Importance of using tomato serum in the development of functional food products
Authors: Irina Zharkova , Danil Ivanchikov , Inessa Plotnikova , Gayane Martirosyan 
Published: November 2024

Background: The significance of incorporating tomatoes in the development of functional food products is due to their content of vitamins, carotenoids, and minerals. In industrial tomato processing, a considerable amount of tomato serum (clarified tomato juice) is produced. For instance, during tomato paste production, serum constitutes 80% of the total volume of processed tomatoes. Tomato serum contains essential organic, phenolic, and polyphenolic compounds, water-soluble vitamins, macro- and microelements. One promising application is the use of tomato serum in yeast bread technology. A specific application is using it as a growth stimulator for baker’s yeast, as well as for microorganisms in sourdoughs, including Type 1 and wheat-based sourdough. This is an effective method to enhance the biotechnological characteristics of sourdoughs, as well as the organoleptic and physico-chemical quality indicators of bakery products, including enriched and functional products. The aim of the study is to investigate the mineral composition of tomato serum from red-fruited, yellow-fruited, and dark-hued tomatoes, as well as flour from various industrial producers of premium-grade baking wheat flour, for their potential combined use in the production of enriched and functional bakery products.
Objective: Tomato serum was obtained under laboratory conditions by centrifuging pre-crushed and thermally processed fruits of the red-fruited variety "Sibirskiy Skorospeliy," yellow-fruited variety "Zolotoye Runo" and dark-hued variety "Chernyy Aysberg." The tomatoes were grown in 2023 in open fields in the village of Nikonovo, Voronezh Voronezh region, Russian Federation. The mineral composition of tomato serum from various tomato varieties and premium-grade wheat flour from different industrial producers (JSC "Mukomolny Kombinat 'Voronezhskiy'", JSC "Makfa", and LLC "Chernyy Khleb", Russia) was investigated. 
Methods: The mineral content was determined using inductively coupled plasma mass spectrometry with a quadrupole mass spectrometer, Nexion 300 D. The basic physicochemical quality indicators of the high-grade wheat flour were rapidly assessed using the "Chopin Technologies Infraneo chopin" device.
Results: The dry matter content in tomato serum ranges from 4.8% to 6.1%. All tomato serum samples exhibited an acidic reaction: the "Sibirskiy Skorospeliy" variety was the most acidic at pH 3.90, "Chernyy Aysberg" had a pH of 3.99, and "Zolotoye Runo" was the least acidic at pH 4.37. The content of 24 mineral elements was determined in both tomato serum and premium-grade wheat flour. Tomato serum from various tomato varieties contains a broad range of minerals. Potassium is the most abundant (2,755.5-3,274.5 mg/kg), with its content being 1.3-2.1 times higher than in premium-grade wheat flour. Significant amounts of phosphorus (275.8-279.0 mg/kg), magnesium (116.3-146.4 mg/kg), and calcium (63.88-91.61 mg/kg) are also present in the serum. Iron content varies from 2.533 mg/kg (variety "Chernyy Aysberg") to 17.630 mg/kg (variety "Sibirskiy Skorospeliy"). In premium-grade wheat flour from JSC "Mukomolny Kombinat 'Voronezhskiy'" and JSC "Makfa", iron content is 9.109-9.643 mg/kg, while in the sample from LLC "Chernyy Khleb," it is 2.29-2.43 times higher. Zinc content in tomato serum and industrial wheat flour ranges from 1.921-2.685 mg/kg and 8.12-9.429 mg/kg, respectively. Consuming 100 g of tomato serum can meet 7.9-9.4% of the daily potassium requirement, 2.8-3.5% of magnesium, 4.7-9.8% of iron, and 3.9-4.0% of phosphorus. Sodium content in tomato serum is minimal, ranging from 23.74 to 68.11 mg/kg, which is 0.2-0.5% of the daily requirement for an adult.
Conclusion: Incorporating tomato serum into food products, including bakery goods, can enrich their composition with deficient macro- and microelements and improve the bioavailability of minerals in flour. A specific application of tomato serum could be as a growth stimulator for wheat sourdough microorganisms (including type 1, I), which is an effective way to enhance the biotechnological properties of baker’s sourdoughs, thereby improving their functionality and the organoleptic and physico-chemical quality of bakery products.
Keywords: tomato serum, clarified tomato juice, wheat flour, micro- and macro-element composition, functional properties.