Determination of Mineral Elements in Milk Products by Inductively Coupled Plasma-Optical Emission Spectrometry

Tunisian Silybum Species: Important Sources of Polyphenols, Organic Acids, Minerals, and Proteins across Various Plant Organs

Silybum marianum and Silybum eburneum are wild edible Mediterranean plants used in the human diet. This study presents the initial findings on the phytochemical characterization of Tunisian S. marianum and S. eburneum organs. It examined their mineral, sugar, organic acid, polyphenolic, and seed storage protein contents, as well as their antioxidant potential. In S. marianum, stems had high sodium and potassium contents, while the immature and mature seeds were rich in calcium and magnesium. However, S. eburneum had high potassium levels in stems and high sodium and calcium levels in the flowers. S. marianum showed substantial fructose variation among its organs. Conversely, S. eburneum exhibited significant heterogeneity in glucose, sucrose, and maltose levels across its organs, with maltose exclusively detected in the immature seeds. A notable organ-dependent distribution of organic acids was observed among the two species. Higher levels of phenolic contents were detected in both mature and immature seeds in both species compared to the other plant parts. The seeds possessed higher antioxidant activities than other plant organs. In both S. marianum and S. eburneum seeds, albumins and globulins were the predominant protein fractions. This study brings evidence supporting the important potential of Silybum organs as sources of nutrients with antioxidant properties for producing functional food.

The Biochemical, Microbiological, Antioxidant and Sensory Characterization of Fermented Skimmed Milk Drinks Supplemented with Probiotics Lacticaseibacillus casei and Lacticaseibacillus rhamnosus

A variety of foods fermented with lactic acid bacteria (LAB) serve as dietary staples in many countries. The incorporation of health-promoting probiotics into fermented milk products can have profound effects on human health. Considering the health benefits of Yakult, the current study was undertaken to develop an enriched Yakult-like fermented skimmed milk drink by the addition of two probiotic strains, namely Lacticaseibacillus casei (Lc) and Lacticaseibacillus rhamnosus (Lr). The prepared drinks were compared in terms of various parameters, including their physicochemical properties, proximate chemical composition, mineral estimation, microbial viable count, antioxidant activity, and sensory evaluation. Each strain was employed at five different concentrations, including 1% (T1), 1.5% (T2), 2% (T3), 2.5% (T4), and 3% (T5). The prepared Yakult samples were stored at 4 °C and analyzed on days 0, 7, 14, 21, and 28 to evaluate biochemical changes. The findings revealed that the concentration of the starter culture had a significant (p ≤ 0.05) impact on the pH value and moisture and protein contents, but had no marked impact on the fat or ash content of the developed product. With the Lc strain, Yakult's moisture content ranged from 84.25 ± 0.09 to 85.65 ± 0.13%, whereas with the Lr strain, it was from 84.24 ± 0.08 to 88.75 ± 0.13%. Protein levels reached their highest values with T5 (3% concentration). The acidity of all treatments increased significantly due to fermentation and, subsequently, pH showed a downward trend (p ≤ 0.05). The total soluble solids (TSS) content decreased during storage with Lc as compared to Lr, but the presence of carbohydrates had no appreciable impact. The drink with Lc exhibited a more uniform texture and smaller pore size than Yakult with Lr. Except for the iron values, which showed an increasing trend, the contents of other minerals decreased in increasing order of the added probiotic concentration used: 1% (T1), 1.5% (T2), 2% (T3), 2.5% (T4), and 3% (T5). The highest lactobacilli viable count of 8.69 ± 0.43 colony-forming units (CFU)/mL was observed with the T1 Lr-containing drink at the end of the storage period. Regarding the storage stability of the drink, the highest value for DPPH (88.75 ± 0.13%) was found with the T1 Lc drink on day 15, while the highest values for FRAP (4.86 ± 2.80 mmol Fe2+/L), TPC (5.97 ± 0.29 mg GAE/mL), and TFC (3.59 ± 0.17 mg GAE/mL) were found with the T5 Lr drink on day 28 of storage. However, the maximum value for ABTS (3.59 ± 0.17%) was noted with the T5 Lr drink on the first day of storage. The results of this study prove that Lc and Lr can be used in dairy-based fermented products and stored at refrigerated temperatures.

Mineral Composition in Delactosed Dairy Products: Quality and Safety Status

Mineral elements are ingested through the diet (Li, Be, B, Na, Mg, Al, K, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Ag, Cd, Sb, Ba, Tl, Pb, and Bi). Essential minerals have structural, biochemical, nutritional and catalytic functions; therefore, they are fundamental for human health. In this research, thirty commercial delactosed dairy products from different varieties were supplied by various markets in Sicily (Italy), and their mineral contents were determined by using inductively coupled plasma mass spectrometry (ICP-MS) with the following aims: (1) to highlight the differences among various products; (2) to evaluate if it is possibly related to the analyzed samples of their product group; (3) to evaluate the nutritional quality and safety related to intake of these dairy products. Evident differences were found among the samples depending on the type of product. A good separation between mozzarella-on the one hand-and crescenza and primo sale-on the other-was observed. The mozzarella samples were distinguished by the higher Fe, V and Co contents, and the lower amount of Al. Based on shares of the RDA, the analyzed dairy samples are a good source of Ca (up to 58% of the nutrient reference values), with a relatively high concentration of Na (between 5.5% and 22%). Any safety risk for consumers due to exposures to toxic elements through analyzed samples is excluded. The obtained results give reason to expect further insight concerning the direct comparison between the delactosed and non-delactosed product, in order to evaluate if the manufacturing process can affect the content of some mineral.

Calcium: A comprehensive review on quantification, interaction with milk proteins and implications for processing of dairy products

Calcium (Ca) is a key micronutrient of high relevance for human nutrition that also influences the texture and taste of dairy products and their processability. In bovine milk, Ca is presented in several speciation forms, such as complexed with other milk components or free as ionic calcium while being distributed between colloidal and serum phases of milk. Partitioning of Ca between these phases is highly dynamic and influenced by factors, such as temperature, ionic strength, pH, and milk composition. Processing steps used during the manufacture of dairy products, such as preconditioning, concentration, acidification, salting, cooling, and heating, all contribute to modify Ca speciation and partition, thereby influencing product functionality, product yield, and fouling of equipment. This review aims to provide a comprehensive understanding of the influence of Ca partition on dairy products properties to support the development of kinetics models to reduce product losses and develop added-value products with improved functionality. To achieve this objective, approaches to separate milk phases, analytical approaches to determine Ca partition and speciation, the role of Ca on protein-protein interactions, and their influence on processing of dairy products are discussed.

Determination of Trace and Major Elements in Vegan Milk and Oils by ICP-OES After Microwave Digestion

Increasing technological developments also bring about environmental pollution. Heavy metals and metallic compounds, as a result of soil, water, and air industrialization, pass through to people and animals through the food chain and have a negative impact on health. In this study, the concentrations of Na, Mg, K, Ca, P, Fe, Cu, B, Mn, Zn, Al, S, As, Bi, Cd, Co, Cr, Mo, Ni, Pb, Pt, Sb, Se, Sn, Ti, W, and Hg in commercial vegan milk (soybean milk, coconut milk, and almond milk) and oils (soybean oil, coconut oil, bitter almond oil, sweet almond oil, and walnut oil) were determinated using inductively coupled plasma-optical emission spectrometry after microwave digestion. In order to compare the efficiencies of digestion in vegan milk and oil samples, 6 mL of HNO₃ (conc.), 3 mL of H₂O₂ (30%); 7 mL of HNO₃ (conc.), 3.5 mL of H₂O₂ (30%), and 8 mL of HNO₃ (conc.), 4 mL of H₂O₂ (30%) were used in microwave digestion procedures. The proposed procedures were applied to the analysis of 81 vegan milk and 125 vegan oil samples covering three different brands in Turkey. Na, Mg, K, Ca, P, S, Mn, Zn, Cu, B, Sb, and Sn concentrations in vegan milks ranged (minimum-maximum in ppm) as follows: 307.4-501.2, 1.8-15.6, 478.8-1300.4, 276.3-1189, 197-797.8, 18.7-241.4, 0.09-0.42, 0-0.58, 0.02-1.06, 0.34-1.56, 0.26-0.67, and 3.4-30.4 ppm, respectively. The results of Na, K, Ca, P, Mg, S, Mn, Zn, Se, Fe, Cu, Sb, and Sn concentrations in vegan oils (minimum-maximum in ppm) ranged as follows: 6.8-31.2, 403.5-425.2, 142.8-160.4, 71.65-149.8, 0.35-0.85, 14.2-35.2, 0.02-0.27, 0.07-0.36, 1.90-4.64, 0.92-5.36, 0.01-0.05, 1.02-1.66, and 21.2, 35.0 ppm, respectively. Vegan milk contents except for Se, Fe, Sb, and Sn in this study were higher than vegan oil contents. The methods were validated by linearity, limits of detection and quantification, precision, and analyzing certified reference material (NIST SRM-3235), soybean milk. The highest values of LOD were found Pb, P, and Bi, and the highest values of LOQ were found Mo, Pb, and Sb.

Determination of some element levels in various kinds of cow's milk processed in different ways

This study aimed to measure zinc (Zn), selenium (Se), copper (Cu), iron (Fe), chromium (Cr), nickel (Ni), lead (Pb), cadmium (Cd), arsenic (As), and aluminum (Al) in whole, semi-skimmed, skimmed, organic, fruit-flavored (strawberry, banana, and cocoa), pasteurized, and raw cows' milk. The samples were collected from sterilized and pasteurized milk processed in different ways in Ankara; the milk was kept in refrigerated raw milk storage tanks on dairy farms. Ninety samples were collected, and there were ten samples in each group. Analyses were performed using inductively coupled plasma-mass spectrometry. Lead and Cd were not found in any samples, while Zn was observed in all samples. The element with the highest frequency of occurrence was Zn, followed by Cr = As> Al > Se > Fe > Ni > Cu > Pb = Cd, in decreasing order. The lowest concentration among the essential elements was seen in Cu. Aluminum and As were found in 85% and 94.45% of the samples, respectively. However, the present concentrations were below the level of a probable negative effect. It was found that the concentrations of elements in milk showed statistically significant differences, depending on the milk type. It is recommended that low-quality materials not be used in the preparation of milk; the element concentrations in milk and the feed and water consumed by animals should be controlled regularly, and the animals should not be pastured near industrial and traffic sites to protect public health.

Rapid determination of majority cations in yoghurts using on-line connection of capillary electrophoresis with mini-dialysis

An analyser was constructed on the basis of on-line connection of capillary electrophoresis over a short separation path with continuous mini-dialysis sample collection. The developed instrument was employed for simultaneous determination of the majority minerals K⁺, Ca²⁺, Na⁺ and Mg²⁺ (and possibly NH₄⁺ ions) in commercially available unflavoured yoghurts. The cations are released from the organic structures by digestion with boiling 6 mol/L HCl. They were separated from residues of the organic matrix by a dialysis probe and were transferred to a stream of water. From the continuous stream, the dialysate was injected into the separation capillary through a flow-gating interface. Within the reliability interval, the determined total mineral content was equal to their contents stated on the yoghurt labels and the content determined by flame atomic absorption spectrometry and complexometric titration. The relative standard deviation of the electrophoretic determination is mostly about 5%.

Development of Infrared Prediction Models for Diffusible and Micellar Minerals in Bovine Milk

Simple Summary

Minerals are distributed in milk in two main forms: The diffusible (or soluble) fraction, composed of free ions and inorganic salts, and the micellar fraction, composed of mineral elements located on the surface or in the inner part of casein micelles. The ratio between diffusible and micellar minerals strongly affects milk coagulation ability. The objective of this study was to investigate the ability of mid-infrared spectroscopy to predict diffusible and micellar Ca, P, K, Mg and Na in individual milk samples of Holstein Friesian cows. Overall, the accuracy of mid-infrared prediction models was moderate for Ca, P and Mg, and low for micellar K, micellar Na and diffusible Na.

Abstract

Milk and dairy products are major sources of minerals in human diet. Minerals influence milk technological properties; in particular, micellar and diffusible minerals differentially influence rennet clotting time, curd firmness and curd formation rate. The aim of the present study was to investigate the ability of mid-infrared spectroscopy to predict the content of micellar and diffusible mineral fractions in bovine milk. Spectra of reference milk samples (n = 93) were collected using Milkoscan™ 7 (Foss Electric A/S, Hillerød, Denmark) and total, diffusible and micellar content of minerals were quantified using inductively coupled plasma optical emission spectrometry. Backward interval partial least squares algorithm was applied to exclude uninformative spectral regions and build prediction models for total, diffusible and micellar minerals content. Results showed that backward interval partial least squares analysis improved the predictive ability of the models for the studied traits compared with traditional partial least squares approach. Overall, the predictive ability of mid-infrared prediction models was moderate to low, with a ratio of performance to deviation in cross-validation that ranged from 1.15 for micellar K to 2.73 for total P.

Yogurt and whey beverages available in Brazilian market: Mineral and trace contents, daily intake and statistical differentiation

Mineral and trace elements (Ca, Fe, K, Mg, Na, Pb, Cd, Cr, Cu, and Mn) in commercial strawberry-flavored yogurts and fermented whey beverages in Brazil were investigated. K, Ca, Na, Mg and Fe concentrations ranged from 1.6 to 1.4, 1.4 to 1.1, 0.74 to 0.68, 0.16 to 0.11, and 0.01 mg g-¹ for yogurts and whey beverages, respectively. Similar concentrations of the minerals were observed for both products, except Mg (0.16 mg g-¹ in yogurts and 0.11 mg g-¹ in whey beverages). Cd, Cr, Cu, Mn, and Pb was found below the detection limit (21.4 to 94.1 μg g^-1), demonstrating safety levels for consumption. Regarding the mineral daily intake, consumption of 100 g of the product has relevance for calcium in infants (>40%) and children between 4 and 8 years (>13%), and a greater contribution of yogurt over whey beverage was observed. PLSDA model suggested that Mg analytical determination should be performed to ensure the identity of the product.

Determination of macro, micro and trace elements in citrus fruits by inductively coupled plasma-optical emission spectrometry (ICP-OES), ICP-mass spectrometry and direct mercury analyzer

BACKGROUND

Citrus fruits are widely consumed around the world. Several elements are known to have important physiological functions in living things, whereas others are reported to have toxic effects. This study was aimed to analyze the concentration of macro, micro and trace elements in citrus fruit varieties. Samples were acid digested using a microwave system and analyzed for macro elements by inductively coupled plasma-optical emission spectrometry (ICP-OES) and for micro and trace elements by inductively coupled plasma-mass spectrometry (ICP-MS). The application of analytical techniques was analyzed by determining method validation parameters including limits of detection and quantification, linearity, precision, spiking experiments and analyzing certified reference material (NIST CRM-1570a), Spinach leaves.

RESULTS

The elemental levels of citrus fruits were found largely to be dependent upon the type of analyzed samples. Among nutritionally important elements, citrus fruits were good sources of potassium (95.13-270.4 mg kg^-1 ), calcium (10.57-75.29 mg kg^-1 ), zinc (466.5-1611 µg kg^-1 ) and manganese (35.35-1902 µg kg^-1 ). The concentrations of toxic elements (Pb, Cd, As, Al, Hg) were very low.

CONCLUSION

In general, the concentrations of analyzed elements were within the critical levels specified by the Food and Agriculture Organization/World Health Organization and Food and Nutrition Board USA. Linear discriminant analysis successfully separated the samples into clear groups with 93.9% correct classification. © 2018 Society of Chemical Industry.

Selective sensing of submicromolar iron(III) with 3,3',5,5'-tetramethylbenzidine as a chromogenic probe

The development of highly selective and sensitive method for iron(III) detection is of great importance both from human health as well as environmental point of view. We herein reported a simple, selective and sensitive colorimetric method for the detection of Fe(III) at submicromolar level with 3,3,'5,5'-tetramethylbenzidine (TMB) as a chromogenic probe. It was observed that Fe(III) could directly oxidize TMB to form a blue solution without adding any extra oxidants. The reaction has a stoichiometric ratio of 1:1 (Fe(III)/TMB) as determined by a molar ratio method. The resultant color change can be perceived by the naked eye or monitored the absorbance change at 652 nm. The method allowed the measurement of Fe(III) in the range 1.0×10(-7)-1.5×10(-4) mol L(-1) with a detection limit of 5.5×10(-8) mol L(-1). The relative standard deviation was 0.9% for eleven replicate measurements of 2.5×10(-5) mol L(-1) Fe(III) solution. The chemistry showed high selectivity for Fe(III) in contrast to other common cation ions. The practically of the method was evaluated by the determination of Fe in milk samples; good consistency was obtained between the results of this method and atomic absorption spectrophotometry as indicated by statistical analysis.