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BACKGROUND: Kenaf seeds are underutilized kenaf plant by‐products, containing essential nutrients including dietary fiber (DF), which can be potentially utilized as food ingredients. The present study aimed to evaluate the physicochemical characteristics of kenaf seed fiber fractions extracted from kenaf seed. RESULTS: Defatted kenaf seed powder yielded four DF fractions: alkali‐soluble hemicellulose (146.4 g kg−1), calcium‐bound pectin (10.3 g kg−1) and acid‐soluble pectin (25.4 g kg−1) made up the soluble fibre fraction, whereas cellulose (202.2 g kg−1) comprised the insoluble fraction. All fractions were evaluated for their physicochemical properties. The DF fractions contained glucose, mannose, xylose and arabinose, and a small amount of uronic acid (1.2–2.7 g kg−1). The isolated pectin fractions had a low degree of esterification (14–30%). All the isolated DF fractions had high average molecular weights ranging from 0.3 to 4.3 × 106 g mol−1. X‐ray diffractogram analysis revealed that the fractions consisted mainly of an amorphous structure with a relative crystallinity ranging from 31.6% to 44.1%. The Fourier‐transform infrared spectroscopy spectrum of kenaf seed and its DF fractions showed typical absorption of polysaccharides, with the presence of hydroxyl, carboxyl, acetyl and methyl groups. Scanning electron microscopy analysis demonstrated that the raw material with the rigid structure resulted in soluble and insoluble DF fractions with more fragile and fibrous appearances, respectively. The soluble DF demonstrated greater flowability and compressibility than the insoluble fractions. CONCLUSION: These findings provide novel information on the DF fractions of kenaf seeds, which could be used as a potential new DF for the food industry. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Summary: Tofu was made by substituting kenaf seed (K) with soybean (S) at 100 (positive control), 50%, 40%, 30%, 20%, 10% and 0% (negative control). The results indicated that kenaf seed substitution at all ratios significantly increased the soluble solids and protein content of the milky extracts. The yield, moisture and protein content of the tofu were significantly increased with the increase in kenaf seed substitution, while the lipid content was significantly decreased. The tofu made with kenaf seed substitution of 50%, 40% and 30% had the same protein content (43.76–45.36 g/100 g) with the positive control (45.36 g/100 g), but a significantly higher lipid content (32.00–35.75 g/100 g) than that of the positive control (27.50 g/100 g). The microstructure of the tofu revealed that only the positive control had a honey‐comb structure, whilst the tofu made from kenaf seed‐soybean blends had a pseudo‐honey like structure. Up to 30% of soybean can be added into the kenaf‐based tofu, without any negative effect on the textural and colour properties and, protein content, but significantly improved the essential amino acids content of the kenaf‐based tofu. Therefore, the blend of 70K:30S ratio using 0.5 g% glucono delta‐lactone as a coagulant is recommended to produce kenaf seed‐soybean tofu. [ABSTRACT FROM AUTHOR]

Kenaf (Hibiscus cannabinus L.) seed is an underutilized protein-rich resource considered as a by-product of the kenaf fiber processing industry. Its high protein content (34%) makes it a promising candidate as a source of bioactive protein hydrolysates. In this study, the potential of enzymatically hydrolyzed kenaf seed protein to generate multifunctional bioactive peptides was evaluated. Kenaf seed protein concentrate was hydrolyzed using four different proteolytic enzymes (papain, alcalase, bromelain, and flavourzyme) at their respective optimum pH and temperature. The choice of enzyme affected the bioactivities to a certain degree as KSPH were shown to possess high ACE inhibitory activity and low-to-moderate DPP-IV and antioxidant activity. Papain KSPH showed the highest ACE inhibitory activity with 95% inhibition compared to other enzymatic hydrolysates, and therefore was chosen for further investigation of its antihypertensive activity. Papain KSPH was profiled for its hydrophobicity by RP-HPLC and revealed that the majority of late-eluting fractions exerted the highest ACE inhibitory activity. Spontaneously hypertensive rats showed a decrease of approximately 18–46 mmHg in their systolic blood pressure (BP) from 0 to 24 h after oral administration of papain KSPH at dosages of 100 mg/kg, 300 mg/kg, and 500 mg/kg. However, the effect was not dose-dependent. As a novel protein source, future research should aim to demonstrate the safety of kenaf seed protein and its hydrolysates, and validate its bioactivity through human intervention trials. Overall, kenaf seed protein has the potential to generate antihypertensive hydrolysates with multifunctional bioactivities as part of a functional food ingredient. [ABSTRACT FROM AUTHOR]

The effects of soaking temperature of kenaf seed on the proximate, phytic acid, and microstructure were studied to produce kenaf‐based tofu. The seeds were soaked at temperatures 65°C, 45°C, and 25°C for 160, 300, and 616 min, respectively. The soaked seeds were used to produce tofu based on the Box–Behnken design with three independent variables (coagulant types (x1), coagulant concentrations (x2), and soaking temperature of seed (x3). Soaking significantly increased the carbohydrate and reduced the ash content without a significant effect on the phytic acid of the seeds. An increase in the soaking temperature of seed significantly decreased the yield, hardness, and chewiness of the tofu. Two‐way interactions of (x1x2) and (x1x3 and x2x3) significantly affected the yield and the hardness of the tofu, respectively. There was a 75.91%–100% reduction in the phytic acid of the tofu. Hydrogen and hydrophobic interactions were the major bonds that stabilized the coagulation process of the tofu. Practical applications: Kenaf seed contains a high amount of protein and it could serve as a suitable seed for tofu production. In general, processing factors are an important concern in tofu making. Soaking is a crucial step in the production of tofu which is often time‐consuming. Soaking of seeds at higher temperature is known to practically reduce the time of soaking and overall processing time. Different types and concentrations of coagulants will give different effects on the characteristics of the tofu. The results showed that the soaking temperature of kenaf seed, coagulant types, and concentrations used in the tofu preparation affected the textural characteristics of the product. Hardness and chewiness of the tofu were significantly decreased as the soaking temperature of the seed was increased. The findings of this research will serve as the primary knowledge to produce tofu from kenaf seed. Application of suitable kenaf seed soaking conditions and appropriate concentration and type of coagulant will be useful for the tofu manufacturers to produce kenaf‐based tofu with desirable qualities. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

[Display omitted] • Kenaf seed beverage (KSB) possessed less protein, fat, sugars, and lipid peroxidability; and higher total carbohydrate, minerals, sugars, phenolic contents, and antioxidant activities than soybean beverage (SB). • Antinutritional compounds tannins and oxalates were higher in KSB, but lower in phytates, oxalates, and total saponins compared to SB. • UHPLC-MS analysis detected caffeic gluconic acid, citric acid, palmitic acid, oleic acid, and 13-hydroxyoctadecadienoic acid in both KSB and SB. • No acute and subacute oral toxic effects were found after KSB consumption in rats up to 9.2 ml/kg body weight dosage. Kenaf (Hibiscus cannabinus L.) seed is a non-conventional edible oilseed that can be valorized into various food products. There is a recent discovery of kenaf seed beverage (KSB) potential as a novel plant-based beverage. KSB had less crude protein than soybean (SB) but more carbohydrate, magnesium, and phosphorus contents. Levels of crude fat, phytates, oxalates, total saponins, and lipid peroxidability in KSB were lower than SB. Sugar content between KSB and SB were comparable, while antioxidant properties of KSB were superior. Ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) analysis detected gluconic acid, citric acid, palmitic acid, oleic acid, and 13-hydroxyoctadecadienoic acid in both KSB and SB. Considering its novelty, acute and subacute oral toxicity assessments in male Sprague Dawley rats were conducted. The acute toxicity assessment was performed at a single dose of 9.2 ml/kg body weight of KSB. In the following subacute toxicity assessment, different groups of rats consumed different doses of KSB (3.1, 6.1, and 9.2 ml/kg body weight) daily for 28 days. Rats presented normal behavioral and physiological states in both toxicity studies. Growth, food and water intakes, organ weight, and hematological parameters were unaffected. No mortality was reported. Several alterations in serum biochemical parameters were within the normal range, and unassociated with histopathological changes. The oral lethal dose (LD 50) and the no-observed-adverse-effect-level (NOAEL) of KSB in rats was greater than 9.2 ml/kg (=1533 mg/kg) body weight. Interestingly, KSB exhibited comparable effects with soybean beverage (SB) on high-density lipoprotein cholesterol and triglycerides which worth further research Follow-up toxicity assessments in animals and human trials are also recommended to ascertain its long term safety. [ABSTRACT FROM AUTHOR]

Kenaf seed meal protein concentrate (KSPC) and lyophilized kenaf seed milky extract protein concentrate (KSMEPC) were obtained via alkaline extraction. The proximate compositions, amino acids and functional properties of both concentrates were compared. KSPC was found to be significantly higher in protein, essential and non-essential amino acids but, lower in lipid and carbohydrate contents than KSMEPC. The solubility, water absorption capacity and denaturation temperature of KSPC and KSMEPC were similar. However, KSMEPC had significantly higher oil absorption capacity, foam capacity and stability, and a significantly lower emulsion property than KSPC. The heat coagulability and coagulation capacity of the protein concentrates were not significantly different. But, the heat coagulability was significantly increased as the concentration of the protein concentrates increased from 4 to 20%. This study showed that kenaf seed may be considered as a potential ingredient in food products like tofu, meat extender, butter and mayonnaise. Image 1 • Extraction steps affected the amino acids profile of kenaf seed milky extract. • Protein concentrate from kenaf seed meal had better emulsion capacity and stability. • The heat coagulability and coagulation capacity of the concentrates were concentration-dependent. • On the bases of the thermal stability of the concentrates, they are potential ingredients in meat extenders. • Based on their heat coagulability they are potential ingredients in tofu making. [ABSTRACT FROM AUTHOR]