Functional properties of roselle (Hibiscus sabdariffa L.) seed and its application as bakery product

A Sustainable Approach: Repurposing Red Beetroot Peels for Innovative Meringue Products

With the increasing global demand for sustainable and eco-friendly food items, it is imperative to investigate alternate sources of natural pigments. The red beetroot (Beta vulgaris L.) is a traditional food in many countries and a rich bioactive compound known for its beneficial properties. Beetroot peel, a by-product of beetroot food processing, is often discarded, contributing to environmental damage. This research explores the potential of beetroot peel (BP) powder as a natural pigment in food products and its functional benefits. The study focuses on incorporating BP powder into meringues, aiming to create a value-added product with enhanced properties, particularly antioxidant activity. Various amounts of BP powder (4-10%) were added to meringue formulations, and the effects on the resulting meringues' physicochemical properties, sensory qualities, and phytochemical profiles were assessed during 21 days of storage. The research revealed that BP powder, besides its function as a natural colorant and the pleasing pink hue it imparts to meringues, also enhances antioxidant activity due to its high phenolic concentration. BP powder was also incorporated to enhance the meringues' overall sensory characteristics, improving their flavor and texture. The research findings indicate that BP has the potential to be used as a natural food ingredient to promote human health, resource-use efficiency, and a circular economy.

The Potential of Roselle (Hibiscus sabdariffa) Plant in Industrial Applications: A Promising Source of Functional Compounds

Roselle is an annual botanical plant that widely planted in different countries worldwide. Its different parts, including seeds, leaves, and calyces, can offer multi-purpose applications with economic importance. The present review discusses the detailed profile of bioactive compounds present in roselle seeds, leaves, and calyces, as well as their extraction and processing, to explore their potential application in pharmaceutical, cosmetic, nutraceutical, food and other industries. Roselle seeds with high phenolics, fiber, and protein contents, which are suitable to use in functional food product development. Besides, roselle seeds can yield 17-20% of roselle seed oil with high content of linoleic acid (35.0-45.3%) and oleic acid (27.1- 36.9%). This unique fatty acid composition of roselle seed oil makes it suitable to use as edible oil to offer the health benefits of essential fatty acid. Moreover, high contents of tocopherols, phenolics, and phytosterols were detected in roselle seed oil to provide nutritional, pharmaceutical, and therapeutic properties. On the other hand, roselle leaves with valuable contents of phenols, flavonoids, organic acid, and tocopherols can be applied in silver nanoparticles, food product development, and the pharmaceutical industry. Roselle calyces with high content of anthocyanins, protocatechuic acids, and organic acids are widely applied in food and colorant industries.

Fusarium solani infection disrupts metabolism during the germination of roselle (Hibiscus sabdariffa L.) seeds

Fungal infections adversely influence the production and quality of seeds. Previously, Fusarium solani was reported as the causal agent of roselle (Hibiscus sabdariffa L.) seed rot. This study was designed to evaluate the effect of F. solani infection on the germination, biochemical composition, energy reserves, and antioxidant activity of roselle seeds because there is currently a lack of information on the relationship between seed metabolism and infection with F. solani. The results showed that roselle seeds infected with F. solani exhibited a ca. 55% reduction in overall germination. Additionally, the fungal infection decreased antioxidant activity, total phenolic content, protein, sugar (sucrose, fructose, and glucose), and some amino acid (glutamine, serine, and arginine) contents. In contrast, some metabolites were more abundant in infected seeds, including alanine (2.1-fold) and some fatty acids (palmitic acid and heptadecanoic acid by 1.1- and 1.4-fold, respectively). The infection-associated changes in fatty acid profile resulted in the ratio of unsaturated/saturated fatty acids being 2.1-fold higher in infected seeds. Therefore, our results reveal that F. solani infection remarkably altered the biochemical composition of roselle seeds, which may have contributed to the loss of germination and quality of roselle seeds.

A study on the use of sorrel seed flour (Hibiscus sabdariffa) for improving functionality of wheat flour bread

Bread presents one of the easiest opportunities as a food vehicle for delivery of nutritional and health-promoting benefits to large segments of the world population. However, its low nutritional status due to lack of balance of essential amino acids and inadequate macro- and micronutrients has necessitated recent interest in the development of high-protein hybrid breads (HPHB). Sorrel seed, an underutilized, neglected protein-rich seed holds promising nutritional and antioxidant potentials as source of good quality protein, dietary fibre and bioactive compounds. Furthermore, germination of plant seeds increases the bioavailability of these nutritional and bioactive compounds. Hence, this study has investigated the influence of germination time on nutritional, and functional properties of sorrel seed flour. Further, the amino acid profile, dietary fibre and rheological functionality of wheat-germinated defatted sorrel seed bread were assessed. The sorrel seed was germinated for 24-48 h and defatted. Thereafter, the germinated defatted sorrel seed flours were used to partially replace wheat flour using a linear replacement (w/w) of 95-80% wheat (W) and 5-20% germinated defatted sorrel seed (GS) flours to obtain W95:GS5; W90:GS10, W85:GS15 and W80:GS20. These composite flours and 100% wheat flour (control) were used to produce breads using standard recipe and methods. Results showed significant increase (P < 0.05) in crude protein, dietary fibre and mineral contents after 24 and 48 h germination of sorrel seed. While 24 h germination significantly (P < 0.05) increased WAC from 93.75% to 103.13%, further germination (48 h) caused a reduction of 26.67% (from 93.75 to 68.75%). In vitro protein digestibility of wheat flour decreased significantly (P < 0.05) as supplementation of germinated defatted sorrel seed flour increased. Supplementation of wheat flour with germinated defatted sorrel seed flour in bread production resulted in 51.84-121.42% significant (p < 0.05) increase in the protein content of wheat bread. Similarly, total essential amino acids, dietary fibre, mineral, and ash contents followed the same increasing trend. The in-vivo biological value which ranged from 82.10 to 89.40% was significantly higher (p < 0.05) than 58.30% obtained for the control (100% wheat bread) Thus, inclusion of germinated defatted sorrel seed flour in bread production may serve as a low-cost nutritional supplement for enhancing the nutritional profile and functional benefits of wheat bread.

Ultrasound application for the decontamination of roselle (Hibiscus sabdariffa L.) seeds: Influence on fungal inhibition and seed quality

Seed decay is a major problem caused by pathogens that adversely affect seed yield and quality in agricultural production. Herein, the effect of 28 KHz ultrasound treatment for 20, 40 and 60 min and 1.5% sodium hypochlorite solution for 20 min was assessed for the decontamination of roselle (Hibiscus sabdariffa L.) seeds. In addition, seed germination indices, seedling growth traits, total phenolic content and the activity of defense-related enzymes, viz. peroxidase, superoxide dismutase, catalase and malondialdehyde were measured in the treated seeds. An isolate of Fusarium solani was obtained from roselle seeds and identified as the causal agent of roselle seed rot based on morphological and molecular characteristics. After six days of seed storage, the microbial infection caused the highest seed rot in the control seeds on the average of 56.67%, whereas ultrasound treatment for 60 min could remarkably reduce the seed decay by 3.33%. At the end of seed storage, the fungal load showed the highest (7.72 Log CFU ml-1) and lowest (6.99 Log CFU ml-1) rates in the control and ultrasound treatment for 60 min, respectively. Total phenolic content was significantly increased in ultrasound treatment for 60 min compared to control and sodium hypochlorite treatments. Moreover, the activity of peroxidase, superoxide dismutase and catalase was noticeably improved in ultrasound treatment for 60 min. Furthermore, ultrasound treatment did not show any adverse effects on seed germination indices and seedling growth traits of the roselle plants. Overall, ultrasound treatment for 60 min could effectively decrease roselle seed decay and the fungal load without changing seed and seedling quality.

Effect of Beetroot Powder Incorporation on Functional Properties and Shelf Life of Biscuits

The demand for ready-to-use functional foods is high, which encourages manufacturers to develop new, nutritionally valuable products. As an excellent source of biologically active compounds, beetroot (Beta vulgaris L.) is considered to have highly beneficial effects on health. This research aimed to evaluate the impact of replacing spelt flour (SF) with 15%, 20% and 25% beetroot powder (BP). The physicochemical and functional properties of biscuits baked at different temperatures (150 and 170 °C) were followed at the beginning, and after 3 and 6 months of storage as standard conditions. Moisture content and water activity (aw) gave insight into the biscuits' shelf life. The value of aw from 0.35 to 0.56 indicated appropriate storability. Dietary fiber content in fresh biscuits ranged from 6.1% to 7.6%, protein from 9.2% to 8.9% and sugar from 30.6% to 35.9%. The content of betalain, total polyphenols and flavonoids, and antioxidant activity (DPPH, FRAP) increased with beetroot powder content incorporated. A slight decrease of all the mentioned parameters during the storage indicated satisfied retention of bioactive molecules. The content of prevalent phenolic compounds gallic and protocatechuic acid, identified by HPLC, decreased from 22.2-32.0 and 21.1-24.9 in fresh biscuits to 18.3-23.4 and 17.3-20.3 mg/100 g upon six months of storage, respectively. An increase of the L* and a* and a decrease of the b* coordinate values, compared with the control sample without beetroot values, was noticed as well as the expected level of their change during the storage. The obtained results indicated that biscuits enriched with beetroot powder showed a significantly improved functional, nutritional and antioxidant potential during storage.

Pretreatment of tamarind pericarp to increase antioxidant availability and its application in a functional food

Diverse researchers have considered by-products of food and agricultural processing industries as a source of antioxidants. Tamarind (Tamarindus indica) is a leguminous tree, native from tropical Africa bearing edible fruit. The fruit is composed of 30% pulp, 40% seed, and 30% pericarp. Currently, tamarind pericarp is a waste from tamarind processing (approximately 54,400 tons of pericarp in 2012 worldwide) and is contributing to environmental contamination. This research aimed to determine the effect of maceration, microwaves, and ultrasound on the increase in the antioxidant availability in tamarind pericarp and its incorporation as a functional ingredient in cookies (5 and 10% substitution). Antioxidant content, antioxidant activity, proximate, and sensorial analysis of the cookies were conducted. The microwave method was the best pretreatment compared with sonication and maceration since it showed 1.3-fold higher amounts of phenolic compounds and 1.2-fold higher antioxidant capacity. The 10% substitution of tamarind pericarp powder in cookies, significantly increased the fiber content (four-fold) and phenolic compounds content (2.6-fold) and the product presented good acceptance in a sensorial test. Thus, tamarind pericarp powder could be considered as an antioxidant and fiber source and could be used as a functional ingredient in food products.

Optimization xanthan gum, Roselle seed and egg white powders levels based on textural and sensory properties of gluten-free rice bread

A response surface methodology based on Box-Behnken design was deployed to optimize gluten-free bread formulation based on rice flour. Roselle seed powder (15, 25 and 35%), egg white powder (10, 20 and 30%) and xanthan gum (0.5, 0.75 and 1%) were selected as independent variables. The purpose of the optimization was to achieve maximum porosity and sensory properties as well as minimum hardness of bread samples. The results showed that the Roselle seed and egg white powders had a significant effect (p ≤ 0.05) on hardness, porosity and sensory characteristics of bread. However, xanthan gum did not show a significant effect (p > 0.05) on sensory properties. The design revealed the optimum formulation for gluten-free rice bread with low crumb firmness and improved porosity and sensory values by using 0.73, 30 and 25% of xanthan gum, Roselle seed and egg white powders, respectively. In addition, the optimized gluten-free bread showed higher nutritional properties in terms of total protein, ash, oil and fiber contents as well as lower staling rate compared to the control.

Phytochemical contents, antioxidant activity and functional properties of Raphanus sativus L, Eruca sativa L. and Hibiscus sabdariffa L. growing in Ethiopia

Information on phytochemical contents, antioxidant activity and functional properties of underutilized plants Figl (Raphanus sativus L.), Girgir (Eruca sativa L.) and Karkade (Hibiscus sabdariffa L.) grown in Benishangul Gumuz, Ethiopia are limited. In view of this, leaves and roots of Figl, leaves of Girgir, calyces and seeds of Karkade were evaluated following standard analytical methods. The total flavonoids, total anthocyanins, β-carotene and L-ascorbic acid contents were ranged: 5.28–35.97, 0.01–2.53, 0.15–0.42 and 0.28–1.49 (db mg/g), respectively. The total flavonoids content, total anthocyanins content and antioxidant capacity were high in the brown calyces of Karkade, but are low in the roots of Figl. The antioxidant activity of roots of Figl and seeds of Karkade were low. The effective inhibitory concentration (IC₅₀) toward 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity demanded from brown calyces of Karkade was low and the IC₅₀ was strong negatively correlated with β-carotene and L-ascorbic acid contents (i.e., achieve IC₅₀ with low amounts of these bioactive compounds). The ferric reducing antioxidant power was positively strong correlated with total flavonoids and anthocyanins content. The finding showed that calyces of Karkade can be used as a candidate to substitute synthetic antioxidants and food colorant in food, beverage and pharmaceutical industries because of their high antioxidant capacity, desired color and as a good source of phytochemicals. The study also showed that the leaves of Figl and Girgir were found to exhibit good sources of vitamin C, β-carotene with low bulk density. Because of these properties, they can be regarded as good candidate to supplement micronutrients particularly for vulnerable groups like infants and young children.

Physicochemical quality and sensory acceptance of toasts with partial replacement of wheat flour by maize biomass flour

The aim of this study was to assess physicochemical and sensory viability of toasts developed from the partial replacement of wheat flour (WF) by maize biomass flour (MBF). Different levels of MBF (0, 5, 10, 15 and 20 g 100 g^-1) were used. Data obtained were evaluated by univariate and multivariate analyses. The level of replacement of WF by MBF influenced all physicochemical properties of the toast. Moisture (5.67-7.12 g 100 g^-1), hardness (56.67-131.66 N), chroma of crust and crumb (29.86-30.27 and 19.76-25.83, respectively), and hue angle of crust and crumb (60.32°-64.79° and 81.41°-82.06°, respectively) were increased; and area (2286.4-1658.1 mm²), specific volume (3.47-1.83 mL g^-1) and luminosity of crust and crumb (62.39-59.67 and 65.49-62.54, respectively) were decreased as the level of substitution of WF by MBF increased. The toasts did not present microbiological risk. The formulations with higher sensory acceptance were 5 and 15 g 100 g^-1 of MBF, being considered rich in proteins (16.25 and 15.43 g 100 g^-1, respectively) and rich in dietary fibers (12.10 and 16.02 g 100 g^-1, respectively), therefore with high nutritional and functional values. The production of toasts with partial replacement of WF by MBF is feasible in relation to physicochemical and sensory characteristics, which it may stimulate exploitation of this by-product and sustainable production of baked goods.

Proximate, mineral, and anti-nutrient compositions of underutilized plants of Ethiopia: Figl (Raphanus sativus L.), Girgir (Eruca sativa L) and Karkade (Hibiscus sabdariffa): Implications for in-vitro mineral bioavailability

In Ethiopia, particularly in the Benishangul-Gumuz region, there are several underutilized plants like Figl (Raphanus sativus), Girgir (Eruca sativa) and Karkade (Hibiscus sabdariffa) which are cultivated and consumed only by the local communities. However, information on nutrient, anti-nutrient contents and mineral bioavailability of edible parts of these plants are limited. Given this, leaves and roots of Figl, leaves of Girgir, calyces and seeds of Karkade were evaluated for their proximate, mineral and anti-nutrient contents following the standard analytical methods. The result on dry matter basis revealed that protein contents (26.32 g/100 g) were high for brown seeds of Karkade, dried leaves of Figl (26.71 g/100 g) and Girgir (24.23 g/100 g). The fat and energy contents were high for seeds of Karkade (15.58-18.00 g/100 g; 371.64-376.69 kcal/100 g). The fiber content was high for dried leaves of Figl (28.39 g/100 g) and low for calyces of Karkade (15.33-16.54 g/100 g). There was a significant difference (p < 0.05) in terms of mineral contents. The dried leaves of Figl were high in calcium, sodium, potassium, and phosphorus contents while dried leaves of Girgir were high in iron and zinc contents. With exception of oxalate content, seeds of Karkade were low in tannin, phytate and alkaloid. The phytate: mineral ratio analysis showed the bioavailability of iron is likely to be inhibited from roots of Figl and calyces of Karkade; zinc bioavailability from calyces of Karkade which suggests processing for phytate reduction is important. The result showed the seeds of Karkade are good sources of protein, fat and energy with low antinutritional contents that may favor mineral bioavailability with potential for utilization in baby food formulations to alleviate protein energy malnutrition. The leaves of Figl and Girgir can also be exploited in different food formulations to improve macro and micronutrient deficiency.

Kenaf (Hibiscus cannabinus L.) Seed and its Potential Food Applications: A Review

Kenaf belongs to the family Malvaceae noted for their economic and horticultural importance. Kenaf seed is a valuable component of kenaf plant. For several years, it has been primarily used as a cordage crop and secondarily as a livestock feed. The potential for using kenaf seeds as a source of food-based products has not been fully exploited. Consumers are becoming more interested in naturally healthy plant-based food products. Kenaf seed, the future crop with a rich source of essential nutrients and an excellent source of phytocompounds, might serve suitable roles in the production of value-added plant-based foods. At present kenaf seed and its value-added components have not been effectively utilized for both their nutritional and functional properties as either ingredient or major constituent of food products. This review focuses on the possible food applications of kenaf seed and its value-added components based on their nutritional composition and functional properties available in literature, with the purpose of providing an overview on the possible food applications of this underutilized seed. The review focuses on a brief introduction on kenaf plant, nutritional function, lipids and proteins composition and food applications of the seed. The review elaborately discusses the seed in terms of; bioactive components, antioxidants enrichment of wheat bread, antimicrobial agents, as edible flour, as edible oil and a source of protein in food system. The review closes with discussion on other possible food applications of kenaf seed. The need for food scientists and technologists to exploit this natural agricultural product as a value-added food ingredient is of great significance and is emphasized.

Technologies for enhancement of bioactive components and potential health benefits of cereal and cereal-based foods: Research advances and application challenges

Cereal grains are a major source of human food and their production has steadily been increased during the last several decades to meet the demand of our increasing world population. The modernized society and the expansion of the cereal food industry created a need for highly efficient processing technologies, especially flour production. Earlier scientific research efforts have led to the invention of the modern steel roller mill, and the refined flour of wheat has become a basic component in most of cereal-based foods such as breads and pastries because of the unique functionality of wheat protein. On the other hand, epidemiological studies have found that consumption of whole cereal grains was health beneficial. The health benefit of whole cereal grain is attributed to the combined effects of micronutrients, phytochemicals, and dietary fibre, which are mainly located in the outer bran layer and the germ. However, the removal of bran and germ from cereal grains during polishing and milling results in refined flour and food products with lower bioactive compounds and dietary fibre contents than those from whole grain. Also, the level of bioactive compounds in cereal food is influenced by other food preparation procedures such as baking, cooking, extrusion, and puffing. Therefore, food scientists and nutritionists are searching for strategies and processing technologies to enhance the content and bioavailability of nutrients, bioactive compounds, and dietary fibre of cereal foods. The objective of this article was to review the research advances on technologies for the enhancement of bioactive compounds and dietary fibre contents of cereal and cereal-based foods. Bioactivities or biological effects of enhanced cereal and cereal-based foods are presented. Challenges facing the application of the proposed technologies in the food industry are also discussed.

Physicochemical Properties and Oxidative Storage Stability of Milled Roselle (Hibiscus sabdariffa L.) Seeds

Milled Roselle (Hibiscus sabdariffa L.) seeds of the UMKL cultivar were analyzed for proximate composition, water and oil absorption capacity, and the influence of storage conditions on storage stability. The storage stability was determined under four types of conditions: light/oxygen (air) (LO), light/nitrogen (LN), darkness/oxygen (air) (DO), and darkness/nitrogen (DN) while monitoring for seven consecutive months. During the storage period, the formation of volatiles was determined using dynamic headspace sampling and Gas Chromatography-Mass Spectrometry (GC-MS) analysis. In total, 85 volatiles were identified, mainly aldehydes, alcohols, ketones, furans, and acids indicating lipid oxidation. It is recommended that milled Roselle seeds should be flushed with nitrogen and stored in darkness. Under these conditions, the seeds can be stored for at least three months without changes in volatile profile. This is important to ensure the good quality of milled Roselle seeds for further commercialization.

Hibiscus sabdariffa L. and Its Bioactive Constituents Exhibit Antiviral Activity against HSV-2 and Anti-enzymatic Properties against Urease by an ESI-MS Based Assay

For decades, Hibiscus sabdariffa L. and its phytochemicals have been shown to possess a wide range of pharmacologic properties. In this study, aqueous extract of Hibiscus sabdariffa (AEHS) and its bioactive constituent protocatechuic acid (PCA), have been evaluated in vitro for their antiviral activity against HSV-2 clinical isolates and anti-enzymatic activity against urease. Antiherpetic activity was evaluated by the titer reduction assay in infected Vero cells, and cytotoxicity was evaluated by the neutral red dye-uptake method. Anti-urease activity was determined by a developed Electrospray Ionization-Mass Spectrometry (ESI-MS)-based assay. PCA showed potent anti-HSV-2 activity compared with that of acyclovir, with EC₅₀ values of 0.92 and 1.43 µg∙mL⁻¹, respectively, and selectivity indices > 217 and > 140, respectively. For the first time, AEHS was shown to exert anti-urease inhibition activity, with an IC₅₀ value of 82.4 µg∙mL⁻¹. This, combined with its safety, could facilitate its use in practical applications as a natural urease inhibitor. Our results present Hibiscus sabdariffa L. and its bioactive compound PCA as potential therapeutic agents in the treatment of HSV-2 infection and the treatment of diseases caused by urease-producing bacteria.