Evaluation of performance of maltodextrin and gum Arabic usage on volatiles profile of Spray-dried powders of sapota (Manilkara zapota) fruit

Abstract

This work has an objective to analyse and quantify the volatile compounds content in the dried powder of sapota using two encapsulating agents, maltodextrin or gum Arabic, and a mix of these agents. The major compounds found were ethyl acetate and 1-hexanol. Regarding the concentrations of these compounds present in the atomized samples, it can be verified that for both ethyl acetate and 1-hexanol their concentrations were higher in rehydrated gum Arabic dried powder (SG) sample, being 1237.15 µg/kg and 588.08 µg/kg, respectively, compared to the other two samples, rehydrated maltodextrin dried powder (SM) and rehydrated powder containing both encapsulating agents (SMG). The results of PCA analysis showed that the first two main components PC1 and PC2 were able to explain 80.90% of the total variation of the data, of which the main component PC1 explained 59.77% and the component PC2, 21.13%. %. From the heat map the top cluster includes the samples SM e SMG, while the bottom cluster contains the samples sapota juice and SG. Therefore, the sample SG presented greater similarity with the sample of fresh sapota juice as to the composition of volatile compounds.

Keywords:
sapota juice; spray drying; volatile compounds; gas chromatography-mass spectrometry

1 Introduction

The sapota (Manilkara zapota), a fruit belonging to the Sapotaceae family, despite being a fruit originating in Mexico, is the sixth most important fruit in India, found throughout the subcontinent of the country (Ghani, 2003; National Horticulture Board, 2021). Since it has a sweet and soft pulp with a granular texture, sapota is a very popular fruit (Siddiqui et al., 2014). Another important sensory characteristic of this fruit is the aroma, which is sweet and slightly astringent (Oliveira et al., 2011). In nutritional terms this fruit is a good source of dietary fiber, rich in calories providing about 83 cal per 100 g, in addition to being a source of a wide variety of vitamins A, C, niacin, folic acid and minerals such as iron, potassium and copper (Antala et al., 2021). In Brazil, sapota can be found in abundance in the northeast region of the country, where it is most consumed fresh. As it has a high water activity, the shelf life of sapota fruits decreases after ripening, thus favoring microbial growth, and hence its commercialization and production becomes very limited. Since the amount of water present in fruits is a large problem with regard to the preservation of this fruit, dehydration proves to be a very viable method for removing water, which consequently increases the shelf life of the fruit (Jangam et al., 2008).

There are some publications applying dehydration processes to sapota fruit and fruits belonging to the same family (Bala et al., 2017; Ganjyal et al., 2003; Jangam et al., 2008; Lasekan & Yap, 2018; Chong & Wong, 2015; Kumar et al., 2018). For the production of a dehydrated product, a spray dryer is widely used which is an economical process, since it is possible to transform liquid food directly into powder (Schweiggert et al., 2008; Ahmed et al., 2010; Ray et al., 2016; Shishir & Chen, 2017). One of the most important factors in this drying process is the carrier agent, used in conjunction with raw materials having high sugar content in fruits. There are several encapsulating agents, among them, maltodextrin is widely used, as it has advantages such as being colorless, high solubility, low hygroscopicity and low cost (Phisut, 2012; Rezende et al., 2018; Shishir & Chen, 2017). Another widely used encapsulating agent is gum Arabic, and its main characteristics are its solubility, low viscosity and emulsifying properties (Silva et al., 2013).

Fruits are rich in flavor and aroma and, the volatile compounds responsible for this, are produced by metabolic pathways during maturation, harvest, post-harvest and storage of fruits. Thus, the aroma and flavor arouse great interest from researchers in determining the volatile composition of foods, thus discovering which volatile compounds characterize a flavor and aroma (Ferreira et al., 2009). There are a few publications which reported volatiles compounds in sapota (Monteiro et al., 2018; Uekane et al., 2017; Lasekan & Yap, 2018).

Uekane et al. (2017) analyzed the volatile fraction of three fruits native to the Brazilian Amazon region: murici (Byrsonima crassifolia L., Malpighiaceae), bacuri (Platonia insignis M., Clusiaceae) e sapota (Manilkara sapota L.) and showed that most of the compounds identified were esters (33%), alcohols (27%), terpenoids (18%) and ketones (9%) and approximately 12% were aldehydes, carboxylic acids and hydrocarbons. The most abundant compounds found were acetic acid, palmitic acid, 3-methyl-3-buten-1-ol and geranylacetone. Lasekan & Yap (2018) characterized the aromatic compounds in fresh and dry sapota (Manikara zapota, L.) and showed that the overall aroma note of the fresh fruit was mainly caused by ethyl benzoate, (E)-2-hexenal, and β caryophyllene.

In reviewing all publications, it is possible to verify that research papers involving drying techniques, such as spray drying, using the sapota fruit, as well as the study of the volatiles in their dehydrated products are still limited, and hence there is a need for further studies of the volatiles responsible for the aroma of these dried products from the sapota. Thus, the present work aimed to analyze and quantify the volatile compounds present in the dehydrated powder of fruit obtained by spray-drying of sapota, using 2 different encapsulating agents (maltodextrin and gum Arabic), the performance of which was also compared. Moreover, Stir Bar Sorptive Extraction (SBSE) technique was applied for the first time in this work for capture of volatile compounds.

2 Materials and methods

2.1 Materials and reagents

The ethyl acetate standard was obtained from Sigma-Aldrich (St. Louis Missouri, United States), C8 - C40 n-alkanes standard were obtained from Sigma-Aldrich (St. Louis Missouri, United States). The encapsulating agent maltodextrin (DE 20) was purchased from Cargil Company, Brazil and the encapsulating agent Gum Arabic was purchased from Dinâmica Company, Brazil.

2.2 Sample preparation

The sapota (Manilkara zapota) fruits used in this work were purchased from the Central Market in the city of Aracaju, Sergipe, Brazil. The fruits were selected in ripened stage of its maturity and later taken to the Laboratory of Flavor and Chromatographic Analysis (LAF) of the Federal University of Sergipe (UFS), São Cristóvão, Brazil. The preparation of the sample was carried out following methodology described by Araujo et al. (2021). The fruits were washed in tap water, followed by separating the pulp from the peel and seed. The pulp was homogenized in a Waring blender (Deluxe 702 A, Brazil), and later sieved to remove the fibers and the juice stored at -18 °C.

2.3 Atomization process

The parameters for the atomization process of the sapota pulp were used in this study according to Araujo et al. (2021). For the drying process, the pulp was homogenized and filtered to obtain the juice that was used in the spray-drying process. The percentages of encapsulating agents used were based on the methodologies described by Chong & Wong (2015) (30%) and Araujo et al. (2021) (1:1), Fernandes et al. (2014) (1:1). The encapsulating materials were added to the juice in the following proportions: maltodextrin/juice (30:70 w/v); gum Arabic/juice (30:70 w/v); gum Arabic/maltodextrin/juice (15:15:70 w/w/v). The tests were carried out in a spray-dryer with spray nozzle system (LABMAQ Spray Dryer, Model MSDi 1.0). An injector nozzle with 1.2 mm diameter orifice was used, while airflow in the spray dryer was maintained at 4.00 m³/min and air pressure of 4 kgf/cm². The dryer was fed through a peristaltic pump, with a rotation speed of 0.44 L/h, inlet and outlet temperature of 140 °C and 65 °C, respectively. For all the analyses, the dried powder was rehydrated to reach the °Brix corresponding to the juice with addition of maltodextrin (35.81 °Brix), gum Arabic (34.88 °Brix) and the mixture of these two encapsulating agents (35.31 °Brix) before drying process. The dried samples were stored in amber colored glass bottles, duly protected from light and the bottles were stored in a desiccator.

2.4 Extraction of volatile compounds by Stir Bar Sorptive Extraction (SBSE)

The volatiles of sapota juice and rehydrated dried powders were extracted by SBSE following the methodology recommended by Leite et al. (2018). In a 20 mL vial were added 10 g of rehydrated dried powder, 3 g of NaCl and a 10 mm PDMS twister (Gerstel, Mülheim an der Ruhr, Germany), and it was continuously stirred for 30 min at room temperature. After this extraction the twister was removed from the sample, washed with distilled water and dried with soft paper. The extraction was carried out in triplicate for each sample.

2.5 Analysis of volatile compounds by GC-MS

The extracted compounds were desorbed on a Thermal Desorption Unit (TDU) (Gerstel) equipped with a cold injection system (CIS) (Gerstel, Mülheim an der Ruhr, Germany), which preserves and concentrates the volatile compounds of the samples. The TDU temperature was programmed from 35 °C to 210 °C (10 min) at a rate of 60 °C/min, whereby the analytes were desorbed for 4 min and concentrated in the CIS-4, programmed from -35 °C to 260 °C at 10 °C/s to transfer volatiles onto the analytical column. The TDU was operated in a splitless desorption mode; the CIS-4 operated in PTV solvent vent mode and other conditions were: purge flow to split vent of 30 mL/min, vent 60 mL/min and pressure 16.40 psi. Separation and identification of the compounds was performed on a gas chromatograph (Agilent Model 7890B) coupled to a mass spectrometer (Agilent Model 5977 A MSD). The GC was equipped with a DB-5 MS capillary column (30 m × 0.25 mm. × 0.25 μm, Agilent). Helium was used as the carrier gas at a flow rate of 1.0 mL/min. The initial oven temperature was 35 °C (maintained for 4 min), then temperature was raised at 5 °C/min up to 250 °C. Volatile compounds were tentatively or positively identified by comparing the mass spectra of the sample compounds with the NIST (National Institute of Standards & Technology) database and comparing the linear retention index (LRI) of the standards and compounds with those of literature articles and other online databases viz. Flavornet, Pherobase and PubChem.

2.6 Quantification of volatile compounds

Quantification of all identified compounds was based on a method described by Xiao et al. (2015) and Xin et al. (2022). A volume of 100 μL of the deuterated standard (D8 ethyl acetate; Sigma-Aldrich at a concentration of 10μg/mL) was added to the samples before the extraction procedure. A response factor equal to 1.00 was considered between the relative peak areas of each compound and the peak areas of the deuterated standard.

2.7 Chemometric analysis

Principal Components Analysis (PCA), Hierarchical Clustering Analysis (HCA) and Heat map visualization were performed by using XLSTAT software Trial Version 2020 (Addinsoft Inc., New York, USA). PCA reduces the extensive chromatographic data matrix based on Pearson's correlation coefficients (p≤0.05), representing efficiently in graphical form. HCA groups the data by similarities and dissimilarities, and it was performed according to Euclidean distance calculated based on the concentration of each volatile compound.

3 Results and discussion

After the drying process, the powders obtained viz. SG Rehydrated dried powder of sapota juice with gum Arabic); SM (Rehydrated dried powder of sapota juice with maltodextrin); SMG (Rehydrated dried powder of sapota juice with maltodextrin and gum Arabic) had a moisture content of 4.37, 4.18 and 3.16%, respectively and were then submitted to analysis of volatile compounds.

3.1 Analysis of volatile compounds

The volatile compounds found in the sapota juice and in the rehydrated powders belong to the chemical classes of alcohols (22.4% of the identified compounds), aldehydes (20.6%), esters (25.8%), ketones (10.3%), terpenes (17.2%) and lactones (1.7%). The alcohols was the main class which had a large number (58) of volatile compounds identified in the samples; 34 compounds were in sapota juice; 27 compounds in SG; 26 compounds in SM; 27 compounds in SMG. The identified compounds, their respective retention indices and mean concentrations present in each sample are shown in Table 1.

Table 1
Volatile compounds in fresh sapota juice and in various rehydrated dried powders.

	Compounds		LRIL	LRIE		Sapota Juice		Rehydrated dried powder							Odor descriptors
								SM		SG			SMG
						Concentration (µg/kg)		Concentration (µg/kg)
	Alcohols
1	2,3-butanediol		783	782		nd		95.54 ± 0.75		22.48 ± 0.96			nd		fruity, creamy, buttery
2	1,3-butanediol		784	785		nd		nd		nd			2.48 ± 0.38		-
3	1-hexanolb,c		819	827		7235.37 ± 0.76a		66.02 ± 0.80c		588.08 ± 1.20b			61.83 ± 1.36c		pungent, fruity, alcoholic, sweet
4	3-hexen-1-olb		799	828		nd		nd		42.94 ± 0.23b			44.33 ± 0.47a		green leafy
5	1-butanol, 2-ethyl-		794	834		37.81 ± 0.35		nd		nd			nd		alcoholic
6	1-heptanol		972	972		29.45 ± 0.15		nd		nd			nd		musty, leafy, herbal, green, sweet,
7	benzyl alcohola,c,d,e,f		1041	1041		256.17 ± 0.62a		96.29 ± 0.42c		160.36 ± 1.80b			78.85 ± 1.29d		floral, rose, phenolic, balsamic
8	1-octanolb,c		1076	1054		412.91 ± 0.45		nd		nd			nd		waxy, green, citrus, floral
9	1-nonanol		1075	1074		nd		nd		32.27 ± 0.68			nd		fresh, clean, floral, orange
10	phenylethyl alcohol		1119	1119		936.14 ± 1.63a		122.55 ± 0.86d		387.01 ± 0.71b			173.49 ± 0.16c		sweet, floral, fresh,
11	3-phenylpropanolf		1235	1232		564.25 ± 0.56a		252.55 ± 0.72b		213.97 ± 0.46 c			88.27 ± 0.62d		spicy, cinnamon, fruity, floral
12	4-methoxyphenethyl alcohol		1377	1374		nd		nd		43.80 ± 0.74			nd		-
13	2,5-bis(1,1-dimethylethyl)phenol		1519	1514		nd		nd		4.21 ± 0.22			nd		-
	Total					9472.1		632.95		1495.12			449.25
	Aldehydes
14	hexanalf		781	799		93.68 ± 0.16a		66.38 ± 0.23b		36.49 ± 0.43c			38.12 ± 0.10c		green, leafy, fruity, woody
15	(E)-2-hexenala,b		797	821		49.53 ± 1.23b		56.65 ± 0.07a		17.40 ± 0.29c			23.70 ± 0.93c		green leafy
16	heptanale		892	896		nd		6.13 ± 0.75c		26.11 ± 0.47a			13.11± 0.61b		fresh, aldehydic, fatty, green
17	(E,E)-2,4-hexadienalb,f		908	908		nd		25.16 ± 0.23a		21.43 ± 0.51b			8.93 ± 0.46c		green, fruity, citrus, waxy
18	(Z)-2-heptenal		956	958		nd		4.92 ± 0.12		nd			nd		green, fatty, oily
19	benzaldehyded,e,f		960	960		429.18 ± 0.85a		94.86 ± 1.36c		110.08 ± 0.66b			95.76 ± 1.14c		sweet, almond, cherry
20	(E,E)-2,4-heptadienal		999	997		19.04 ± 0.75		nd		nd			nd		fatty, green, oily, aldehydic
21	Octanal		1005	1005		nd		3.90 ± 0.66c		20.46 ± 0.36a			6.30 ± 0.72b		waxy, citrus, orange peel,
22	benzeneacetaldehyde		1048	1047		nd		25.98 ± 1.44		nd			33.63 ± 0.93		green, sweet, floral, honey
23	Nonanal		1108	1107		nd		35.41 ± 0.42a		23.04 ± 0.56c			31.21 ± 0.62b		waxy, rose, orange peel
24	decanale		1205	1205		15.03 ± 1.29a		14.25 ± 0.82a		12.16 ± 1.02a			15.05 ± 2.03a		sweet, waxy, orange peel
25	Undecanal		1276	1300		nd		12.20 ± 0.17		nd			nd		waxy, soapy, floral, citrus,
	Total					606.46		345.84		267.17			262.81
	Terpenoids
26	Myrcenol		1076	1056		nd		27.40 ± 0.54		nd			nd		fresh, citrus, floral, clean
27	Linalool oxide		1078	1074		nd		nd		16.83 ± 0.45			nd		floral, herbal, earthy, green
28	Camphor		1152	1151		15.45 ± 0.94a		5.92 ± 0.54c		nd			7.35 ± 0.73b		camphor, minty, herbal, woody
29	Isoborneol		1174	1172		285.92 ± 1.25a		34.49 ± 0.92b		30.02 ± 0.88a			26.92 ± 0.31b		camphoreous, herbal
30	Levomenthol		1180	1172		nd		12.37 ± 0.46		nd			nd		peppermint, mentholic, minty
		Compounds	LRIL		LRIE		Sapota Juice	Rehydrated dried powder						Odor descriptors
								SM	SG		SMG
							Concentration (µg/kg)	Concentration (µg/kg)
31		Terpinen-4-olc,f	1185		1184		nd	nd	nd		12.73 ± 0.69			pepper, woody, earth, musty, sweet
32		Eugenolc,f	1367		1367		72.90 ± 0.36a	nd	nd		7.23 ± 0.57b			sweet, spicy, woody
33		Farnesane	1382		1379		nd	nd	nd		16.11 ± 0.91			-
34		Isoeugenol	1367		1396		nd	nd	5.71 ± 0.47		nd			sweet, spicy, floral
35		Methyleugenol	1412		1411		17.87 ± 0.25b	nd	nd		24.75 ± 0.58a			sweet, fresh, spicy, cinnamon
		Total					392.14	80.18	52.56		95.09
		Esters
36		Ethyl acetatea,e,f	584		584		6059.78 ± 2.34a	59.97 ± 6.52c	1237.15 ± 1.54b			86.94 ± 0.98c		fruity, sweet, grape
37		Butyl acetate	786		789		298.13 ± 0.87a	nd	7.62 ± 0.24b			nd		fruity, banana
38		Ethyl butanoateb	782		799		329.16 ± 0.34a	nd	12.87 ± 0.57b			nd		fruity, juicy fruit, pineapple
39		Ethyl 2-methyl-butanoate	794		830		22.92 ± 1.20	nd	nd			nd		sweet, green, apple, fruity
40		3-methyl-1-butyl acetate	839		853		3983.44 ± 0.75a	41.96 ± 0.55b	687.89 ± 0.41b			nd		banana, sweet, fruity
41		3-methyl-3-butenyl acetate	848		861		22.24 ± 0.85	nd	nd			nd		fruity
42		Heptyl pentanoate	865		899		33.91 ± 0.74	nd	nd			nd		fruity, apple, green apple
43		Methyl hexanoate	924		924		35.25 ± 0.45	nd	nd			nd		fruity, pineapple
44		Ethyl hexanoate	1002		1002		88.90 ± 0.78	nd	nd			nd		sweet, fruity, pineapple, green
45		Hexyl acetate	1017		1017		319.76 ± 1.35	nd	nd			nd		fruity, apple,sweet
46		Methyl benzoated,e,f	1100		1084		105.13 ± 0.41	nd	nd			nd		phenolic, almond, floral
47		Benzyl acetate	1171		1169		60.83 ± 0.21	nd	nd			nd		sweet, floral, fruity
48		Ethyl benzoatec,d,e,f	1178		1177		206.79 ± 0.14	nd	nd			nd		fruity, sweet
49		Diethyl butanedioate	1186		1188		53.82 ± 0.87a	nd	10.63 ± 0.25b			nd		fruity, apple
50		Ethyl benzenepropanoateb	1358		1353		36.52 ± 0.58	nd	nd			nd		spicy
		Total					11656.58	101.93	1956.16			86.94
		Ketones
51		2-heptanonef	870		870		nd	nd	11.81 ± 0.26			nd		fruity, spicy, sweet, herbal, coconut
52		6-methyl-5-hepten-2-oneb,c	989		988		42.04 ± 0.28a	4.70 ± 0.98c	nd			5.46 ± 0.76b		citrus green, lemongrass, apple
53		(E,E)-3,5-octadien-2-one	1075		1068		nd	nd	nd			81.86 ± 0.86		fruity, green, grassy
54		acetophenonec	1071		1071		202.17 ± 0.28a	27.29 ± 0.25b	14.16 ± 0.47c			11.08 ± 0.73d		sweet, pungent, almond, acacia
55		3,5-octadien-2-one	1098		1096		nd	nd	nd			26.60 ± 0.96		fruity, fatty, mushroom
56		benzophenone	1642		1644		nd	2.67 ± 0.34	nd			nd		balsam, rose, geranium
		Lactones
57		butyrolactone	919		917		nd	14.63 ± 0.76	nd			nd		creamy, oily, fatty, caramel
		Total						14.63
		Others
58		2,6,10-trimethyl-tetradecane	1552		1555		nd	nd	nd			4.03 ± 0.79		-
		Total										4.03

• LRI_L: Linear Retention Index from literature (National Institute of Standards & Technology, 2009); LRI_E: Linear Retention Index on HP5-MS obtained experimentally.
• ^a
  Laohakunjit et al. (2007); ^bMonteiro et al. (2018); ^cUekane et al. (2017);^d MacLeod & Troconis (1983);^eLasekan & Yap (2018);^f Pino et al. (2003).
• Concentrations expressed as Mean ± SD (n=3); SM: Rehydrated dried powder of Sapota juice with maltodextrin; SG: Rehydrated dried powder of Sapota juice with gum arabic; SMG: Rehydrated dried powder of Sapota juice with maltodextrin and gum Arabic. The mean values followed by the superscript letters in rows do not differ statistically from each other. The Tukey test was applied at a 5% probability level. nd = not detected.

In this work the presence of volatile compounds in sapota juice and in rehydrated powders obtained through the atomization process was studied. What was observed is that most of the aroma compounds identified in sapota juice were also found in samples of rehydrated powders, but only 14 compounds were identified in sapota juice, and some of these were lost during the drying process, as can be seen in Table 1.

Regarding the total concentration of each chemical class of volatile compounds (Table 1), it is possible to note that for the class of alcohols, aldehydes, esters and ketones, there was a reduction in concentration if we compare the sapota juice sample with that of rehydrated powders (SM, SG, SMG). This reduction can be explained, because during the atomization process, due to the hot air flow that is used in the process, a small quantity of solids is retained in the drying chamber (Forero et al., 2015). Each encapsulating agent behaved differently in relation to the preservation of the total concentration by classes of compounds. For the class of alcohols and ethers, for example, the concentrations that was before in the sapota juice sample, were 9472.1 µg/kg of pulp for alcohols and 11656.58 µg/kg of pulp for esters while after the drying process, the sample of rehydrated powder containing gum Arabic (SG) had a concentration of 1495.12 µg/kg of pulp for alcohols and 1956.16 µg/kg of pulp for esters. However, this didn't happen with other samples containing maltodextrin (SM) and a mixture of the two encapsulating agents (SMG) thus showing the efficiency of gum Arabic as an encapsulating agent in retaining the volatile compounds.

The initial total concentrations in the sapota juice for the aldehydes and terpenes were 606.46 µg/kg of pulp and 392.14 µg/kg of pulp, respectively (Table 1). The sample of rehydrated powder containing maltodextrin (SM) showed a greater efficiency in retention of volatile compounds, when compared with other samples, obtaining the total concentrations of 345.84 µg/kg of pulp for the aldehyde class and 80.18 µg/kg of pulp for the terpenes. For the ketone class, the rehydrated powder sample containing a mixture of the two encapsulating agents (SMG) stood out from other samples with a major decrease in these compounds, the values being 125.00 µg/kg of pulp while its content was 244.21 µg/kg of pulp in the sapota juice sample. In this work, only one compound belonging to the lactone class, butyrolactone was identified, which was only found in the SM sample but it was in very low concentration (14.63 µg/kg of pulp).

Although samples containing encapsulating agents have proved to be efficient in relation to the retention of the total concentration of various chemical classes, it is possible to observe (Table 1) that in relation to aroma compounds belonging to the esters class, that many of the compounds present in the sapota juice sample were not identified in the samples of rehydrated dried powders, although some compounds such as ethyl acetate, ethyl butanoate, butyl acetate, diethyl butanedioate and 3-methyl-1-butyl acetate also were present in the rehydrated powders samples.

Among the identified compounds, some were identified in all samples; these being 1-hexanol, benzyl alcohol, phenylethyl alcohol, isoborneol, 3-phenylpropanol, hexanal, (e)-2-hexenal, benzaldehyde, decanal, ethyl acetate, acetophenone (Table 1). However, there was a significant difference (p ≤ 0.05) between the samples of sapota juice and rehydrated dried powders (SM, SG and SMG). For the compounds 1-hexanol, benzyl alcohol, phenylethyl alcohol, benzaldehyde and ethyl acetate, its highest concentrations were found in the sample of rehydrated powder containing gum Arabic (SG) and their concentrations were 588.08, 160.36, 387.01, 110.08 and 1237.15 µg/kg of pulp, respectively. It is worth mentioning that the compounds 1-hexanol (sweet and fruity aroma) and ethyl acetate (sweet and fruity aroma), were in highest concentrations in the sapota juice samples, the values being 7235.37, and 6059.78 µg/kg of pulp, respectively. Moreover, after the drying process, these aroma compounds were well retained in juice containing gum Arabic. Another compound that showed a high concentration was 3-methyl-1-butyl acetate (banana odor, sweet and fruity aroma), which was in a concentration of 3983.44 µg/kg of pulp in sapota juice sample remained in a significant concentration (687.89 µg/kg of pulp) in the SG sample, but it was not found in the SMG sample.

Regarding the compounds 3-phenylpropanol, hexanal, (E)-2-hexenal, acetophenone and isoborneol the highest concentrations were obtained in the sample of rehydrated powder containing maltodextrin (SM), the values being 252.55, 66.38, 56.65, 27.29 and 34.49 µg/kg of pulp, respectively. As for decanal, its highest concentration (15.05 µg/kg of pulp) among the dried samples was in the sample of rehydrated powder containing a mixture of the two encapsulating agents (SMG).

There are already some publications (Uekane et al., 2017; Monteiro et al., 2018; Lasekan & Yap, 2018; MacLeod & Troconis, 1983; Pino et al., 2003; Laohakunjit et al., 2007) which studied the aroma compounds present in the sapota pulp, dehydrated fruit and fruits of the same family. Among the volatile compounds identified in these publications, those with the highest concentrations were 1-hexanol (7235.37 µg/kg of pulp), 3-methyl-1-butyl acetate (3983.44 µg/kg of pulp) and ethyl acetate (6059.78 µg/kg of pulp) (Table 1), were observed in the sapota juice sample.

The other sapota aroma volatiles are mostly benzyl-derivatives, in addition to alkyl benzoates and methyl salicylate, according to the literature (Uekane et al., 2017). Pino et al. (2003) also analyzed volatile compounds on sapota through an SDE extract and they obtained 34 compounds, ten of these were also found in this work. They reported the concentration of ethyl acetate being 1300 µg/kg of pulp, this value is much lower than found in this work in sapota juice sample (6059.78 µg/kg of pulp), while the value in the SG sample was very close (1237.15 µg/kg of pulp).

One factor that may explain the variation in the concentration of volatile compounds found in the present work is the extraction technique used in comparison with those reported in the literature The SBSE technique has been widely used and efficient for the extraction of volatile compounds in different matrices, and has advantages such as not using organic solvents, requiring a small amount of sample, having a low detection limit (LoD) and high extraction capacity of volatile and semi-volatile compounds compared to other extraction techniques (Starowicz, 2021; Franc et al., 2009). High et al. (2019) investigated the sensitivity, selectivity and reproducibility of the SAFE, SPME, SBSE and HSSE techniques for the analysis of volatile compounds from spray-dried New Zealand sheep milk and concluded that of the applied extraction techniques, SBSE demonstrated the best potential for extracting volatile compounds from this matrix. The SBSE technique detected 45 volatile compounds, while the SPME technique detected only 20 compounds. Regarding sensitivity, the SPME and HSSE methods were the least sensitive, detecting only a concentration of 173 µg/kg and 271 µg/kg respectively, while the SBSE extraction method detected a concentration of volatile compounds of 657 µg/kg. Bicchi et al. (2002) evaluated the efficiency of HSSE, SBSE and SPME extraction techniques on volatile compounds from roasted Arabica coffee and coffee brew and observed that the HSSE and SBSE techniques had a greater concentration capacity of volatile compounds than the SPME technique

On comparing the data obtained in this work, it can be concluded that these was a decrease in concentrations of most of the compounds present in the sapota juice sample in their dried samples (Table 1). Furthermore, there was not much difference in the amount of compounds identified in the dried samples; however for most of the compounds, the sample of rehydrated powder containing gum Arabic (SG) presented more relevant concentrations, than the others containing only maltodextrin (SM) or a mixture of encapsulating agents (SMG). The significant presence of these compounds quantified in dried sapota powder can be attributed to the efficiency of gum Arabic as an encapsulating agent, as well as to the spray-drying process (Forero et al., 2015).

3.2 Chemometric analysis

Chemometric analysis, Principal Components Analysis (PCA), Hierarchical Clustering Analysis (HCA), and heat map visualization were used to verify the effect of the atomization process with different encapsulating agents such as gum Arabic and maltodextrin, on the profile of volatile compounds in sapota juice.

The results of PCA of the data generated for sapota juice samples and their rehydrated powders are shown in Figure 1, which shows the variability in relation to the concentrations of volatile compounds. The score (Figure 1a) and loading (Figure 1b) plots obtained showed that the first two main components PC1 and PC2 were able to explain 80.90% of the total variation of the data, of which the main component PC1 explained 59.77% and the other component PC2, 21.13%.

Figure 1
Principal Components Analysis of concentrations of volatile compounds from sapota juice and their rehydrated dried powders. (a) Score plot; (b) Loading plot, volatile compounds are represented by same numbers as presented in Table 1.

The score plot (Figure 1a) shows the distribution of all studied samples in the first two main components while the loadings graph (Figure 1b) shows the distribution of the studied variables, that is, the volatile compounds, in the two main components. The sapota juice sample was allocated to PC1 positive axis. In contrast, the samples of the rehydrated powders were grouped in PC1 negative axis. The sample of rehydrated powder containing gum Arabic (SG) was allocated in a positive axis PC2, and the samples of rehydrated powders containing maltodextrin (SM), and gum Arabic and maltodextrin (SMG) were allocated to PC2 negative axis. All esters (compound numbers 36 to 50), 1-hexanol (3), 2-ethyl-1-butanol (5), 1-heptanol (6), benzyl alcohol (7), 1-octanol (8), phenylethyl alcohol (10), 3-phenylpropanol (11), benzaldehyde (19), (E,E)-2,4-heptadienal (20), isoborneol (29), and eugenol (32) were on the positive axes of PC1 and PC2. Furthermore, hexanal (14), (E)-2-hexenal (15), decanal (24), camphor (28), methyleugenol (35), 6-methyl-5-hepten-2-one (52), and acetophenone (54) were on the positive axis of PC1 and on the negative axis of PC2. These volatile compounds were correlated with sapota juice.

3-hexen-1-ol (4), 1-nonanol (9), 4-methoxyphenethyl alcohol (12), 2,5-bis(1,1-dimethylethyl) phenol (13), heptanal (16), octanal (21), linalool oxide (27), isoeugenol (34), and 2-heptanone (51) were on the negative axis of PC1 and on the positive axis of PC2. These volatile compounds were correlated with the sample SG. 2,3-butanediol (1), 1,3-butanediol (2), (E,E)-2,4-hexadienal (17), (Z)-2-heptenal (18), benzeneacetaldehyde (22), nonanal (23), undecanal (25), myrcenol (26), levomenthol (30), terpinen-4-ol (31), farnesane (33), (E,E)-3,5-octadien-2-one (53), 3,5-octadien-2-one (55), benzophenone (56), butyrolactone (57), and 2,6,10-trimethyl-tetradecane (58) were on the negative axes of PC1 and PC2. These volatiles were associated with the samples SM and SMG. These results corroborated with the data presented in Table 1, demonstrating that the atomization changes the volatile profile of sapota juice by the loss or generation of volatile compounds during the process.

However, the changes in volatile compounds of rehydrated sapota dried powders were different for the studied encapsulating materials. From the heat map (Figure 2), all samples were grouped into two clusters according to the amount of each compound. The top cluster includes the samples SM e SMG, while the bottom cluster contains the samples sapota juice and SG.

Figure 2
Hierarchical clustering analysis and heat map visualization generated data matrix of concentrations of volatile compounds of sapota juice and theirs rehydrated dried powders. The color scale represents the concentration of each volatile compound, ranging from red to yellow, which represents high and low concentration, respectively. Volatile compounds are represented by same numbers as presented in Table 1.

Thus, the sample of rehydrated powder containing gum Arabic (SG) presented greater similarity with the sample of sapota juice in relation to the composition of volatile compounds. In both samples, esters and alcohols presented higher concentrations in relation to the other volatile classes in the same sample, highlighting ethyl acetate (36), 3-methyl-1-butyl acetate (40), and 1-hexanol (3).

4 Conclusion

This work aimed to study the influence of the encapsulating agents of maltodextrin and gum Arabic on volatile compounds of sapota (Manilkara zapota) powder obtained by spray-drying. The major compounds with higher concentrations were ethyl acetate and 1-hexanol. Regarding the concentrations of these compounds present in the dried samples, it was verified that ethyl acetate and 1-hexanol concentrations were higher in sample SG compared to the other two samples, SM and SMG. From the heat map, the sample of rehydrated dried powder containing gum Arabic (SG) presented greater similarity with the sample of sapota juice in relation to the composition of volatile compounds. In both samples, esters and alcohols was the classes that presented higher concentrations in relation to the other volatile classes in the same sample, highlighting ethyl acetate, 3-methyl-1-butyl acetate, and 1-hexanol. In view of the results obtained, it can be concluded that the sample of rehydrated dried powder of sapota juice formulated with the use of gum Arabic (SG) showed higher concentrations in relation to most of the volatile compounds, as well as retained more volatile compounds present in sapota juice. Thus, it can be concluded that for sapota juice, the spay-drying process was more efficient when gum Arabic was used as the encapsulating agent which led to obtaining high quality product.

• Practical Application: This research work establishes development of the dehydrated powder of Sapota juice and to study the effect of drying process on volatile compounds using maltodextrin and gum Arabic encapsulating agents. The volatiles capture was performed using the Stir Bar Sorptive Extraction (SBSE) technique and no work has been performed using this technique earlier. It contributes significantly to the generation of new data in relation to the development and characterization of spray dried powders obtained from Sapota. This work is highly relevant not only from volatile compounds but also in its potential for commercial applications of dehydrated powder of Sapota.

• Funding

  This study was funded in part by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) vide research Project Instituto Nacional de Ciência e Tecnologia de Frutos Tropicais (Process 465335/2014-4). Authors gratefully acknowledge the financial support of Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil under Programa Nacional de Pós-doutorado (PNPD/CAPES - 086/2013 - Financial code 001) and to Fundação de Apoio à Pesquisa e a Inovação Tecnológica do Estado de Sergipe (FAPITEC) for their fellowships.

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Publication Dates

• Publication in this collection
  03 Apr 2023
• Date of issue
  2023

History

• Received
  21 Oct 2022
• Accepted
  12 Jan 2023