Encapsulation efficiency and powders stability and retention of compounds . 108

Table 6 shows the encapsulation efficiency obtained for all particles produced, the contents of phenolic compounds and anthocyanins in powders during the period of 90 days of storage and the retention of compounds after 90 days. Encapsulation efficiency ranged between 52.3 and 67.5% for phenolic compounds and from 4.2 to 47.4% for anthocyanins. Regarding to the effect of wall material concentration on encapsulation efficiency, in general, the increase in yeast concentration led to a decrease in encapsulated compounds. Thus, highest phenolic compounds and anthocyanins encapsulation efficiencies were obtained for GP5 and J5. The higher concentration of yeasts in relation to the extract may increase the viscosity of the feed solution, contributing to cells aggregation and, consequently, less contact area and active sites available for compounds bounding and entrance.

Encapsulation efficiencies of phenolic compounds were higher in comparison to anthocyanins, for both extracts GPE and JE. The complex nature of the extracts used in this work, presenting several different compounds in their composition, may lead to a competition to bind into the cell wall. In addition, as anthocyanins were retained mainly in the cell wall, it is possible that their molecule size could have impaired their passage through yeast pores.

Malvidin-3-glucoside is the major anthocyanin in Bordeaux grapes (DE SOUZA et al., 2015) and delphinidin-3-glucoside and cyanidin-3-glucoside are found in jabuticaba peels (BARROS et al., 2019). The chain length of these mentioned anthocyanins is higher than the chain length of gallic and ellagic acids, phenolic acids commonly found in Bordeaux grape pomace and jabuticaba peels (INADA et al., 2020; ROCKENBACH et al., 2011), respectively. With extended chains, the number of -CH2- groups increases making

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the apolar area longer and more difficult passage through the polar part in the cell structure. This polar region of the cell membrane plays an important role in the diffusion and the more polar the molecule is, the better its diffusion. Therefore, the polarity of molecules is an important factor able to influence the passage of molecules through yeast membrane and, consequently, the encapsulation achievement (PHAM-HOANG;

VOILLEY; WACHÉ, 2016).

Table 6 - Phenolic compounds and anthocyanins stability in powders produced by encapsulation of extracts from grape pomace and jabuticaba byproducts in yeasts Saccharomyces cerevisiae, encapsulation efficiency (EE) and compound retention (CR) after

storage

Sample EE (%) Day 0 Day 15 Day 30 Day 60 Day 90 CR (%)

Phenolic compounds (mg EAG/g of particle)

GP5 67.5^A 154.4^Aa±1.4 113.0^Ab±2.8 113.8^Ab±3.5 111.9^Ab±2.1 114.0^Ab±1.7 73.8^C GP10 67.2^A 78.9^Ba±0.07 65.3^Bb±2.3 61.5^Bb±5.7 52.5^Bc±0.7 64.2^Bb±0.7 81.4^B GP15 64.7^B 58.9^Ca±0.8 51.0^Cc±0.7 46.6^Cd±0.8 53.5^Bbc±0.7 54.7^Cb±2.4 92.9^A J5 63.6^A 360.4^Aa±2.0 331.8^Ab±4.8 286.9^Ac±2.0 279.3^Ac±2.5 283.8^Ac±2.7 78.7^B J10 56.1^B 222.8^Ba±1.5 214.6^Ba±16.7 209.3^Ba±2.5 212.8^Ba±2.5 212.8^Ba±8.7 95.5^A J15 52.3^C 190.2^Ca±2.2 111.9^Cc±7.3 153.3^Cb±2.5 153.9^Cb±5.4 163.2^Cb±2.7 85.8^AB

Anthocyanins (mg/g of particle)

GP5 11.1^A 17.9^Aa±1.0 13.9^Ab±0.5 11.9^Abcd±2.1 10.7^Acd±0.6 9.9^Ad±0.8 55.3^B GP10 7.4^B 11.1^Ba±0.3 5.9^Bb±0.3 3.5^Bd±0.2 5.4^Bbc±0.2 5.0^Bc±0.08 45.0^C GP15 4.2^C 5.3^Ca±0.3 4.4^Cb±0.3 3.2^Bc±0.04 4.4^Bb±0.3 4.5^Bab±0.2 84.9^A J5 47.4^A 14.8^Aa±0.5 14.1^Aa±0.5 11.2^Ab±0.8 11.9^Ab±0.2 9.2^Ac±0.1 62.2^A J10 30.5^B 12.5^ABa±1.6 10.5^Bab±0.4 8.0^Bbc±0.2 7.3^Ac±1.7 7.0^Bc±0.4 56.0^A J15 18.3^C 10.2^Ba±0.8 7.9^Cb±0.2 6.7^Bb±0.7 6.8^Ab±1.5 6.1^Bb±0.1 59.8^A

Where GP5. GP10 and GP15 are the powders obtained by the encapsulation of extracts from grape pomace in Saccharomyces cerevisiae using 5, 10 and 15% of yeasts, respectively. J5, J10 and J15 are the powders obtained by the encapsulation of extracts from jabuticaba byproducts in Saccharomyces cerevisiae using 5, 10 and 15% of yeast, respectively. Capital letters in the same column and small letters in the same row indicate there is no significant

difference (p > 0.05) among samples, considering the same raw material.

Reference: Elaborated by the author

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In comparison to other works performed using yeast cells as carrier materials, Nguyen et al. (2018) encapsulated anthocyanins from Hibiscus (Hibiscus sabdariffa L.) in yeast cells and obtained an encapsulation efficiency of around 27%

under optimized conditions, using a concentration of 100 g L^-1 of dry yeast for anthocyanin-rich hydroalcoholic extract. Medeiros et al. (2018) obtained encapsulation efficiencies of 33.1 and 49.5% for the internalization of curcumin and fisetin into Saccharomyces cerevisiae cells, respectively. From these results, it can be inferred that polarity is a really crucial factor that may have influence on the compounds entrapment. Although yeasts have affinity for both hydro and lipophilic compounds, due to the presence of phospholipids polar heads toward outside and nonpolar heads oriented to the center of the membrane (WANG; CHEN, 2009), it seems that is easier to incorporate hydrophilic compounds because of the more polar surface. That explains higher encapsulation efficiencies for compounds such as fisetin and other phenolic compounds and lower for curcumin.

Related to compounds stability, there was in general a decline in the content for both phenolic compounds and anthocyanins between time 0 and 90 days, as expected. For all times there was a significant difference among the three treatments, where GP5 and J5 presented the highest content of phenolics at all points analyzed.

The retention of phenolics after 90 days of storage was higher with larger amounts of yeasts in the medium for samples prepared with grape pomace extract, with retentions of 73.8% for GP5 and 92.9% for GP15. This trend would allow to infer that the yeast in greater quantity in the sample would protect the phenolics, however, it was not so clear for the extract of jabuticaba, since the treatment with 10% had higher retention (95.5%) of phenolic compounds in comparison to GP5 and GP15.

For anthocyanins, GP10 also showed an irregular behavior, presenting lower retention. Anthocyanin retentions for J5, J10 and J15 were not significantly different.

4.3.2 Changes in powders color parameters after storage

The parameters of color obtained for powders produced by encapsulation of extracts from grape pomace and jabuticaba extracts in Saccharomyces cerevisiae are shown in Table 7.

Table 7 - Color parameters L*, a*, b*, hue angle (h*) and chroma (C*) for powders produced by encapsulation of extracts from grape pomace and jabuticaba byproducts in yeasts Saccharomyces cerevisiae

Sample Day 0 Day 90

L* a* b* h* C* L* a* b* h* C*

GP5 42.5^Ca±0.04 15.1^Aa±0.1 -4.1^Cb±0.04 -15.3^Cb±0.1 15.6^Aa±0.1 41.8^Bb±0.2 14.0^Ab±0.2 -2.8^Ca±0.1 -11.2^Ca±0.6 14,2^Ab±0.2 GP10 56.7^Ba±0.006 7.0^Bb±0.1 -0.5^Bb±0.06 -4.9^Bb±0.5 7.0^Bb±0.06 53.6^Ab±1.2 7.1^Ba±0.07 0.4^Ba±0.08 3.6^Ba±0.6 7,2^Ba±0.07 GP15 59.0^Aa±0.03 7.0^Ba±0.02 -0.2^Ab±0.05 -1.6^Ab±0.4 7.0^Ba±0.02 53.2^Ab±0.1 6.9^Cb±0.04 1.1^Aa±0.04 10.3^Aa±0.4 6,3^Bb±0.04 J5 31.0^Ca±0.08 25.3^Aa±0.06 4.9^Aa±0.08 11^Aa±0.2 25.8^Aa±0.05 31.0^Ca±0.9 22.8^Ab±0.4 4.4^Ab±0.1 10.9^Aa±0.08 23,3^Ab±0.4 J10 41.8^Ba±0.05 23.2^Ba±0.06 3.1^Bb±0.04 7.6^Bb±0.09 23.4^Ba±0.06 37.5^Bb±6.2 21.8^Bb±0.6 3.5^Ba±0.7 8.4^Ca±0.04 22,1^Ab±0.7 J15 50.5^Aa±0.01 19.0^Ca±0.02 2.5^Ca±0.02 7.4^Bb±0.06 19.2^Ca±0.02 48.4^Ab±0.9 17.3^Cb±0.1 2.8^Ca±0.08 9.1^Ba±0.2 17,5^Bb±0.1 Where GP5. GP10 and GP15 are the powders obtained by the encapsulation of extracts from grape pomace in Saccharomyces cerevisiae using 5, 10 and

15% of yeasts, respectively. J5, J10 and J15 are the powders obtained by the encapsulation of extracts from jabuticaba byproducts in Saccharomyces cerevisiae using 5, 10 and 15% of yeast, respectively. Capital letters represent the comparison between different treatments in the same time, while small

letters compare different times for the same treatment. Mean values followed by the same superscripts are not significantly different (p > 0.05).

Reference: Elaborated by the author

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For samples obtained by the encapsulation of GPE and JE, the luminosity was lower in the powders with the addition of 5% of yeast biomass. The lower addition of yeast and higher proportion of extract in the mixture may have led to the greater dispersion of pigments and, in consequence, the improved darker color. In addition, it is possible to notice an increase in the luminosity with the increase in the material wall content used. Chroma values were inversely proportional to L values and confirmed that GP5 and J5 powders present more intense colors.

The powders GP5 and J5 presented higher intensity of a* parameter indicating greater intensity of red color. For b* parameter, while the powder GP5 presented the lowest value, of - 4.1, J5 presented the highest value comparing with the other treatments, of 4.9. These values are related to the blue color, which can be explained by the presence of different anthocyanins in extracts. Hue angles around 0º all over the storage period indicated that a red color was established, typically found in anthocyanins extracts of red berries in non-basic media (TARONE et al., 2021).

After 90 days, GP10, GP15, J10 and J15 had significant losses of luminosity bringing a change in the color profile. GP5 had a slight darkening passed 90 days (decrease in lightness and chroma), probably because of compounds oxidation, however, this change was lower comparing with the other treatments with GPE. J5 did not present difference in the parameter L* after storage and this result may be interesting from the point of view of the application, since it is interesting to apply darker pigments that maintain their intensity all over the storage. In general, for all particles, there was a decrease in the parameter a* and an increase in b*, indicating the degradation of anthocyanins and phenolic compounds over time.