THE MINERAL COMPOSITION OF WHITE AND BLACK MULBERRY FRUITS (Morus alba) WAS STUDIED USING INDUCTIVELY COUPLED PLASMA OPTICAL EMISSION SPECTROMETRY (ICP-OES)

ABSTRACT

The mineral composition of two types of Morus alba fruits was analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES).

The content of  28 elements in the fruits of the plant was studied. The highest amount of mineral substances was found in the black mulberry fruits, amounting to 3436.537 mg per 10 g. The following macroelements were identified in both types of Morus alba fruits: K, Ca, Mg, Na, P, and S. Potassium was the predominant element in the studied fruits. Micronutrients such as Fe, Al, Zn, Mn, S, Li, and B were also detected. Although iron is considered a micronutrient, its content exceeded that of Ca, Mg, Na, P, and S.

The conducted analyses showed that Morus alba fruits are a source of potassium, iron, calcium, magnesium and sodium.

АННОТАЦИЯ

Минеральный состав двух видов плодов растения Morus alba был исследован методом оптической эмиссионной спектрометрии с индуктивно связанной плазмой (ICP-OES). Изучено содержание 28 элементов в составе плодов растения. Наибольшее количество минеральных веществ было обнаружено в плодах чёрной шелковицы и составило 3436,537 мг на 10 г. В двух видов плодов растения Morus alba обнаружены следующие макроэлементы K, Ca, Mg, Na, P, S. В изученных плодах преобладает калий. Также обнаружены микроэлементы, такие, как, Fe, Al, Zn, Mn, S, Li и В. Железо хотя является микроэлементом, содержание его больше чем, Ca, Mg, Na, P и S. Проведённые анализы показали, что плоды Morus alba являются источником калия, железа, кальция, магния и натрия.

Keywords: mulberry, fruits, macro- and microelements, inductively coupled plasma mass spectrometry, potassium, iron.

Ключевые слова: шелковица, плоды, макро- и микроэлементы, масс-спектрометрия с индуктивно-связанной плазмой, калий, железо.

Introduction

Mulberry (Latin: Morus) fruit is sweet, healing, and rich in various vitamins. In folk medicine, mulberry has long been used to treat various illnesses. In Uzbekistan, mulberries have been cultivated and used in traditional medicine since ancient times. They are consumed when fully ripe, and various products such as sherbet, jam, and raisins are made from the fruit. Mulberry leaves are used as food for silkworms [1, р. 43].

The leaves and bark of the mulberry tree are also rich in various biologically active substances. The leaves contain flavonoids, vitamins, carotene, essential oils, and organic acids, while the bark contains tannins [[2, р.24; 3, р.44]. Mulberry fruit is juicy, containing up to 82.9–86.2% water. When dried and consumed, its sweetness increases [4, р.49]. Mulberry raisins contain between 73.29% and 83.71% sugar. Additionally, mulberries are rich in vitamins B, C, E, K, and PP. Therefore, it is recommended for people who are weakened by illness or prone to frequent colds to consume it regularly [5, р.33; 6, р.48].

Materials and methods

An accurately weighed 0.1 g sample was transferred into Teflon autoclaves. Then, 3 mL of purified concentrated nitric acid (HNO₃) and 2 mL of purified hydrogen peroxide (H₂O₂) were added. The autoclave was sealed and placed in a Berghof microwave digestion system (Speed Wave Xpert or a similar type of microwave oven). A predefined program was executed via the device interface to initiate digestion.

The system automatically controlled and monitored the number of autoclaves used, as well as the internal temperature and pressure. Process parameters were tracked in real-time via a liquid-crystal display. The digestion was carried out under wet digestion conditions at a minimum temperature (T) of 52°C and a maximum temperature (T) of 225°C, with pressure (P) reaching up to 38 bar, for a duration of 35-40 minutes.

Preparation of the Sample for Analysis: The mineral composition of Morus alba (white mulberry) fruits was studied using inductively coupled plasma optical emission spectrometry Agilent 5800 (ICP-OES).

Results and discussions

The concentrations of macro- and microelements in two different fruit varieties of Morus alba were determined. A total of 28 elements were analyzed in the plant material. The highest mineral content was found in black mulberry (Morus nigra), reaching 3436.537 mg/10 g (Table 1) [7, р.52].

Table 1.

Mineral Composition and Content in Morus alba Fruits (mg/10 g)

The amount of macro elements in white mulberry fruit was 1650.913 mg/10 g, and in black mulberry fruit, it was 1767.289 mg/10 g. The order of macro elements in white mulberry fruit decreases as follows: K > Ca > Mg > Na > P > S, and in black mulberry fruit: K > Ca > Mg > Na > P > S. The fruits of the Morus alba plant contain potassium, calcium, magnesium, sodium, aluminum, and sulfur elements [8, р.54]. In all samples, potassium and iron were found to be in the highest amounts.

Figure 1. Macro element content (mg/10 g) in white and black mulberry fruits of the Morus alba plant

In addition, the number of microelements in the fruits of the Morus alba plant was also determined. The number of microelements was found to be higher in black mulberry fruits compared to white mulberry fruits. Elements such as Te (tellurium), Sb (antimony), Sn (tin), and other microelements were not detected [9, р.26]. Cobalt was found in small amounts in both white and black mulberry fruits. The amount of iron among the microelements was determined to be 578.170 mg/10 g in white mulberry and 689.077 mg/10 g in black mulberry. The potassium to iron ratio in white and black mulberry fruits of Morus alba was 2.85:1 and 4.66:1, respectively. The calcium to iron ratio was 0.57:1 in white mulberry and 0.66:1 in black mulberry fruits [10, р.396].

Figure 2. Macro element content (mg/10 g) in white and black mulberry fruits of the Morus alba plant

The amounts of toxic elements such as arsenic and lead were also studied. Arsenic was detected in both white and black mulberry fruits of the plant (Figure 3). Lead was found in the amount of 0.009 mg/10 g in white mulberry and 0.011 mg/10 g in black mulberry. No information has been provided regarding toxic elements in Morus alba plants. The fruits of Morus alba were found to contain almost the same number of elements and are distinguished by their high content of macro- and microelements.

Figure 3. Heavy metal content (mg/10 g) in the white and black mulberry fruits of the Morus alba plant

Conclusion. As a result of studying the mineral composition of white and black mulberry fruits of the Morus alba plant using inductively coupled plasma optical emission spectrometry (ICP-OES), the quantities of 28 elements were identified in the fruits. It was determined that calcium has the highest concentration among the elements in the fruit. Among the microelements, manganese, iron, and aluminum were found in higher amounts compared to the other elements. The Morus alba plant can be used in the preparation of various biologically active supplements and medicinal products.

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