Introduction

Myrtus communis L., (also konown as “myrtle”) belongs to the family Myrtaceae. Unless otherwise indicated, the term “myrtle” throughout this study is used for Myrtus communis L. The fruits of myrtle are mainly black and white types. White fruits are generally consumed fresh, while black ones are consumed both fresh and dried. The fruits have been reported to have a high content of vitamins, phenolic compounds, antioxidants, tannins, fiber and also used as an important food ingredients given their rich content of calcium, magnesium, potassium and phosphorus [1]. The plant leaves contain many biologically active substances with medical, pharmacological and industrial importance [2]. These substances were shown to have bioactivities for alleviating or eliciting various health problems such as constipation, hemorrhoids, gum infections, diabetes, urinary tract, chest diseases, and wound healing [3,4,5,6].

Vitamins are an organic molecule that have diverse biochemical functions and an organism needs in small quantities for the proper functioning of its metabolism. Vitamins are classified as fat- and water-soluble and cannot be synthesized in the organism, therefore must be obtained through diet. Both deficiencies and excess of vitamins can potentially cause clinically significant illness [7].

Glutathione, a tripeptide with a gamma peptide linkage between the carboxyl group of the glutamate side chain and cysteine, is an important antioxidant for almost all life forms. It scavenges reactive oxygen species preventing cells against oxidative damage. The major oxidized form of glutathione is GSSG which is an indicator of oxidative stress. The pool of cellular GSH and GSSG is normally finely tuned [8].

Phenolics are found as secondary metabolites in plants, consisting various compounds such as complex flavonoids, simple flavonoids, phenolic acids and anthocyanins [9]. Phenolic compounds and their largest group flavonoids are highly potent antioxidants given their aromatic rings bearing hydroxyl groups. They cause the colorization of fruits and vegetables and some phenolic compounds play important roles in the activity of some enzymes [10].

Major and trace elements are extremely important for all living organism. Major elements like calcium, zinc, and iron are found in many tissues, including the structure of bones. Trace elements are important for living organism and act as cofactors in the structure of many enzymes. Deficiencies of trace elements have been reported to be cause of many diseases [11].

Being seasonal, the fruits of myrtle are preserved with different methods for year round consumer consumption [3]. Thus, the type of preservation or processing is important in terms of preserving the nutritional value and biochemical properties of the fruits. The fruits are mainly preserved by sun-drying, drying tunnels, vacuum-drying, microwave or heating ovens, and freezing [12]. Temperature, time, light intensity and humidity are the main factors contributing to variances in the nutrient content of preserved fruits [13].

The study is based on a comparative investigation of the vitamins (A, B, C, E), carotenoids (β-carotene and lycopene), functional peptides (glutathione, ghrelin), oxidative stress markers (GSSG and MDA), total phenolic and flavonoid substances and antioxidant capacity (DPPH, TEAC), the amount of Se, Cu, Fe, Mn and Zn elements in wild and cultivated myrtle fruits. In addition, effect of commonly used conservation methods on the studied parameters such as sun or microwave drying and freezing on these parameters studied as well.

Materials and methods

Materials

Mature myrtle fruits were harvested in December 2018 from Osmaniye, Turkey (Latitude: 37° 04′ 27.01" N, Longitude: 36° 14′ 52.01" E). They were identified as such by the Department of Botany at Firat University (Turkey). Fresh myrtle fruits were analyzed within 10 days of collecting; while frozen, sun and microwave-dried samples were analyzed within 10 days after drying. Frozen samples were kept at −20 °C until analysis. The samples were homogenized in a blender and used for the biochemical analyzes. Fresh and dried samples were kept in the refrigerator until analysis was completed [14]. Equipment and chemicals used by Bakar et al. [15], were also used in this study.

Microwave and sun drying

The fresh fruit samples were dried either in microwave or under the sun. In microwave (Vestel brand microwave (M.D-60 × 30, with 800-W power), they were exposed to drying 6 times for 5 min at full power (800 watts), while in sun-drying they were kept in a well-ventilated indoor area under sunlight for 5 days until 60% weight loss of the total weight in both cases.

Determination of vitamins A and E, β-carotene and lycopene

Homogenized fruit samples (1.00 g each) were transferred to a glass tube and 5.0 mL C2H5OH was added and the sample was sonicated for 10 min. The suspension was vortexed and then centrifuged for 3 min at 4500 rpm. Then 0.5 mL n-hexane was added to the supernatant, briefly vortexed and then centrifuged for 3 min at 4500 rpm. Hexane phase was pipetted into a glass tube and this process was repeated twice. The collected hexane phases were dried under nitrogen atmosphere and stored in a vacuum oven at 23 °C. The dry residue was dissolved in 1.0 mL CH3OH and transferred to HPLC vials and analyzed using a Supelcosil LC-18 column (25.0 cm × 4.6 mm × 5.0 μm) utilizing a mobile phase of CH3OH: ACN: H2O (63:33:4.0 v/v) with the flow rate of 1.0 mL/minute [16, 17].

Determination of vitamin C, ghrelin, glutathione and MDA

To the 2 g homogenized fruit sample 1.0 mL 0.5 M HClO4 was added and briefly vortexed. The total volume of each sample was completed to 6.0 mL with distilled water, sonicated for 10 min and centrifuged at 6000 rpm for 5 min. The supernatant was filtered (Whatman No. 1) and 1.0 mL filtrate was pippeted into HPLC vials. Vitamin C, ghrelin, glutathione and, MDA levels were determined using HPLC (Exsil column 100-5 ODS 25 cm, 4.6 mm ID, 5 μm) according to the methods by Ibrahim, Ibrahim, Mukhtar and Karatas, [17], Aydin et al. [18], Karatas et al. [19], respectively.

Determination of B vitamins

The filtrate obtained in Sect. 2.4 was also used for the analysis of B series of vitamins, utilizing a Supelcosil LC-18-DB column (150 mm × 4.6 mm ID, 5 µm). The sodium salt of 5 mM heptane sulfonic acid: 0.1% triethylamine at 25:75 (v/v) and pH adjusted 2.8 by orthophosphoric acid was used as mobile phase with the flow rate of 1.0 mL/minute [16, 20].

Extraction

The myrtle fruits (fresh, frozen and dried), subjected to different preservation treatments, were homogenized with a blender and sample (15.0 g) was taken into the cartridge and extracted with 300 mL CH3OH in Soxhlet apparatus for 4 h. The solvent was removed under vacuum by a rotary evaporator at 40 °C. The weighed dry extract was dissolved in 50 mL CH3OH and the solution was stored in the fridge at 4 °C until analysis [21].

Determination of total phenolic content

Total phenolic substance was determined spectrophotometrically using the Folin-Ciocalteu as described by Dewanto, Wu, Adom, and Liu [22]. A solution of 0.25 mL methanol extract, 0.50 mL distilled water, and 0.125 mL Folin-Ciocalteu reagent were mixed thoroughly and let stand at room temperature for 6 min. Then, 1.25 mL 7% Na2CO3 solution was added and the final volume was completed to 3.0 mL with distilled water. After 90 min at room temperature the absorption spectrum of samples was measured at 760 nm with a UV–visible spectrophotometer. The same protocol was followed for the gallic acid calibration curve for the estimation of gallic acid equivalent. The total phenolic content was determined from the obtained calibration curve and results are given as as µg GAE/g dw.

Determination of total flavonoids

The total flavonoid content was determined spectrophotometrically as described by Dewanto, Wu, Adom, and Liu [22]. A mixture of 25 µL sample, 1.25 mL distilled water, 75 µL 5% NaNO2 and 150 µL 10% AlCl3 solution was prepared in a glass tube and allowed to stand at room temperature for 5 min. Then 0.50 mL 1.0 M NaOH solution was added and total volume was completed to 2.50 mL with distilled water and the absorbance was recorded at 400 nm. The same procedures were followed for the quercetin calibration curve for the determination of quercetin equivalent. The total flavonoid content of the samples was determined from the obtained calibration curve and results are given as µg QE/g dw.

Total antioxidant capacity

Total antioxidant capacity was determined through DPPH and TEAC methods.

DPPH (2,2-diphenyl-1-picrylhydrazyl) method

The antioxidant capacity was measured according to the method based on the free radical scavenging activities of the stable DPPH as described by Nile et al. [23]. The assay is based on the loss of violet color of DPPH solution when reduced by an antioxidant. A solution of 25 µg/mL DPPH in CH3OH was prepared, and the absorption of DPPH solution was measured at 510 nm. Then, different amounts of the sample extracts were added to DPPH solution and kept in dark for 30 min before absorbance measurement at 510 nm. The percentage of DPPH scavenging effect was calculated using the equation:

$$DPPH \,Scavenging \,effect\, \left( \% \right) \,or \,Percent \,Inhibition = \frac{{\left( {A_{0 } - A_{1 } } \right)}}{{A_{0} }} \times 100$$

A0 is the absorbance of the sample free solution, and A1 is the absorbance of the sample containing solution after 30 min. The results of DPPH were given as IC50 (µg/mL). The IC50 values indicate the concentration of the antioxidant substance which inhibits 50% of the DPPH radical in the medium, low IC50 values indicate high antioxidant activity or vice versa.

TEAC (Trolox equivalent antioxidant capacity) method

The free radical-scavenging activity the ABTS (2,21-Azino-bis(3-ethylbenzothiazoline-6-sulfonic) was determined according to the method described by Zulueta et al. [24]. The stock solutions including 7.0 mM ABTS solution and 2.4 mM K2S2O8 allowed stand in the dark at room temperature for 12–16 h. The ABTS·+ solution was diluted with phosphate buffer (pH 7.4) to obtain an absorbance 0.800  ±  0.010 at 734 nm. Then 20 µL of the sample or trolox standard was added to 2.0 mL ABTS·+ solution, and allowed to stand at room temperature for 15 min before the measurement of absorbance at 734 nm, using ABTS·+ solution as the control group. All measurements were performed in triplicated for each sample. The percentage inhibition of ABTS·+ by the sample was calculated according to the formula:

$$\% \,Inhibition = \frac{{\left( {A_{C\left( 0 \right) } - A_{A\left( t \right) } } \right)}}{{A_{C\left( 0 \right)} }} \times 100$$

where AC(0) is the absorbance of the control at t = 0 min, and AA(t) is the absorbance of the (trolox + ABTS·+) or (Sample + ABTS·+) at t = 15 min. The free radical scavenging capacity of the samples were calculated as percent inhibition of ABTS·+. The standard calibration curve was generated using trolox concentration at 1.0–4.0 µg/mL. The antioxidant capacity of the sample was calculated as trolox equivalent (µmol Trolox/g dw).

Analysis of selenium

From a homogenized 20.0 g fresh myrtle fruit, 2.0 g homogenate was transferred to a Teflon bomb. Then, 5.0 mL of HNO3: HClO4 mixture (1:4, v/v) was added and allowed to stand at 100 °C for 12 h. Selenium was analyzed fluorimetrically according to Dogan et al. [25].

Analysis of Cu, Fe, Mn and Zn

To 3.0 g fruit sample 5.0 mL of HClO4 and HNO3 mixture (1:4 v/v) was added, vortexed, and sonicated for 30 min and then left to stand for 24 h. Then, 2.0 mL H2O2 was added to decompose the organic components. The final volume was completed to 25 mL with %1.0 Triton-X 100 solution then the concentration of metals was determined by a flame atomic absorption spectrophotometer [26], which reported to have detection limits 0.03, 0.05, 0.03 and 0.01 mg/L for Cu, Fe, Mn and Zn, respectively [27].

Statistical analysis

All measurements were triplicated and mean standard deviation was determined. The results were subjected to Variance Analysis by SPSS 10.0 for Windows. The level of statistical significance was expressed as p < 0.05.

Results and discussion

Different conservation methods, freezing and drying being the most common ones, are applied to seasonal fruits to protect both their appeal and nutritional value for year round consumer consumption. However, such preservation methods not only affect the physical appearance of fruits but also their nutritional characteristics as well. The study here was carried out in a comparative fashion to determine the vitamins (A, B, C and E), carotenoids (lycopene β-carotene), functional peptides (glutathione, ghrelin), oxidative stress markers (MDA, GSSG), total phenolic and flavonoids and antioxidant capacity (DPPH, TEAC) in wild-type and cultivated-type myrtle fruits under commonly used preservation conditions such as sun-drying, microwave-drying and freezing and how such conditions impacted both the nutritional value and some pharmacological activities these fruits.

The results (Tables 1, 2 and Figs. 1, 2) showed that vitamins A, E, cyanocobalamin, thiamine, nicotine amide, and folic acid in the wild white type myrtle fruits were higher, while riboflavin was lower than in the cultivated white myrtle fruits (p < 0.05). The levels of β-carotene, lycopene, ascorbic acid and pyridoxine were similar in fresh fruits of both wild and cultivated plants (p > 0.05). The highest levels of vitamins and lycopene were found in fresh fruits of both wild and cultivated fruits, while the sun-dried samples had the lowest vitamin and lycopene levels (p < 0.05). The vitamin loss in sun-dried and microwave-dried fruits ranged between 31.5–55%. It is known that, process conditions such as temperature and time are important factors in the degradation level of vitamins [28]. Vitamin loss in microwave-dried myrtle fruits was relatively lower than in sun-dried samples, which in accordance with previous findings that longer exposure of the fruits to sun-drying caused the greatest loss of vitamins [29]. Thus, short processing time in microwave-drying of fruits is reported as an important advantage [30]. Our results in this study showed that both water and fat soluble vitamins in wild and cultivated myrtle fruits (Tables 1, 2 and Figs. 1, 2) were higher than for the same vitamin levels in avocado and apricot [16], jujube fruit [31], monkey diamond [32] and cherry [33].

Table 1 The value of the parameters examined in fresh, frozen, sun and microwave dried wild white Myrtus communis L. fruit
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Table 2 The value of the parameters examined in fresh, frozen, sun and microwave dried cultivated white Myrtus communis L. fruit
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Fig. 1
figure 1

Contents of fat and water soluble vitamins and lycopene in fresh, frozen, sun and microwave dried wild white myrtle samples (for clarity and to bring into scale; vitamin A values multiplied by 10, beta-carotene values multiplied by 5 and lycopene values multiplied by 2, thiamin and riboflavin values divided by 5, vitamin E nicotinamide values divided by 10, Ascorbic acid and folic acid divided by 100)

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Fig. 2
figure 2

Contents of fat and water soluble vitamins and lycopene in fresh, frozen, sun and microwave dried cultivated white myrtle samples (for clarity and to bring into scale; vitamin A values multiplied by 10, beta-carotene values multiplied by 5 and lycopene values multiplied by 2, thiamin and riboflavin values divided by 5, vitamin E nicotinamide values divided by 10, Ascorbic acid and folic acid divided by 100)

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As can be seen from Tables 1, 2 and Figs. 1, 2, vitamin loss depends on the conservation methods of fruits. The least vitamin loss was found in frozen fruits, while the most vitamin loss was found in sun-dried samples. Degradation of vitamins in the sun drying process can be a result of photochemical and enzymatic reactions [34]. Vitamin loss in sun-dried fruit samples is higher than microwave-dried samples. This can be explained by higher energy of sunlight to break down the vitamins and longer exposure time to dry [29]. The loss of vitamins observed by microwaves drying can be explained by very high temperature reach in short time causing thermal degradation of fruits. On the other hand, short drying time with the microwave oven is an advantage in terms of both vitamin loss and time compared with sun drying methods [30]. Myrtle fruit is a good source of vitamins. Most of these vitamins are important in nutritional diet and play a key role in the function of enzymes.

The myrtle fruits were also found to be a rich source of ghrelin, which is an appetite hormone normally associated with animals but recently being identified also in plants [35]. The amount of ghrelin in wild-type myrtle fruits were higher than that in cultivated types. In fresh, frozen, sun and microwave-dried wild fruits the ghrelin levels were 28.80 ± 1.50, 27.30 ± 1.30, 18.80 ± 1.28 and 19.20 ± 1.45 μg/g dw, respectively. The same figures for cultivated myrtle fruits were 18.30 ± 1.10, 18.60 ± 0.95, 11.80 ± 0.71, 12.80 ± 0.90 μg/g dw, respectively (Tables 1, 2 and Figs. 3, 4). A related study reported the amount of ghrelin in Crataegus laevigata (aka. midland hawthorn) fruits grown in different regions was between 18.96–79.96 μg/g [17].

Fig. 3
figure 3

Contents of Ghrelin, GSH, GSSG and MDA, in fresh, frozen, sun and microwave dried wild white myrtle samples (for clarity and to bring into scale; GSH and GSSG values divided by 10, MDA values multiplied by 10)

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Fig. 4
figure 4

Contents of Ghrelin, GSH, GSSG and MDA, in fresh, frozen, sun and microwave dried cultivated white myrtle samples (for clarity and to bring into scale; GSH and GSSG values divided by 10, MDA values multiplied by 10)

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The levels of glutathione (GSH) and its oxidized form (GSSG) are important indicators of cellular redox state and thus cellular and organismal health A perturbation in their balance may cause a multitude of cellular stresses and responses. A continuum of such stress may result deleterious effects not only on cells but whole organism [8]. Our study showed that the fresh fruits of both wild and cultivated myrtle were rich source of GSH (Tables 1, 2 and Figs. 3, 4). Compared to a previous study [36] reporting the levels of GSH in banana (Musa paradisiaca L.), myrtle fruits had more than 10 times higher GSH levels. Similarly, the levels of GSH in myrtle fruits were considerably higher than that in asparagus, avocado, apple, pear and strawberry fruits [37].

Preservation of the myrtle fruits either by sun or microwave-drying decreased their GSH content, while GSSG levels were significantly increased (p < 0.05) (Tables 1, 2 and Figs. 3, 4).

Both glutathione and ghrelin are known as peptides. Preservation methods applied to foods can significantly affect the biological activity of peptides. Ultrasound, heat, and irradiation processing might affect protein structure and functions. In addition, these processes may cause Maillard reactions in food (Davis et al.). As a result of the factors mentioned above, might leads to changes in the amount of peptides.

An imbalance of GSH/GSSG in favor of GSSG is indicative of oxidative stress in cells and tissues [38]. Malondialdehyde (MDA) is also a cellular stress indicator and is formed as a result of lipid peroxidation caused by free radicals [39]. Our study showed that the amount of MDA in wild and cultivated myrtle fruits ranged between 5.73 ± 0.51–7.76 ± 0.35 and 4.50 ± 0.21–6.05 ± 0.58 μg/g dw, respectively (Tables 1, 2 and Figs. 3, 4). There was a statistically significant increase in MDA amounts upon drying processes in both wild and cultivated myrtle fruits (p < 0.05), a result supported by a previous study reporting that the amount of MDA varied between 10–22 nmol/g depending on the level of moisture removed from apricot fruits upon IR and microwave drying [40]. Both the increase in the amount of MDA and the decrease in GSH/GSSG ratio confirm the oxidative stress during drying processes of the fruits (p < 0.05).

Phenolic compounds, the largest group of phytochemicals, display a wide range of biochemical and pharmacological activities. The total amount of phenolic substance (37.30 ± 2.10 μg GAE/g dw) in our study in wild type fresh myrtle fruits was significantly higher than that in cultivated ones (26.9 ± 1.45 μg GAE/g dw, p < 0.05). Drying caused a statistically insignificant decrease (p > 0.05) in phenolic substances (Tables 1, 2 and Fig. 5). The amount of total flavonoids in fresh, frozen, sun and microwave-dried wild myrtle fruits were 22.17 ± 1.15, 21.85 ± 0.95, 19.62 ± 0.95 and 19.40 ± 0.75 μg QE/g dw, respectively. These figures were found to be significantly higher (p < 0.05) than the ones determined the total flavonoids in fresh, frozen, sun and microwave dried cultivated myrtle fruits 17.74 ± 1.10, 17.14 ± 0.95, 14.17 ± 0.85 and 13.11 ± 0.75 μg QE/g dw, respectively (Tables 1, 2 and Fig. 5). The highest flavonoid loss was observed in microwave dried fruits, while the lowest loss was in frozen fruits.

Fig. 5
figure 5

Contents of total flavonoids in fresh, frozen, sun and microwave dried wild and cultivated white myrtle samples

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There have been contradictory reports on the effect of drying on phenolic compounds in various fruits [22, 41, 42], which may be attributed to compound and fruit type, different production and processing methods and environment. It was reported that drying caused phenolic compound degradation and formation of new intermediates and by products [43] and drying conditions may cause up to 96% loss in the total amount of flavonoids [44]. It was shown that the drying significantly impacted the concentration of phenolic compounds. This may be explained by the high temperature in microwave drying, as exposing phenolic compounds to high temperatures was shown to induce a high level of decomposition [45]. Also, the amount of phenolics and flavonoids determined was shown to be dependent of solvents used for the extraction [46].

The trolox equivalent antioxidant capacity (TEAC) and the DPPH radical scavenging assays were run for the total antioxidant activity testing. IC50 values were found by the DPPH method, while trolox equivalent was calculated by TEAC method. From IC50 and TEAC values, it could be inferred that the wild myrtle fruits had higher antioxidant capacity than cultivated ones (Tables 1, 2 and Fig. 6). The IC50 values in wild myrtle fruits ranged between 39.21 ± 1.25 and 44.30  ±  2.10 μg/mL on the other hand the figures were between 57.50  ±  2.25 and 63.88  ± 2.45 μg/mL in cultivated types, which is a significantly higher than the wild myrtle fruits (p < 0.05). IC50 values indicating higher antioxidant activity in the wild type fruits than that in cultivated fruits. TEAC values of fresh wild and cultivated myrtle fruits were 295.10 ± 12.50 and 269.0  ±  10.50 μmol trolox/g dw, respectively (Tables 1, 2 and Fig. 7). Sun-drying caused a significant (p < 0.05) decrease in the antioxidant capacity of both wild and cultivated fruits. In this context, IC50 values of mangosteen, orange, pamelo, grape and papaya fruits were found in the range of 11.18–32.8 mg/mL [47]. A previous study also carried out on myrtle fruit reported that the total amount of phenolic, flavonoid substance, antioxidant capacity (IC50) values in the essential oil from white myrtle fruit were 53.0 ± 2.70 mg GAE/g, 15.0  ±  1.90 mg RE/g; (RE: rutin equivalent) and 2.8 mg/mL, respectively [48]. Our study showed that both the wild and cultivated myrtle fruits had substantially higher trolox equivalents than rosehip [49].

Fig. 6
figure 6

Contents of total antioxidant capacity (IC50 value) in fresh, frozen, sun and microwave dried wild and cultivated white myrtle samples

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Fig. 7
figure 7

Contents of total antioxidant capacity (TEAC value) in fresh, frozen, sun and microwave dried wild and cultivated white myrtle samples

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Trace elements play pivotal roles in physiological processes. Zinc is essential element as a catalytic, structural and regulatory ion through its function in homeostasis, immune response, oxidative stress, apoptosis and ageing. It functions as a cofactor for numerous enzymes, including those involved in DNA and RNA replication and protein synthesis [50]. Cu is crucial for the normal development of the brain, nervous system, bones and connective tissue. As for Zn, Cu allows many critical enzymes to function properly and has critical role in hemoglobin synthesis [51]. Fe is necessary for growth, development, normal cellular functioning, and synthesis of some hormones [52]. Mn plays role in fat and carbohydrate metabolism, calcium absorption, and blood sugar regulation. Selenium is a vital trace element for human health and is found in the active site of selenoproteins as selenocysteine. Se is also the cofactor of glutathione peroxidase and thioredoxin reductase enzymes [53]. Thus, adequate levels of these trace elements in our diet are essential for normal cellular and bodily functions.

Wild-type myrtle fruits had significantly (p < 0.05) higher Se, Fe, Cu and Mn levels (0.58  ±  0.018, 205.14  ±  11.70, 228.06  ±  10.80, 37.22  ±  2.15 and 24.3  ±  1.55 μg/g dw, respectively) than cultivated myrtle fruits (0.50  ±  0.02, 228.91  ±  12.70, 162.64  ±  10.85, 33.32  ±  1.50 and 15.00  ±  1.10 μg/g dw, in that respectively) (Tables 1, 2 and Fig. 8), while the difference in the amount of Zn in two fruits was statistically insignificant (both at around 220 μg/g dw) (p > 0.05). These figures for Fe, Cu and Mn were substantially (from one order to more than three order of magnitude) higher than same elements found for apple and cherry fruits [54]. Also, Se found in myrtle fruits was about 50, 20, 116, 18 times higher than Se in apples, oranges, mangoes and figs, respectively [55].

Fig. 8
figure 8

Contents of selenium, zinc, iron cupper and manganese in cultivated white myrtle samples (for clarity and to bring into scale; selenium values multiplied by 10, zinc and iron values divided by 10,)

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Conclusions

The wild-type myrtle fruits had generally higher levels of vitamins, phenolics, antioxidants, and some elements than the cultivated-type myrtle fruits. No significant difference was observed in fresh and frozen myrtle fruits in terms of the biochemical parameters examined. In this context, microwave-drying was determined to be more advantageous than sun-drying, since the process time in the former is shorter. The study showed that the most appropriate method of preservation of the myrtle fruits was freezing.