da Costa et al., 2018; Navarro-Flores et al., 2020). It has been reported that variations in WAR may be due to the different degrees of participation of hydroxyl groups present in encapsulant agents in the formation of hydrogen bonds with water (Ahmed et al., 2010; Da Costa et al., 2018). The WAR of microcapsules obtained by single spray drying were lower than those by double spray drying with chitosan. This reduction can be attributed to the low solubility of chitosan at pH values above 6.5 as mentioned previously. At basic pH, the amino groups of chitosan are in their deprotonated form (-NH₂), which reduces their ability to interact with water and decreases the polymer´s solubility (Aranaz et al., 2021). SC values ranged from 0.037 to 0.092 g/g (Table 2). The SC values decreased significantly (p ≤ 0.05) for the microcapsules obtained by double spray drying compared with microcapsules obtained by single spray drying, probably due to the presence of chitosan. Ahmed et al. (2010) reported that a low swelling capacity is related to the greater stability of microcapsules, which reduces their ability to swell.

The inlet air temperature and the double encapsulation process with chitosan did not have a statistically significant effect (p ≥ 0.05) on the encapsulation efficiency of phenolic compounds, with percentages ranges of 91.60 - 93.16 % (Table 3). The total phenol content in microcapsules ranged from 8.06 to 11.89 mg GAE/g of powder (Table 3). These values are similar to those reported by Desai et al. (2019) for green coffee extract encapsulated with maltodextrin, with a TPC of 11.98 mg GAE/g of powder.

Table 3

Phenolic compounds (mg GAE/g of jicama roots in dry base)
Treatment	Time (days)				HSD
	0	1	3	6
C	0.99±0.01 cA*	0.99±0.01 cA	0.96±0.01 cA	0.99d±0.02 cA	0.06
EP	1.50±0.02 bA	1.50±0.04 bA	1.50±0.01 bA	1.49.44±0.01 bA	0.10
E	1.50±02 bA	1.50±0.03 bA	1.50±0.03 bA	1.49±0.01 bA	0.07
P	0.97±0.01 cA	0.98±0.01 cA	0.98±0.1 cA	0.98±0.01 cA	0.03
MC	4.31±0.12 aA	3.93±0.02 aAB	3.38±0.21 aBC	3.00±0.12 aC	0.57
HSD	0.22	0.09	0.40	0.22

C (Control), EP (green coffee extract/probiotics), E (green coffee extract), P (probiotics), MC (microcapsules with chitosan obtained by double spray drying). *Means followed by different lowercase letters in the same column are significantly different according to the Tukey HSD test (p ≤ 0.05). Means followed by different uppercase letters in the same row are significantly different according to the Tukey HSD test (p ≤ 0.05). C (Control), EP (extracto de café verde/probiótico), E (extracto de café verde), P (probióticos), M (microcápsulas con quitosano obtenidas mediante doble secado por aspersión). * Medias seguidas con diferentes letras minúsculas en la misma columna son significativamente diferentes de acuerdo a la prueba de Tukey (p ≤ 0.05). Medias seguidas con diferentes letras mayúsculas en la misma linea son significativamente diferentes de acuerdo a la prueba de Tukey (p≤ 0.05).

The results indicated that increasing the inlet air temperature to 140 °C or the double spray drying process, the total phenol concentration of the microcapsules decreased significantly (p ≤ 0.05). Despite the decrease in phenolic compounds, the antioxidant activity, measured as IC₅₀, remained unchanged. During spray drying, some phenolic compounds may degrade; however, new derivative compounds that are highly effective at inhibiting free radicals can be formed, as noted by Abrahão et al. (2019). Additionally, during thermal process, the Maillard reaction can occur, producing complexes with varying degrees of antioxidant activity (Liang et al., 2016).

The results also showed that around 110 - 116 µg/mL of microcapsules was needed to inhibit 50 % of DPPH radical (IC₅₀), and the double encapsulation process did not significantly affect this IC₅₀ value. In addition, neither the inlet air temperature and double encapsulation caused significant differences in the concentrations of chlorogenic acid and caffeine. This suggests that the double encapsulation process using chitosan effectively preserves both phenolic compounds and their antioxidant activity.

Based on these results, only the microcapsules obtained by double spray drying with chitosan at an inlet air temperature of 120 °C were used for the subsequent jicama coating experiments.

Weight loss results (Figure 2a) showed that jicama coated with microcapsules obtained by double encapsulation with chitosan (MC) showed the highest weight loss at the end of a 6 days of storage. Moreover, EP, E, and P treatments provided a significant additional protection (p ≥ 0.05) against weight loss compared to treatment MC. Wong et al. (2021) reported that weight loss in food during storage is mainly due to water migration from plant tissues to the outdoor environment through transpiration. In addition, the moisture difference between the jicama and the environment was probably the driving force for weight loss.

Figure 2

The pH of the jicama decreased significantly during storage (p ≤ 0.05), with the lowest pH values observed in treatments containing probiotic microorganisms (MC, EP and P) compared to the treatments without probiotics (Figure 2a). This could be attributed to the fact that during storage of jicama, even under refrigeration, probiotics could use the nutrients present in the coating and/or jicama pieces, producing organic acids, such as lactic acid, which could cause a decrease in pH. Wong et al. (2021) reported similar pH decreases in fresh-cut apple slices coated with Lactobacillus plantarum. The decrease in pH during the storage of minimally processed foods can be attributed to the activity of endogenous enzymes, which can produce acids and contribute to pH reduction. In treatments containing probiotics, the pH decrease can be attributed to the microbiological activity of the added microorganisms (Varoquaux and Wiley, 2017). Among the treatments with probiotics, the most pronounce pH reduction in jicama was observed in those with free microorganisms (treatments EP and P) (Figure 2a). This pH reduction could suggest a likely decrease in product acceptance. Otherwise, the pH of the jicama coated with the microcapsules (treatment MC) remained almost constant during storage. This could be attributed to the fact that spray drying decreased the cell metabolic activity of the bacterial cells (Behboudi-Jobbehdar et al., 2013).

Color is another important attribute of minimally processed foods, as affects the appearance and consumer’s acceptance of the product. On the cutting surface, cell rupture can occur, allowing substrates and oxidizers to come into contact. Therefore, one of the main objectives during the minimum processing of fruit and vegetables is to preserve the original color. Changes in the color of the samples were expressed through chromaticity (value C*) and luminosity (L^*) with respect to time (Figure 2c). In general, the results indicated that at the beginning of storage, the samples that had the coating with the unencapsulated green coffee extract (E and EP) were significantly opaquer than the control, whereas samples coated with powder obtained from double spray drying showed L* values similar to the control treatment. This behavior could be attributed to the color masking effect of the encapsulant agents on the color of the green coffee extract (Piedrahíta et al., 2018). After 6 days of storage, however, there was no significant statistical difference (p ≥ 0.05) in the luminosity of the samples. Color changes in the samples were expressed through chromaticity (C* value) over time; after 6 days of storage, there were no significant changes in the color of the samples.

The viability of Lactobacillus acidophilus and Bifidobacterium spp. in different types of coatings for minimally processed of jicama´s pieces during storage at 4 °C are shown in Figures 3 a and 3b, respectively. As can be seen, the number of Lactobacillus acidophilus and Bifidobacterium spp. cells remained constant during the 6 days of storage in EP and P treatments. This could have occurred because microorganisms remain metabolically active, probably by using impregnated carbohydrates and/or nutrients from the jicama as a carbon source (Wong et al., 2021). For the MC treatment (jicama coated with microcapsules) after 3 days of storage, the viability of microorganisms decreased significantly (p ≤ 0.05) (Figures 3a and 3b), probably because double spray drying with chitosan caused damage to the cell membrane of the probiotics. Therefore, when the microcapsules were applied to the jicama, they were hydrated, and the probiotics were reactivated. However, the microorganisms, having been damaged in the double drying, began their death phase.

Figure 3

The results of the total phenol content (mg/g of jicama roots in dry basis) during storage are presented in Table 3. The control treatment had a total phenol concentration of 0.99 mg GAE/g. Treatments E, EP, and MC exhibit higher total phenol content than the control (C). These results could be attributed to the green coffee extract present in these treatments, which were reported as an excellent source of phenolic compounds (Desai et al., 2019). The main phenolic compounds present in the green coffee extract are caffeine and chlorogenic acid, so these metabolites were quantified (Supplementary Fig. S1). Treatments C and P did not show detectable levels of caffeine or chlorogenic acid. In contrast, treatments E and EP resulted in caffeine and chlorogenic acid content to remain in the range of 0.43 - 0.38 mg/g and 0.42- 0.41 mg/g, respectively, throughout storage.

In the MC treatment, the content of caffeine (0.72 - 0.48 mg/g) and chlorogenic acid (1.11- 0.55 mg/g) were significantly higher (p ≤ 0.05) during the entire storage compared with the other treatments. During storage, the concentration of total phenols, caffeine, and chlorogenic acid decreased significantly (p ≤ 0.05) in the samples of the MC treatment (jicama coated with the microcapsules obtained by double spray drying), compared with the other treatments. It has been reported that incorporating probiotics into vegetables matrices using the immersion technique allows microorganisms to enter the interior of the food through capillarity, promoting their adherence and protecting them from external conditions (De Oliveira et al., 2017). Additionally, refrigeration helps maintain the stability of probiotics, as reported by Wong et al. (2021). However, the MC treatment presents a higher content of these phenolic compounds (caffeine and chlorogenic acid) throughout the complete jicama storage. The reduction of these compounds concentration could be originated for the microcapsule’s hydration and their partial hydration during the storage of the food, which causes the release of phenolic compounds into the outside environment. Franҫa et al. (2018) reported that in chitosan microcapsules the active compound is trapped in the nucleus and covered by a chitosan layer, which, depending on storage conditions, can swell and then release the nutrient.

Figure S1