The Effect of the Addition of Selected Juices on the Content of Aluminum in Tea Infusions and Health Risk Assessment in the Polish Population

Abstract

Tea is a plant rich in compounds that positively impact human health. Still, it also contains large amounts of aluminum, which is toxic to humans and passes into the infusion during brewing. The presented research aims to determine the effect of adding lemon, Japanese quince, and quince juice to infusions of various types of teas on their aluminum content. It should be emphasized that research on the impact of Japanese quince and quince juices has not yet been published. Exposure to exceeding the safe level of aluminum consumption from tea infusions was also assessed. It has been shown that adding juices that lower the pH of infusions increases the aluminum content by up to 150%. The main factor influencing the increase in the aluminum content in tea infusions with additives is the lowering of the pH value, and other ingredients present in the juices do not have a significant impact. The health risk assessment indicates the possibility of adverse health effects from aluminum consumption, especially from black and green tea infusions with the addition of Japanese quince and lemon juices. It has been shown that quince juice can be recommended as an addition to tea infusions because it causes the smallest increase in aluminum content in the infusion among the juices tested.

1. Introduction

An infusion made from the leaves of a shrub or tea tree (Camellia sinensis (L.) Kuntze or Camellia assamica L.) is one of the most frequently consumed drinks worldwide. The first records of tea consumption came from China 5000 years ago. It was brought to Europe in the 18th century [1]. In 2008, it was estimated that approximately 20 billion cups of tea were consumed worldwide [2]. Depending on the season, it is consumed in different amounts. In winter, tea consumption in Poland represents more than 40% of all beverages consumed during this season. In summer, however, the consumption of this drink is reduced to 25%. Generally, we drink tea 2–3 times a day; however, approximately 20% of consumers drink tea more often, 4–5 times daily [3]. Such frequent consumption of tea is due to its sensory and nutritional value. Tea owes its popularity to, among others, health-promoting values resulting from the high content of polyphenols, mainly flavonoids and phenolic acids, constituting approximately 30% of the dry weight of tea leaves [4]. The content of these compounds is found in green tea leaves, while in black tea, this amount constitutes 10% of the dry weight of the leaves [5]. The most abundant polyphenols in tea leaves and infusions, in addition to their antioxidant properties, have anti-inflammatory, antibacterial, and antiallergic properties. Tea infusions also have a beneficial effect on the circulatory system. Regular consumption of these drinks may help reduce the incidence of cardiovascular disease, including ischemic heart disease and stroke [6]. Regular consumption of tea, especially green tea, significantly reduces cholesterol levels, especially the LDL fraction, preventing its oxidation and lowering blood pressure [1]. Although there is a lot of research and evidence that tea contains many ingredients that have a beneficial effect on the human body, it also contains ingredients that are harmful to the body, which has not yet been thoroughly researched but is introduced to the body with the consumption of tea and accumulates in it. Their impact on the body’s condition is still carefully researched [7].

Many studies have shown that tea is a plant rich in aluminum. This is a consequence of cultivating shrubs and tea trees on acidic soils and the processing processes they are subjected to [8]. It develops nicely in soil with a pH of 3.5 to 5.6. In such an environment, aluminum becomes more soluble and, therefore, more available to plants. However, in the case of these plants, aluminum is a factor that stimulates their growth. By modifying the method of growing tea plants, its content can be reduced. However, this is not beneficial for the development and efficiency of this plant. In addition, the aluminum content is influenced by the age of the plant, the altitude of the plantation, the general accumulation of aluminum in the substrate, and the quantity and quality of acid rain. Aluminum in tea accumulates mainly in the leaves. The aluminum content in young leaves and buds is lower than in older leaves. It ranges from 300 to 2500 mg/kg compared to older leaves, whose content exceeds 5500 mg/kg of raw material [9]. The negative effect of aluminum on the nervous system, i.e., its neurotoxic effect, was discovered in the 1880s. Until then, it was considered entirely non-toxic [10]. Since then, scientists have repeatedly observed that aluminum is present in the brain tissue of Alzheimer’s disease patients in more significant amounts than in people who do not suffer from the disease. The accumulation of aluminum in the brain over time leads to neuronal damage and reduced function of this organ [11]. It accumulates mainly in the parts responsible for memory—the hippocampus and the temporal lobe. Aluminum toxicity manifests itself in the weakening of acetylcholine synthesis, which is responsible for, among others, the ability to learn and remember [12]. Higher levels of aluminum and fluoride were related to dementia risk in a population of men and women [13]. Moreover, it also contributes to the formation and accumulation of a toxic peptide—β-amyloid [14]. The articles most cited in the world literature suggest that aluminum exposure is associated with Alzheimer’s disease, Parkinson’s disease, dialysis encephalopathy, amyotrophic lateral sclerosis, neurodegenerative changes, cognitive impairment, bone damage, oxidative alterations, and cytotoxicity [15].

As a drink with a centuries-old tradition, tea remains the subject of constant experimentation in the search for new flavors and health benefits. One of the interesting directions of exploration for tea lovers is the addition of various fruit juices, such as lemon juice (Citrus limon), common quince (Cydonia oblonga Mill.), or Japanese quince (Chaenomeles japonica (Thunb.) Lindl. ex Spach), to give the infusion not only a new taste dimension but also potential health value. According to Zimmermann and Gleichenhagen [16], the low pH of tea (3–4.8), obtained by adding citric acid, ascorbic acid, or using a phosphate buffer, causes a 20% increase in the content of flavanols. Researchers suggest that adding lemon to tea increases the extraction of polyphenolic compounds that positively affect the body and recommend drinking tea with lemon. To preserve the properties of tea resulting from the presence of catechins, mainly in green tea, it should be brewed in water with a pH of about 3–5 [17]. Therefore, to increase the degree of extraction of polyphenols from tea leaves, it would be beneficial to acidify the solution, e.g., by adding fruit juice. Moreover, it has been shown that the amount of aluminum available during plant growth correlates with the content of catechins and other secondary metabolites in the leaves [18,19]. The addition of lemon juice affects the pH of the tea infusion, which in turn may affect the solubility of various mineral substances, including aluminum. In an acidic environment (present when lemon is added), some mineral compounds, including aluminum, may be more soluble [20,21,22]. This is important because, given the widespread consumption of this drink around the world, it may pose a real risk of overdose of this toxic element. Based on the information mentioned above, a conclusion should be drawn about the need for research on how to reduce the aluminum content in tea infusions. However, such research has not been undertaken because the literature review found only one article on this topic. Mossion et al. showed that the use of water with a higher mineral content for brewing tea reduces the extraction of aluminum into the infusion [23].

The study aimed to investigate the effect of adding lemon, quince, and Japanese quince juice to infusions of various types of tea on aluminum content and assess exposure to exceeding the safe aluminum consumption level. The influence of the addition of quince and quince juices on the aluminum content in various types of tea infusions was examined for the first time. The effect of adding lemon juice on the aluminum content in tea infusions has been described in scientific articles [20,21,24,25,26]. They indicate that the main factor influencing the increase in aluminum content in the infusion is the lowering of pH. However, we have not found an article that describes an experiment that would allow us to answer the question of whether other factors, e.g., the composition of juices, also influence the increase in aluminum content. Therefore, in our article, we carried out for the first time the determination of the aluminum content in infusions to which, instead of juice, a citric acid solution with an acidity identical to the acidity of selected fruit juice was added at the brewing stage to check whether the increase in aluminum content in the infusions was influenced by other factors originating from the juice.

2. Materials and Methods

2.1. Materials

The research material consisted of 5 tea samples of various types from different manufacturers purchased in Lublin (Poland) stores. The research material consisted of loose-leaf teas: green (country of origin: Sri Lanka), pu-erh (country of origin: China, Yunnan Province), and white (country of origin: China, Fujian Province) and two black teas: loose-leaf (country of origin: China, Yunnan Province) and granulated (country of origin: Kenya). All loose-leaf teas used in the research were sieved. The fraction used in further analyses ranged from 1.5 to 2 mm.

To obtain a homogeneous sample of lemon juice (Citrus limon), 1 kg of fruit was purchased. Then, after cutting, the juice was squeezed by hand. The juice thus obtained was vacuum filtered using filters with a pore size of 0.45 µm. The clear juice was poured into a dark glass bottle, closed, and placed in the refrigerator. Juice from Japanese quince (Chaenomeles japonica (Thunb.) Lindl. ex Spach) and common quince (Cydonia oblonga Mill.) was purchased from a local store. Both juices were made from organically grown fruit.

2.2. Preparation of Tea Infusions

The tea infusions were prepared according to PN-ISO 3103:1996 Tea—Preparation of liquor for use in sensory tests. In short, 2 g of tea leaves was poured with 100 mL of deionized water (Hydrolab system HLP10p, Straszyn, Poland) at 100 °C into a cup and brewed under cover for 6 min. Then, the infusion was vacuum filtered through a filter with a pore size of 0.45 µm into a volumetric flask, and after cooling to room temperature, deionized water was added to make up the 100 mL volume.

The tea infusions with the addition of selected juices were prepared as follows. At boiling point, 98 mL of distilled water was added to beakers with 2 g of tea leaves weighed, followed by 2 mL of juice. The mixture was brewed and covered for 6 min according to the PN-ISO 3103:1996 standard [27]. The obtained infusions were filtered as in the case of infusions without the addition of juice. These activities were performed three times for each tea.

An additional test was carried out in which 1, 2, 3, 4, and 5 mL of lemon juice were added to similarly prepared black tea samples (control sample) to determine the change in aluminum content depending on the amount of lemon juice added to the brewing stage.

2.3. Determination of the Titratable Acidity of the Juices

Determination of the titratable acidity of the juices was made based on the PN EN 12147:2000 standard [28]. The principle of the method is to determine titratable acidity via potentiometric titration of the tested product with a standard sodium hydroxide solution to a pH value of 8.1. The obtained titratable acidity value was then converted into the content of anhydrous citric acid by multiplying the obtained value by the coefficient appropriate for individual acids based on the information included in the PN EN 12147:2000 standard. The obtained result was expressed in g/L of product.

2.4. Determination of the Active Acidity (pH) of the Prepared Tea Infusions

After cooling the prepared infusions, the pH was measured using a SevenEasy pH meter from Mettler Toledo. The pH meter was previously calibrated using buffers with pH 7.00 ± 0.02 and then 4.01 ± 0.02 from Mettler Toledo. pH measurement was performed for all infusions, both with and without additives. For this purpose, a solution was used that allowed the pH meter electrode to be freely immersed, and measurements were made until the reading stabilized.

2.5. Determination of the Aluminum Content in the Tea Infusions

The aluminum content was determined using inductively coupled plasma ionization mass spectrometry (ICP-MS) according to the methodology described by Milani et al. [29]. A device manufactured by Varian (Palo Alto, CA, USA), model 820 MS, was used, operating under the control of the “ICP-MS Ekspert” software version 2.1 b107. The operating parameters of the apparatus are presented in

Table 1. Operational conditions for ICP-MS and used for aluminum quantification.

Parameter	Value
The isotope being studied	27
Plasma generator power	1.4 kW
Ar flow through the atomizer	0.97 L/min.
Gas flow in the plasma	16 L/min.
A unit of count	counts per second
Fog chamber temperature	3 °C
Number of sample scans	15
Repetitions	3

. A solution of nitric acid (1.4 g/mL) was added to the analyzed infusions in 0.5 mL per 100 mL and then diluted with water before measurement. The correctness of the analysis was confirmed by determining the aluminum content in the certified reference material (Enviro-Mat Waste water, High EU-H-4, SCP SCIENCE) and comparing the obtained result of 411 ± 5 µg/mL with the certified value of 418 ± 7 µg/mL. The aluminum content was determined in deionized water used to prepare the infusion, in citric acid solutions, and in juices added to the infusions to subtract the amount of aluminum not originating from tea. Both in deionized water and citric acid solutions, the aluminum content was below the limit of quantification, while in lemon, quince, and Japanese quince juices, it was 0.13 µg/mL, 0.11 µg/mL, and 0.07 µg/mL, respectively.

2.6. Statistical Analysis

The data are presented as the means of three measurements ± standard deviation (SD). Data were analyzed using one-way ANOVA, followed by Duncan’s test, using the SAS statistical system (SAS version 9.1; SAS Inst., Cary, NC, USA). The significance of all the tests was set at p ≤ 0.05.

2.7. Estimation of Health Risk

The health risk assessment (noncarcinogenic hazard) related to the ingestion of aluminum from the tea infusions was performed using the target hazard quotient (THQ) calculated by the formula [30]:

THQ = CDI/RfD

(1)

where the chronic daily intake (CDI) is the estimated amount of aluminum intake per kilogram of body weight, and the RfD is the oral aluminum intake reference dose of 0.143 (mg/kg/day). The RfD value was determined based on the tolerable weekly intake (TWI) established at the level of 1 mg/kg/week by the European Food Safety Authority (EFSA) [31]. TWI was established due to the accumulation of aluminum in the human body. A THQ of <1 indicates an insignificant risk level, whereas a THQ of >1 implies a potential non-cancer-causing health impact.

The CDI value was calculated using the equation:

CDI = (C × DI × EF × ED)/(BW × AT)

(2)

where C is the aluminum concentration in tea infusion (mg/L), DI is the average daily intake rate of tea (L/day), EF is exposure frequency (day/year), ED is the exposure duration (year), BW is body weight (kg), and AT is the averaging time (days). The health risk assessment was carried out with the division of the population in terms of age and gender. The average daily intake of the tea infusion was determined based on sufficient water intake for a given population group, assuming that 70% of this intake is provided in the form of liquids and that 50% of these liquids are provided in the form of tea infusion. The value of the daily consumption of tea infusion determined in this way is presented in Table 1 and marked with the abbreviation DI50%. The division of the population into groups and the adopted values of body weight and the value of sufficient water intake were adopted in accordance with the nutritional standards for the Polish population [32] and are presented in

Table 2. Data used to calculate chronic daily intake of aluminum from the tea infusion [32].

	The Exposure Duration ED (Year)	Body Weight BW (kg)	Average Daily Intake Rate of Tea DI50% (L/Day)	Adequate Intake of Water (L)
Kids	3	12	0.438	1.25
	6	19	0.560	1.60
	9	27	0.613	1.75
Girls	12	38	0.665	1.90
	15	51	0.683	1.95
	18	56	0.700	2.00
Boys	12	38	0.735	2.10
	15	54	0.823	2.35
	18	67	0.875	2.50
Women	81	45	0.700	2.00
	81	55	0.700	2.00
	81	65	0.700	2.00
	81	75	0.700	2.00
Men	74	55	0.875	2.50
	74	65	0.875	2.50
	74	75	0.875	2.50
	74	85	0.875	2.50

.

3. Results and Discussion

3.1. Acidity of the Analyzed Juices and Tea Infusions

The juices’ acidity was measured using potentiometric titration at the initial research stage. Lemon juice had the highest titratable acidity of 626.56 mmol ± 14.85 H⁺/L. The titratable acidity of Japanese quince juice was 583.47 ± 12.49 mmol H⁺/L, while that of quince juice was only 41.43 ± 2.57 mmol H⁺/L. When converting the titration acidity result into citric acid, the results were 40.1, 37.3, and 2.7 g/L for lemon juice, Japanese quince, and quince, respectively. Based on the result of determining the titratable acidity of juices and converting the obtained value into the citric acid content, this acid’s corresponding solutions were prepared. These solutions were used to prepare tea infusions to determine the aluminum content and compare its influence on this parameter with the impact of adding selected juices. When preparing infusions with the addition of citric acid solution, the steps described for preparing infusions with juices were followed. Higher titratable acidity is usually associated with a lower pH, which was also observed in the results. Therefore, lemon juice had the lowest pH (pH = 2.35 ± 0.03). Japanese quince juice had a pH value of 2.65 ± 0.02, and quince juice had a pH of 3.8 ± 0.02.

According to the recommendations of the Association of the Industry of Juices and Nectars of the European Union, the titratable acidity of lemon juice converted into citric acid should range from 44.8 to 62.0 g/L [33]. The result obtained is lower than these recommendations but consistent with the results of research published by Lorente et al., in which they tested 92 samples of fresh and 92 samples of reconstituted lemon juices, obtaining a range of titratable acidity from 35.1 to 78.1 g/L [34]. The tested titratable acidity of Japanese quince juice was within the range determined in published studies, which is 26–56 g/L [35]. Quince juice had the lowest titratable acidity, which is confirmed in the literature. However, the obtained titratable acidity value converted to citric acid was lower than the literature data, with it ranging from 3.8 to 7.6 g/L [36,37,38]. This may be because, in published works, fresh quince juice is most often tested, and the juice used in our research is commercially available. It was decided to use commercially available Japanese quince and quince juices due to the poor availability of fresh fruit. At the same time, it allowed us to reproduce the most likely scenario from the consumer’s point of view.

In the next stage, tests were conducted to determine the volume of juices added to the tea infusion. It was decided to use juice with the highest titratable acidity added to the most frequently consumed black leaf tea. Figure 1 shows how the aluminum content changes depending on the amount of lemon juice added to black tea during brewing. The presented data indicate that 2 mL of added lemon juice results in an almost complete increase in the aluminum content in the infusion. Larger volumes of lemon juice added during brewing do not cause a statistically significant increase in the content of the analyzed element in the infusion. Therefore, it was determined that the volume of added juices used during further studies would be 2 mL.

Table 3. Mean and SD pH values of tea infusions without additives and with additions of juices and citric acid solutions with the titratable acidity of the juices used. Values with different letters (a, b, c, etc.) in the same column are significantly different (p < 0.05), as determined using Duncan’s test.

	White Tea	Black Granulated Tea	Black Leaf Tea	Pu-Erh	Green Tea
pH of infusions without additives	5.6 ± 0.02 a	5.01 ± 0.01 a	5.02 ± 0.01 a	5.65 ± 0.02 a	5.51 ± 0.01 a
pH of infusions with quince juice	5.21 ± 0.02 c	4.8 ± 0.01 b	4.82 ± 0.02 c	5.32 ± 0.02 c	5.18 ± 0.01 c
pH of infusions with citric acid solution (quince)	5.35 ± 0.02 b	4.77 ± 0.02 c	4.91 ± 0.02 b	5.41 ± 0.02 b	5.21 ± 0.02 b
pH of infusions with lemon juice	3.65 ± 0.02 f	3.55 ± 0.02 f	3.57 ± 0.02 e	3.47 ± 0.02 f	3.54 ± 0.02 f
pH of infusions with citric acid solution (lemon)	3.63 ± 0.01 f	3.48 ± 0.02 g	3.58 ± 0.01 e	3.4 ± 0.02 g	3.47 ± 0.02 g
pH of infusions with Japanese quince juice	3.83 ± 0.01 e	3.74 ± 0.04 e	3.61 ± 0.04 e	3.81 ± 0.03 e	3.76 ± 0.02 e
pH of infusions with citric acid solution (Japanese quince)	3.99 ± 0.02 d	4.03 ± 0.01 d	3.78 ± 0.02 d	3.91 ± 0.02 d	3.88 ± 0.02 d

presents the tea infusions’ active acidity (pH) measurements with additives and infusions constituting control samples. Based on the measurements of infusions without additives, the teas can be ranked with increasing pH as follows: black granulated < black leaf < green < white < pu-erh. The pH values of these teas ranged from 5.01 to 5.65 and were consistent with the literature data [39,40,41]. As a result of adding juices and citric acid solutions to the infusions, a decrease in the pH value was observed. The most minor percentage decrease, ranging from 2.2% to 7%, was observed in infusions with quince juice and the corresponding citric acid solution. This is related to it having the lowest titratable acidity. More significant pH drops ranging from 28.7% to 39.8% and 19.6% to 32.6% were observed for adding lemon juice and Japanese quince, respectively, along with the corresponding citric acid solutions. The lemon and Japanese quince juices used in the research were characterized by similar titratable acidity; therefore, their effect on lowering the pH of the infusions is also similar. Reducing the pH value after adding additives with low pH and high titratable acidity is natural and is confirmed in the literature. However, a comparison of the obtained results with the literature data does not lead to any conclusions because the additives used by other authors had different forms (solutions of citric, nitric, and ascorbic acids of various, often unknown concentrations; lemon juice of unknown acidity) and were added in various amounts [21,25,39,42].

3.2. Aluminum Content in the Tea Infusions

Table 4. Mean and SD aluminum concentration (mg/L) in tea infusions without additives and with additions of juices and citric acid solutions with the titratable acidity of the juices used. Values with different letters (a, b, c, etc.) in the same column are significantly different (p < 0.05), as determined using Duncan’s test.

	Aluminum Content (mg/L)
	White Tea	Black Granulated Tea	Black Leaf Tea	Pu-Erh	Green Tea
Infusions without additives	2.33 ± 0.14 d	6.46 ± 0.2 c	3.16 ± 0.29 d	1.08 ± 0.08 d	5.71 ± 0.18 c
Infusions with quince juice	3.28 ± 0.19 c	6.92 ± 0.59 c	3.4 ± 0.3 d	1.25 ± 0.09 cd	7.06 ± 0.72 b
Infusions with citric acid solution (quince)	3.97 ± 0.07 b	6.56 ± 0.21 c	3.41 ± 0.17 d	1.33 ± 0.03 c	6.83 ± 0.2 b
Infusions with lemon juice	4.43 ± 0.17 a	9.04 ± 0.27 b	5.53 ± 0.21 a	2.68 ± 0.09 a	10.2 ± 0.3 a
Infusions with citric acid solution (lemon)	4.55 ± 0.22 a	9.18 ± 0.23 b	5.61 ± 0.38 a	2.69 ± 0.12 a	9.92 ± 0.27 a
Infusions with Japanese quince juice	4.51 ± 0.37 a	8.93 ± 0.31 b	4.95 ± 0.23 b	2.43 ± 0.18 b	10.05 ± 0.82 a
Infusions with citric acid solution (Japanese quince)	4.69 ± 0.2 a	10.34 ± 0.1 a	4.38 ± 0.31 c	2.61 ± 0.11 ab	10.48 ± 0.43 a

shows the results of determining the aluminum content in infusions of various teas without additives and infusions with juices and citric acid solutions. In infusions without additives, the aluminum content ranged from 1.08 to 6.46 mg/L, and the teas can be ranked with increasing aluminum content in the infusion as follows: pu-erh < white tea < black leaf tea < green tea <granulated black tea. Many factors influence the aluminum content in tea infusions, mainly the age of the leaves at the time of harvest, the genetic aspects of the plant, soil and atmospheric conditions, and the method of preparing the infusion. Based on numerous studies aimed at determining the aluminum content in tea extract, despite differences in extraction conditions, the determinations are similar and oscillate in the range of 1–6 mg/L [43]. The addition of quince juice did not cause a statistically significant increase in the aluminum content in the infusion in the case of pu-erh tea, black granulated tea, and loose-leaf tea. An increase in aluminum content was observed in white and green tea, 40.8% and 23.6%, respectively. The addition of citric acid with the acidity of quince juice had a very similar effect on the aluminum content in the infusions. The main difference is the increase in aluminum content compared to infusions without the addition of 23.1% in the case of pu-erh tea and 70.4% in the case of white tea. It was also shown that there were no statistically significant differences between the aluminum content in the infusions of pu-erh tea, black loose leaf, and granulated tea and green tea with quince juice and the corresponding citric acid solution. In the case of the influence of adding lemon and Japanese quince juices and their corresponding citric acid solutions, significantly greater increases in aluminum content were found in the infusions of all types of teas compared to quince juice. These increases ranged from 38.2% to 149.1% in relation to the initial aluminum content. It was also shown that there were no statistically significant differences in the aluminum content in infusions with these additions for white and green teas, and in the case of pu-erh and granulated black teas, these differences were minimal. In the case of black leaf tea, differences were observed, amounting to 1.23 mg/L in the extreme case. When comparing the obtained results of aluminum content in infusions with the addition of juices and citric acid solutions with the same titratable acidity, statistically significant differences were observed only in 3 cases out of 15. This was in the case of white tea with quince juice and black tea in the case of Japanese quince juice. Therefore, the main factor influencing the increase in the aluminum content in tea infusions with additives is the lowering of the pH value, and other ingredients present in the juices do not have a significant impact. The reason for the increased aluminum content in infusions with a lowered pH may be the formation of aluminum citrate, a compound that dissolves easily in such an environment [44]. An increase in the aluminum content in infusions after the addition of lemon juice has also been described in the literature; however, due to the different conditions used in the related studies, the volume of the addition, its acidity, the stage of addition, it is impossible to draw detailed conclusions [20,21,26,42].

3.3. Assessment of the Health Risks Associated with the Consumption of Aluminum from Tea Infusions

The non-carcinogenic risk of exposure to aluminum from tea infusions was assessed using the THQ hazard quotient, the values of which were calculated for various population groups divided by age and sex and are presented in

Table 5. Values of the THQ parameter for various population groups.

		Kids			Girls			Boys			Women				Men
Age (years)		3	6	9	12	15	18	12	15	18	81	81	81	81	74	74	74	74
Average body weight (kg)		12	19	27	38	51	56	38	54	67	45	55	65	75	55	65	75	85
white tea	infusions without additives	0.59	0.48	0.37	0.29	0.22	0.20	0.32	0.25	0.21	0.25	0.21	0.18	0.15	0.26	0.22	0.19	0.17
black granulated tea		1.65	1.33	1.03	0.79	0.60	0.56	0.87	0.69	0.59	0.70	0.58	0.49	0.42	0.72	0.61	0.53	0.47
black leaf tea		0.81	0.65	0.50	0.39	0.30	0.28	0.43	0.34	0.29	0.34	0.28	0.24	0.21	0.35	0.30	0.26	0.23
pu-erh		0.27	0.22	0.17	0.13	0.10	0.09	0.15	0.11	0.10	0.12	0.10	0.08	0.07	0.12	0.10	0.09	0.08
green tea		1.46	1.18	0.91	0.70	0.53	0.50	0.77	0.61	0.52	0.62	0.51	0.43	0.37	0.64	0.54	0.47	0.41
white tea	infusions with the quince juice	0.84	0.68	0.52	0.40	0.31	0.29	0.44	0.35	0.30	0.36	0.29	0.25	0.21	0.36	0.31	0.27	0.24
black granulated tea		1.76	1.43	1.10	0.85	0.65	0.60	0.94	0.74	0.63	0.75	0.62	0.52	0.45	0.77	0.65	0.56	0.50
black leaf tea		0.87	0.70	0.54	0.42	0.32	0.30	0.46	0.36	0.31	0.37	0.30	0.26	0.22	0.38	0.32	0.28	0.24
pu-erh		0.32	0.26	0.20	0.15	0.12	0.11	0.17	0.13	0.11	0.14	0.11	0.09	0.08	0.14	0.12	0.10	0.09
green tea		1.80	1.46	1.12	0.86	0.66	0.62	0.95	0.75	0.64	0.77	0.63	0.53	0.46	0.79	0.66	0.58	0.51
white tea	infusions with citric acid solution (quince)	1.01	0.82	0.63	0.49	0.37	0.35	0.54	0.42	0.36	0.43	0.35	0.30	0.26	0.44	0.37	0.32	0.29
black granulated tea		1.67	1.35	1.04	0.80	0.61	0.57	0.89	0.70	0.60	0.71	0.58	0.49	0.43	0.73	0.62	0.54	0.47
black leaf tea		0.87	0.70	0.54	0.42	0.32	0.30	0.46	0.36	0.31	0.37	0.30	0.26	0.22	0.38	0.32	0.28	0.25
pu-erh		0.34	0.27	0.21	0.16	0.12	0.12	0.18	0.14	0.12	0.15	0.12	0.10	0.09	0.15	0.13	0.11	0.10
green tea		1.74	1.41	1.08	0.84	0.64	0.60	0.92	0.73	0.62	0.74	0.61	0.51	0.45	0.76	0.64	0.56	0.49
white tea	infusions with lemon juice	1.13	0.91	0.70	0.54	0.41	0.39	0.60	0.47	0.40	0.48	0.39	0.33	0.29	0.49	0.42	0.36	0.32
black granulated tea		2.31	1.86	1.43	1.11	0.85	0.79	1.22	0.96	0.83	0.98	0.80	0.68	0.59	1.01	0.85	0.74	0.65
black leaf tea		1.41	1.14	0.88	0.68	0.52	0.48	0.75	0.59	0.50	0.60	0.49	0.42	0.36	0.61	0.52	0.45	0.40
pu-erh		0.68	0.55	0.43	0.33	0.25	0.23	0.36	0.29	0.24	0.29	0.24	0.20	0.17	0.30	0.25	0.22	0.19
green tea		2.60	2.10	1.62	1.25	0.95	0.89	1.38	1.09	0.93	1.11	0.91	0.77	0.67	1.13	0.96	0.83	0.73
white tea	infusions with citric acid solution (lemon)	1.16	0.94	0.72	0.56	0.43	0.40	0.62	0.48	0.42	0.49	0.40	0.34	0.30	0.51	0.43	0.37	0.33
black granulated tea		2.34	1.89	1.46	1.12	0.86	0.80	1.24	0.98	0.84	1.00	0.82	0.69	0.60	1.02	0.86	0.75	0.66
black leaf tea		1.43	1.16	0.89	0.69	0.52	0.49	0.76	0.60	0.51	0.61	0.50	0.42	0.37	0.62	0.53	0.46	0.40
pu-erh		0.69	0.55	0.43	0.33	0.25	0.24	0.36	0.29	0.25	0.29	0.24	0.20	0.18	0.30	0.25	0.22	0.19
green tea		2.53	2.04	1.57	1.21	0.93	0.87	1.34	1.06	0.91	1.08	0.88	0.75	0.65	1.10	0.93	0.81	0.71
white tea	infusions with Japanese quince juice	1.15	0.93	0.72	0.55	0.42	0.39	0.61	0.48	0.41	0.49	0.40	0.34	0.29	0.50	0.42	0.37	0.32
black granulated tea		2.28	1.84	1.42	1.09	0.84	0.78	1.21	0.95	0.82	0.97	0.80	0.67	0.58	0.99	0.84	0.73	0.64
black leaf tea		1.26	1.02	0.79	0.61	0.46	0.43	0.67	0.53	0.45	0.54	0.44	0.37	0.32	0.55	0.47	0.40	0.36
pu-erh		0.62	0.50	0.39	0.30	0.23	0.21	0.33	0.26	0.22	0.26	0.22	0.18	0.16	0.27	0.23	0.20	0.17
green tea		2.56	2.07	1.59	1.23	0.94	0.88	1.36	1.07	0.92	1.09	0.89	0.76	0.66	1.12	0.95	0.82	0.72
white tea	infusions with citric acid solution (Japanese quince)	1.19	0.97	0.74	0.57	0.44	0.41	0.63	0.50	0.43	0.51	0.42	0.35	0.31	0.52	0.44	0.38	0.34
black granulated tea		2.64	2.13	1.64	1.27	0.97	0.90	1.40	1.10	0.94	1.12	0.92	0.78	0.67	1.15	0.97	0.84	0.74
black leaf tea		1.12	0.90	0.70	0.54	0.41	0.38	0.59	0.47	0.40	0.48	0.39	0.33	0.29	0.49	0.41	0.36	0.32
pu-erh		0.67	0.54	0.41	0.32	0.24	0.23	0.35	0.28	0.24	0.28	0.23	0.20	0.17	0.29	0.25	0.21	0.19
green tea		2.67	2.16	1.66	1.28	0.98	0.92	1.42	1.12	0.96	1.14	0.93	0.79	0.68	1.17	0.99	0.85	0.75

. This parameter was determined for each tea sample separately, which gave a total of 595 possible cases. In 14.5% of all analyzed cases, this parameter exceeded the value of 1, indicating the likelihood of adverse health effects. When analyzing individual types of tea, it should be noted that in the case of pu-erh tea, the THQ parameter was less than 1 in all analyzed cases. In the case of green tea, this parameter was greater than 1 in 33.6% of cases and in the case of white tea in 4.2%. Regarding the frequency of exceeding the THQ value above 1, black teas can be ranked as follows: granulated black tea 28.6% and loose leaf 5.9%. The THQ parameter was greater than 1 mainly in the group of kids aged 3 to 9 years. Analyzing the type of addition to the tea infusion, it was shown that in 20% of cases, the THQ parameter was greater than 1 in the case of both lemon juice and Japanese quince, along with the corresponding citric acid solutions. In the case of quince juice and citric acid with the same titratable acidity, this share was only 7.6%. Based on the presented results, it can be concluded that the consumption of aluminum from infusions of granulated black and green tea with the addition of lemon juice and Japanese quince is characterized by a much higher health risk compared to other groups of teas with the addition of quince juice.

Calculating the share of tea infusion as a source of aluminum in the diet is not easy because there are difficulties in determining the bioavailability of this metal [45]. The bioavailability of aluminum depends on the form in which this element occurs; therefore, in addition to the quantitative determination of aluminum, it is also essential to determine the form in which this element is found [46]. The toxicity of aluminum to living organisms depends on the speciation in which it occurs. Biological toxicology has determined that inorganic forms of aluminum (Al³⁺, Al(OH)²⁺, and Al(OH)²⁺) are the most harmful. Aluminum fluoride (Al-F) and aluminum in organic combinations (Al-org.) are much less toxic [47]. It is estimated that the average daily intake of this metal in most countries is several milligrams. Due to its toxicity, it is essential to determine the concentration, speciation, and bioavailability of aluminum in tea extracts and to determine their modifications resulting from changes in brewing conditions. Generally, despite the high aluminum concentration in tea, its absorption in the gastrointestinal tract is low. It has been determined that only 0.1% of aluminum consumed from various sources during the day is absorbed (depending on the form in which this metal is found). If the aluminum forms found in tea are more bioavailable than those found in other dietary ingredients, then this beverage could contribute more to the daily intake of aluminum than the total amount in other foods [43]. Research shows that the primary forms of aluminum in the infusion are complexes of this metal with polyphenols, aluminum fluoride, aluminum oxalate, free Al^3+, and its hydrolysates. It is worth noting that it is very difficult to determine a consistent picture of aluminum speciation in tea infusions [47]. Despite the high aluminum concentration in the tea infusion, the fact that it forms strong complexes reduces its toxicity [48]. The influence of factors such as infusion time, sugar addition, and lemon juice addition on aluminum speciation in the infusion was examined. It turns out that the extension of the extraction time and the addition of sugar do not significantly change the speciation of this metal. However, adding lemon juice to previously brewed tea modifies the form of aluminum in both black and green tea infusions. The results of this study indicate that the addition of lemon juice has a significant effect on aluminum speciation in tea infusions. The increase in the solubility of aluminum ions caused by the increase in the acidity of infusions and the change in the form of this element in the infusion increase its absorption by the body [12,39].

4. Conclusions

So far, no studies have been carried out to determine the effect of the aluminum content in infusions with the addition of juices other than lemon juice. However, due to consumers’ growing awareness regarding the health-promoting and anti-nutritional ingredients of the food consumed, the impact of adding lemon, Japanese quince, and quince juices to tea infusions was determined in this study. The significant difference in the titratable acidity of the juices contributed to a significant difference in the pH of the final infusions, which resulted in a substantial increase in the aluminum content in the infusions with the addition of lemon juice and Japanese quince. It has been shown that the main factor influencing the increase in the aluminum content in tea infusions with additives is the lowering of the pH value; therefore, due to its low titratable acidity, quince juice can be recommended as an addition to tea infusions. Additionally, it should be added to the infusion after removing the tea leaves to reduce the aluminum content. Estimated daily exposure to aluminum in the general population, assessed in several European countries, ranged on average from 0.2 to 1.5 mg/kg bw/week, and this figure increased to 2.3 mg/kg bw/week in highly exposed individuals [31]. The TWI set at 1 mg/kg body weight/week may be exceeded in a significant part of the European population, especially in people consuming granulated black tea and green tea with pH-lowering additives. It seems necessary for tea producers to add information on aluminum content to tea packaging and increase public awareness of the risks associated with excessive aluminum consumption, especially by small children, who are particularly vulnerable to exceeding the tolerable weekly intake.