Development, characterization and storage stability of antioxidant rich beetroot pomace based jam

Introduction

In recent years, the food industry has witnessed a growing interest in utilizing agricultural byproducts to create value-added products, thereby reducing waste and promoting sustainability. Beetroot pomace, a by-product generated during the processing of beetroot into juice or slices, has garnered attention due to its rich nutritional composition and potential health benefits. This fibrous material, often overlooked and underutilized, contains significant amounts of dietary fiber, antioxidants, and bioactive compounds such as betalains. Betalains, specifically betacyanins and betaxanthins found in beetroot, have demonstrated antioxidant, antiinflammatory, and potentially anticancer properties in various studies (Manohar and Divakar, 2020; Smith et al., 2020) [9,16] . The concept of incorporating beetroot pomace into jams is particularly intriguing as jams are popular globally and consumed by a wide demographic, offering a convenient vehicle for delivering bioactive compounds to consumers. The utilization of beetroot pomace in jam production not only addresses environmental concerns by reducing waste but also enhances the nutritional profile of the final product. In market different type of jams are available but they are loaded with artificial colours, sugar and preservatives but by utilizing the beetroot pomace for jam production it provide natural colour and also the antioxidants although it is still loaded with sugar but beside this it provide antioxidants and also look tempting to consume. Furthermore, it presents an opportunity to develop innovative food products that cater to health-conscious consumers seeking functional foods. Despite these potential benefits, research exploring the feasibility, sensory attributes, and consumer acceptance of beetroot pomace-based jams remains limited. This paper aims to review existing literature on the nutritional composition of beetroot pomace, the extraction methods of bioactive compounds, and the technological aspects involved in incorporating beetroot pomace into jams. Additionally, it will discuss the sensory characteristics, shelf-life of beetroot pomace-based jams. By addressing these aspects, this research contributes to expanding the knowledge base on sustainable food processing practices and exploring new avenues for utilizingagricultural by-products in functional food applications.

Material and Methods

Procurement, recovery and processing of beetroot Fresh and fully mature 1 kg beetroot sourced from the local market in Palampur underwent initial cleaning to eliminate dust and extraneous matter, followed by removal of the calyx and peel. The peeled and sliced beetroot was processed using a Morphy Richard Maximo Juice Mixer Grinder to obtain pomace. Subsequently, the extracted pomace was squeezed through muslin cloth to separate the juice component.

Development of jam

The jams were prepared by bending extacted beetroot pomace with papaya pulp in different ratio and has been presented below:

Sensory evaluation

A panel of 10 semi-trained judges evaluated beetroot pomaceenriched jams alongside control samples using a nine-point hedonic scale (Ranganna, 2020) [13] to assess colour, appearance, texture, flavor, taste, and overall acceptability. Control samples followed standardized recipes, while supplemented samples included beetroot pomace.

Nutritional analysis

The moisture, crude fat, crude protein, crude fiber, total ash content and total carbohydrates were analyzed following AOAC (2010) standard methods for proximate constituents. Ascorbic acid content done by Ranganna (2007) [12] method. Total phenols and flavanoids content were determinder by (Singleton et al. 1999) [15] and (Zhishen et al. 1999) [20] method. Total antioxidant activity by (Brand Williams et al. 1995) and by ABTS Radical Scavenging Assay (Re et al. 1999) [14] method. Total Betalain content was determined using (Stintzing et al. 2003) [17] method. The colour properties of the samples were assessed by measuring their L\, a\, and b\* values using a Colour Flex meter with 45°/0° geometry, and standard illuminant C (Hunter Lab Colour Flex 150 by Hunter Associates Inc., USA).

Shelf-life stability and quality evaluation of stored jam

The developed beetroot pomace based jam was stored in glass jars at refrigerated temperature. Jam was analyzed fresh and after 30, 60 and 90 days of storage. The product was evaluated organoleptically by 10 panelists using nine-point hedonic rating scale. The developed product was nutritionally evaluated with respect to moisture, crude protein, crude fiber, total betalain content and antioxidant activity.

Statistical analysis

To analyze the data, OPSTAT software was employed. The mean and standard deviation for various characteristics of whole beetroot was computed. An independent sample t-test was conducted to compare nutritional, functional, and antioxidant characteristics between developed jam and their respective control samples. In the case of storage and sensory analysis, a one-way ANOVA test was used and compared at 5 percent level of significance to detect any notable variations in sensory attributes and nutritional characteristics of stored products during a 90-day storage period.

Result and Discussion

Recovery of peel, juice, pomace and pomace powder Data pertaining to the recovery of peel, juice and fresh pomace is given in Table 1. The results revealed that from one kg of whole beetroot 89.70g of peel, 415.60g of fresh pomace and 375.00 ml of juice. In the study, Kale et al. (2018) [7] has documented recovery of 91.0 percent of the beetroot which constituted of edible portion and 8.07 percent comprised waste.

Nutritional and antioxidant properties of whole beetroot

The moisture content in beetroot was determined to be 88.5±1.39 percent (Table 2), which aligns with the findings of Bunkar et al. (2020) [5] , where they recorded a moisture content of 88.00 percent in beetroot. The protein content in beetroot was found to be 1.68±0.07 percent, and this value is consistent with the results reported by Yashwant (2015) [19] and Mirmiran et al.

(2020) [10] . Beetroot contained 0.27±0.06 percent fat and 2.43±0.35 percent fiber, which closely resembles the values of 0.20 percent fat and 2.8 percent fiber documented by Bunkar et al. (2020) [5] . Additionally, the total ash content in beetroot was identified as 1.43±0.22 percent, and this figure is in line with the observations made by Kale et al. (2018) [7] . The total carbohydrate content in beetroot was 8.12±0.78 percent, which closely resembled the value (9.56%) reported by Mirmiran et al. (2020) [10] Beetroot had high moisture content (88.50%), which is typical for root vegetables, contributing to its short shelf life and need for immediate processing (Table 2). Its moderate protein (1.68%), fiber (2.43%), and ash (1.43%) content reflect its nutritional value, aligning with previous findings by Bunkar et al. (2020) [5] and Kale et al. (2018) [7] . The carbohydrate content (8.12%) makes beetroot a natural source of energy (Table 2). [4] , who reported 462-838 mg/100g across seasons. Total phenolic content was 71.96±0.55 m g GAE/100g, and flavonoid content was 41.16±1.49 mg QE/100g, closely matching Kaur et al. (2021) [8] , who reported 77.88 mg GAE/100g of phenols and 42.75 mg QE/100g of flavonoids.

Sensory evaluation of developed jams

Table 3 represents the sensory scores of jams developed by using fresh beetroot pomace and papaya pulp in varying proportions. Treatment J3 (50% beetroot pomace and 50% papaya) scored highest in appearance (7.90), color (8.00), flavor (8.20), taste (8.30), and overall acceptability (8.00) among J1, J2, J3, J4, and J5. It was selected for further analysis due to its superior sensory evaluation scores (figure 2).

Proximate composition

The proximate composition of jam in comparison to control has been represented in Table 4. The results showed that there was a slight increase in the moisture content of the supplemented jam (43.13%) than the control jam (41.76%) but this difference was non-significant. With respect to protein, the value for control jam (1.32%) was significantly increased as compared to beetroot pomace supplemented jam (1.1%), this is because beetroot pomace has a greater protein content than papaya. Akath et al. (2010) [1] reported that the protein content of papaya was 0.39 percent. The fat content of control jam and supplemented jam was found to be non-significant, because fruits and vegetables contain very low amounts of fat. Crude fiber in control jam and supplemented jam was 2.15 and 1.95 percent respectively. The crude fiber was significantly higher in control jam because beetroot pomace contains more fiber content than papaya i.e., 2.10 percent in beetroot pomace (Abdo et al. 2020) [21] and 1.52 percent in papaya (Akath et al. 2010) [1] . The ash and carbohydrate content of control jam was slightly higher than the J3 jam, but the difference was non-significant.

Antioxidant properties

Beetroot pomace contained a high concentration of antioxidants, including phenols, flavonoids, and ascorbic acid. The antioxidant properties of beetroot pomace-based jam has been expressed in Table 5. The ascorbic acid content in the supplemented jam was noted to be 1.06 mg/100g, while the control jam had a 1.20 times lower amount of ascorbic acid, observed to be 0.86 mg/100g.The higher content of ascorbic acid in the supplemented jam can be attributed to its composition, which consists of a blend of 50 percent beetroot pomace and 50 percent papaya pulp. Papaya pulp naturally contains a higher concentration of ascorbic acid compared to beetroot pomace, which is the sole component in the control jam. Consequently, the control jam exhibited a lower level of ascorbic acid content when compared with the blended jam, primarily due to the absence of the ascorbic acid-rich papaya pulp in its composition. Igual et al. (2016) [6] observed a significant disparity in the levels of ascorbic acid between jams, suggesting that the process of making jam led to the conversion of ascorbic acid to dehydro-ascorbic acid, which was more pronounced than what was seen in fresh grapefruit samples. The processing of beetroot pomace into jam resulted in an increase in both total phenol content (61.35 mg/100g) and flavonoid content (38.84 mg/100g) compared to the initial values of 59.40 mg/100g and 34.93 mg/100g, respectively. This enhancement is attributed to the concentration of the food matrix and the disruption of cell walls during the jam-making process, facilitating better extraction of phenolic compounds. However, when comparing the supplemented jam to control jam, a significant decrease in phenol and flavonoid content was observed in the supplemented jam (55.27 mg/100g and 29.42 mg/100g, respectively). This difference can be attributed to the lower phenolic and flavonoid content in papaya (35.56 mg/100g and 22.53 mg/100g, as reported by Addai et al. (2013), and the supplemented jam contained 50 percent of papaya pup in place of beetroot pomace. The ant oxidative potential of beetroot is intricately tied to its inherent bioactive compounds. While there was a noticeable increase in the overall content of total phenols and flavonoids.

The antioxidant activity assessed by both DPPH and ABTS methods also displayed an upward trend. This increase was closely related to the elevated content of these bioactive compounds. Specifically, the antioxidant activity measured by DPPH and ABTS assays was significantly higher in the control jam at 40.27 and 56.26 percent, respectively, compared to the supplemented jam, which exhibited values of 36.09 and 50.73 percent respectively. The disparity can be attributed to the inclusion of papaya in the jam, as papaya contains lower levels of phenols and flavonoids compared to beetroot pomace, resulting in a reduced antioxidant activity in the supplemented jam. The effect of processing on betalain content was observed in jam, which is represented in figure 3. As is evident from the data control jam contained significantly higher betalain (52.64 mg/100g) when compared to supplemented jam (27.22mg/100g). The betacyanin and betaxanthin content of control jam were 36.11 mg/100g and 88.76 mg/100g respectively, which were also higher than supplemented jam (11.48and 38.70 mg/100g). Oksuz et al. (2015) noted that the application of heat in the preparation of red beet jam resulted in the transformation of betalains into alternative compounds, including betanidin and its breakdown products, such as isobetanin, neobetanin, and vulgaxanthin.The betalain content experienced a reduction as a result of heat treatment, in contrast to the betalain content found in fresh beetroot pomace. However, in the case of supplemented jam, the betalain levels were reduced due to the absence of betalain pigments in papaya. Consequently, the control jam, which exclusively comprised of 100 percent beetroot pomace, displayed elevated betalain content compared to the supplemented jam, which consisted of a mixture of 50 percent beetroot pomace and 50 percent papaya pulp.

Colour analysis of jam

Table 4.21 represents the effect of processing on colour of jam and toffee. L*, a*and b* values were significantly higher in supplemented jam as compared to control. The reduced lightness value in the control jam can be attributed to its exclusive composition of beetroot pomace, which, upon cooking, initiated a Maillard reaction, resulting in a darker appearance. Kaur (2021) reported the colour value of L* at 19.54, a* at 13.14 and b* at -14.11 in beetroot jam. supplemented with date pit powder decreased over a 90 days storage periods because during storage phenolic compounds are easily oxidized and become one of the reasons for the reduction of antioxidant activity.

Conclusion

The study demonstrated the potential of beetroot pomace for value addition through the development of jam enhances the nutritional and antioxidant properties. The developed jam exhibited appreciable levels of antioxidants, phenols , flavonoid and betalain content while remaining organoleptically acceptance through out 90 days of storage. Therefore beetroot pomace based jam represents a promising functional food product for the utilization of beetroot processing by products.

References

1. Akath S, Nath A, Bidyut CD, Jai P, Patel RK, Shahida C. Studies on nutritive value of papaya (Carica papaya L.) fruits at different stages for their amenability to specific use. Tropical Agriculturist. 2010;158:15-22.
2. Anwar S, Saleem A, Razzaq A, Nasir MA, Hussain A, Tariq MR, et al. Nutritional probing and storage stability of papaya jam supplemented with date pit powder. Heliyon. 2023;9(5).
3. AOAC. Official method of analysis. 16th ed. Washington, DC: Association of official analytical chemists; 2010.
4. Bucur L, Taralunga GH, Schroder V. The betalains content and antioxidant capacity of red beet (Beta vulgaris L. subsp. vulgaris) root. Farmacia. 2016;64:198-201.
5. Bunkar DS, Anand A, Meena KK, Goyal SK, Paswan VK. Development of production technology for preparation of beetroot powder using different drying methods. Annals of Phytomedicine. 2020;9(2):293-301.
6. Igual M, Garcia-Martínez E, Camacho MM, MartínezNavarrete N. Stability of micronutrients and phytochemicals of grapefruit jam as affected by the obtention process. Food Science Technology. 2016;22:20312.
7. Kale RG, Sawate AR, Kshirsagar RB, Patil BM, Mane R. Studies on evaluation of physical and chemical composition of beetroot (Beta vulgaris L.). International Journal of Chemical Studies. 2018;6(2):2977-2979.
8. Kaur S, Kaur N, Aggarwal P, Grover K. Bioactive compounds, antioxidant activity, and colour retention of beetroot (Beta vulgaris L.) powder: Effect of steam blanching with refrigeration and storage. Journal of Food Processing and Preservation. 2021;45(3):15247.
9. Manohar PS, Divakar S. Betalains and betalain-producing bacteria: A novel platform for promoting human health. Critical Reviews in Food Science and Nutrition. 2020;60(3):487-505.
10. Mirmiran P, Hushilsat Z, Gaeini Z, Bahadoran Z, Azizi F. Functional properties of beetroot (beta vulgaris) in management of cardio-metabolic diseases. Journal of Nutrition. 2020;17:1-15.
11. Oksuz T, Surek E, Tacer-Caba Z, Nilufer-Erdil D. Phenolic contents and antioxidant activities of persimmon and red beet jams produced by sucrose impregnation. Food Science Technology. 2015;3:1-8.
12. Ranganna S. Handbook of analysis and quality control for fruit and vegetable products. New Delhi: McGraw Hill Publishing Company Limited; 2007.
13. Ranganna S. Handbook of Analysis and Quality Control for Fruit and Vegetable Products. 2nd ed. New Delhi, India: Tata McGraw-Hill; 2020.
14. Re R, Pellegrini N, Proteggente A, Pannala A, Yang M, Rice-Evans C. Antioxidant activity applying an improved ABTS radical cation decolourization assay. Free Radical Biology and Medicine. 1999;26(9-10):1231-1237.
15. Singleton VL, Orthofer R, Lamuela-Raventos RM. Analysis of total phenols and other oxidation substrates and antioxidants by means of folin-ciocalteu reagent. Methods in Enzymology. 1999;299:152-78.
16. Smith AR, Shneider O, Le Bourn M, Sullivan R. Characterization of phenolic compounds and antioxidant capacity of beetroot pomace extracts. Foods. 2020;9(5):594.
17. Stintzing F, Scheibar A, Carle R. Evaluation of Colour properties and chemical quality parameters of cactus juices. European Food Research and Technology. 2003;216(4):3003-311.
18. Williams B, Cuvelier ME, Berset C. Use of free radical method to evaluate antioxidant activity. Academic press limited; 2005:25-30.
19. Yashwant K. Beetroot: A super food. International Journal of Engineering Studies and Technical Approach. 2015;1(3):20-26.
20. Zhishen J, Mengcheng T, Jiamming W. The determination of flavonoidcontents in mulberry and their scavenging effect on superoxide radicals. Food Chemistry. 1999;64:555-59.
21. Abdo MT, El-Ahmady SH, Gad HA. Quality control and long-term stability study of ginger from different geographical origins using chemometrics. Journal of the Science of Food and Agriculture. 2020;101(8):34293438.https://doi.org/10.1002/jsfa.10973