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The main purpose of this paper is to determine the content of amino acids, fatty acids and minerals in seven indigenous leafy vegetables (ILVs) in Ghana.

Leaves from plants growing near Kumasi were milled to a fine powder, dried to constant weight in a vacuum desiccator, and analyzed for their content of the afore‐mentioned nutrients. The plants were: Hibiscus sabdarifa, Hibiscus cannabinus, Amaranthus cruentus, Corchorus oliforius, Solanum macrocarpon, Xanthomosa sagittifolium and Vigna unguiculatus.

All seven ILVs contained a large amount of protein (15.5‐22.8 percent), which compared favorably to the essential amino acid pattern of a WHO standard. They all contained nutritionally useful amounts of α‐linolenic acid and had an omega‐6/omega‐3 ratio of 0.1‐0.9. The seven ILVs contained quantities of calcium, copper, iron, magnesium, manganese, molybdenum and zinc that could contribute significantly to satisfying an individual's need for these elements.

The presence of relatively large amounts of various nutritionally essential macro‐ and micronutrients in these seven ILVs does not necessarily mean these nutrients are bioavailable. Future research is required to determine the amounts of anti‐nutrients (e.g. protease inhibitors, chelators) in these vegetables, and the extent to which their protein, lipid and mineral constituents are digested and/or absorbed.

Since malnutrition (e.g. iron‐deficiency anemia, rickets, zinc deficiency, protein‐calorie malnutrition) is common in sub‐Saharan Africa, the information which is provided should increase awareness among agricultural and public health officials of the nutritional value of seven underappreciated and underutilized ILVs that are indigenous to Ghana and many other parts of Africa.

Natural dyeing has existed in human life from past to present. Although it lost its importance after the industrial revolution, it has started to make again a name for itself today with the increase in environmental awareness. The purpose of this study is to investigate whether the Hibiscus sabdariffa L. can be used in the coloring of woolen fabrics and as a natural antibacterial agent for these fabrics.

Within the scope of the study, it was investigated whether the antibacterial activity of the Hibiscus sabdariffa L. can be transferred to woolen fabrics. In the study, woolen fabric samples were dyed with and without mordant with the help of Hibiscus sabdariffa L. extract. After the dyed fabric samples were washed and dried, their color values were measured, and antibacterial effect tests (against Staphylococcus aureus – Escherichia coli), washing and rubbing fastness tests were carried out. In addition to these, scanning electron microscopy images of dyed fabric samples were taken and Fourier transform infrared microspectroscopy analyzes were also performed.

As a result of the study, it has been determined that the antibacterial activity of the Hibiscus sabdariffa L. can be transferred to woolen fabrics without the use of any chemicals.

Natural antibacterial agent for woolen fabrics was obtained within the scope of the study without the use of chemicals.

The purpose of this paper is to determine the physicochemical properties of oil produced from Roselle seeds.

The oil was produced from the seeds by mechanical expression and the physicochemical properties of the oil determined using the AOAC methods.

The values of the physicochemical properties of oil from Roselle seed are saponification value 126.2, iodine value 111.2, viscosity 22.5 cp, refractive index 1.4472 and specific gravity 0.9558. The peroxide value varied between 6.0‐9.3 and 5.9‐9.0; and free fatty acid, 0.435‐2.300 and 0.510‐3.311 for fine and coarse samples, respectively. These values compared favourably with standard values, indicating that the oil extracted is edible.

The properties are useful in determining the suitability of the oil from the Roselle seeds as edible oil or for other industrial purposes.

This paper aims at examining the potentiality of using Hibiscus sabdariffa L. calyces’ (Hs) aqueous extract to remove soot stains from the surface of fire-damaged silver gelatin prints. It further studies the cleaning efficiency and impact of both a contact method and a noncontact method with argon dielectric barrier discharge plasma (DBD Ar. plasma) on the different properties of silver gelatin prints. Accordingly, it prompts using economic, eco-friendly materials and methods in the photograph conservation field.

To achieve the aims of this paper, four silver gelatin prints were stained with soot and treated with the Hs aqueous extract as a contact method and DBD Ar. plasma combined with the aqueous extract as a noncontact method. The assessment was carried out using digital microscopy, atomic force microscopy and spectrophotometer to study the efficiency of the tested treatments and their impact on the surface of the photographs. Fourier transform infrared was used to monitor the state of the binder after cleaning. Furthermore, the pH and the mechanical properties were measured.

The contact method resulted in lower concentrations of Hs extract that efficiently cleaned the surface without causing any stains or damage to the treated photographs. The noncontact method (plasma with an aqueous extract) proved to be less effective in cleaning and made the binder more susceptible to deterioration.

This paper reveals the success of Hs aqueous extract in cleaning soot on vulnerable photographs' surfaces.

The purpose of this paper is to develop a new water based coating system composed of poly(acrylamide‐co‐acrylic acid) and anthocyanin colourant extracted from Hibiscus sabdariffa L. and characterise the system.

Anthocyanin from Hibiscus sabdariffa L. (roselle) calyxes was extracted using optimised water extraction method with ratio of calyxes to water being 1:2. UV‐Vis absorption spectroscopy was conducted on the anthocyanin extract to monitor its degradation. Poly(acrylamide‐co‐acrylic acid) was mixed with the extracted anthocyanin solution in two different weight ratios. The mixtures were coated on glass substrate and let to cure for approximately one day. FTIR spectroscopy was conducted on the samples to determine their functional groups and identify the compounds in the samples. Cross hatch test was performed on the samples to determine the adhesion properties. Thermal degradation of the samples was determined through thermogravimetric analysis. Surface roughness of the samples was studied by atomic force microscopy. Colour stability was determined before and after UV irradiation.

Anthocyanin pigment from roselle extracted with water was found to be stable with 6.0 per cent drop in absorbance value over the 15 day period. The reaction rate was found to be 0.000181 h⁻¹, and the half life was calculated to be 3,850 hours. Better adhesion of the samples to the glass substrate was due to the higher concentration of poly(acrylamide‐co‐acrylic acid). Thermogravimetric analysis revealed similar thermal stability of the samples. Surface roughness study revealed that sample with higher anthocyanin content has higher surface roughness. Colour stability of the 20PBR was found to be better than 10PBR.

Usage of poly(acrylamide‐co‐acrylic acid) as coating is limited by its weak water resistance property. Improvement could be made in this direction for future applications.

Mixture of water‐based polymer and anthocyanin colourant from roselle has been developed into coating for the first time. Commercialisation is possible if more research is conducted towards water resistance property of poly(acrylamide‐co‐acrylic acid), storage condition for the pigment and coating, and mass production of the pigment.

Incorporation of anthocyanin pigment into water based coating is the first of its kind.

The purpose of this study is to evaluate the effect of Hibiscus sabdariffa ethanolic extract (HsE) on protein levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, adiponectin and leptin in adipose tissue, as well as on the lipid and glycemic profiles of high-fat/sugar diet-induced obese (DIO) rats.

Obesity was induced in male Wistar rats through a high-fat/sugar diet provided for eight weeks. Control rats received a standard diet. The high-fat/sugar DIO animals were subsequently randomized into DIO (n = 8) and DIO treated with HsE (DIO + HsE, n = 8, 150 mg/kg/day) by gavage, for additional eight weeks. Oral glucose tolerance test was performed, and blood samples and epididymal adipose tissue were collected for biochemical analysis and adipokine protein level evaluation, respectively.

Compared to the DIO rats, HsE treatment decreased weight gain (50.6%) and mesenteric fat (42%), indicated as diminished visceral fat (22.5%). HsE did not affect the lipid profile and TNF-α levels in adipose tissue; however, it effectively prevented a 13% increase in fasting glucose levels and improved glucose tolerance. Compared with the C group, HsE normalized the adiponectin levels and leptin/adiponectin ratio and decreased the IL-6 (55%) and leptin (18.6%) levels in adipose tissue of obese rats.

HsE improves adipokine protein levels in high-fat/sugar DIO rats, demonstrating the clinical efficacy of HsE in the treatment of obesity and obesity-related diseases.

A study was conducted to determine the antioxidative properties of roselle (Hibiscus sabdariffa L.) methanol extract by monitoring the formation of diene‐conjugated compounds and thiobarbituric acid reactive substances (TBARS) in linoleic acid model system. The properties were compared to those of butylated hydroxy‐anisole (BHA) and α‐tocopherol. Results indicated that the roselle extract showed stronger antioxidant properties than BHA or α‐tocopherol. A total of 200 parts per million (ppm) of the extract inhibited more than 85 per cent of diene‐conjugated compounds after seven days of incubation at 40^○C. The total phenolic compound was found to be 2.96mg/g calyx as gallic acid equivalent. This indicates that roselle is a good source of natural antioxidants which may protect the body from damage by free radicals and lipid peroxidation. The protective effect is probably through the action of highly bioavailable ascorbic acid, β‐carotene and phenolic compounds, especially the anthocyanins.

The efficacy of roselle as a functional food has been revealed lately, especially for its antioxidant bioactivity. In this study, the benefits of roselle were further studied in vivo using the model of male Sprague Dawley rats fed with normal diets (C), 2.5 percent roselle (R), 2.5 percent roselle with 15 percent soybean oil (RO) and 15 percent soybean oil (O) for 25 weeks. The results demonstrated that supplementation of roselle in the diets significantly (p < 0.05) reduced the gross body weight and increased the high‐density lipoproteins cholesterol (HDL‐C) compared to the rats fed with normal diets and oil diets, and reduced the level of triglycerides in the serum. Serum total cholesterol of R group decreased compared to C but increased in RO compared to O group. Significant increase (p < 0.05) of serum uric acid was observed in R group at week 15 and 20. Addition of roselle in oil diet significantly decreased (p < 0.05) the malondialdehyde formation at week 20 and 25 but there was no significant effect of roselle on the catalase activity among the treatments at all time points. Suggests that roselle might play a role in the prevention of atherosclerosis and obesity.

In Nigeria, roselle juice is quite popular among the populace presumably owing to its attractive colour, pleasant flavour and nutritional attributes. In the citrus industry, processing and packing material selection have significant effect on quality of juice product during storage. The effects of packaging materials, and storage temperature on colour and vitamin C retention of sobo juice extracted from local roselle plant were investigated.

Juice was extracted at three different temperatures: 20, 60 and 100°C for varying processing times of 5, 10, 15, 20 and 25 min respectively. Freshly extracted roselle juice was divided into three batches and independently hot‐filled into 500 mL pre‐sterilised glass, film packages and polyethylene terephthalate (PET) bottles allowing for minimum head space, capped, cooled and subsequently stored at 5 ± 1 and 28 ± 1°C respectively for eight weeks.

Optimum pigment extraction was obtained in 20 min with boiling water, while colour stabilisation of the extracted juice was affected with the use of food acidulants. Colour degradation on storage was pronounced in sweetened juice with greater colour loss in product held at ambient temperature. Colour and vitamin C retention with glass and plastic bottles provide higher retention of these quality attributes under cold and ambient storage condition than with the flexible polyethylene film.

Retention of colour and vitamin C was considerably higher in glass and PET bottles than in flexible film package. However, addition of table sugar or increasing storage temperature from 5 to 27°C affected colour stability.

The purpose of this paper is to develop a new water‐based coating system composed of poly(vinyl alcohol) and anthocyanin colourant extracted from Hibiscus sabdariffa L. and to characterise the system.

Anthocyanin from Hibiscus sabdariffa L. (roselle) calyxes was extracted by using distilled water and filtered to remove insoluble particle. Salts introduced into the extract were 5wt percent calcium nitrate, 5wt percent magnesium nitrate, and 5wt percent zinc nitrate. The solution was mixed with poly(vinyl alcohol) in ratio of 3:1. The mixtures were coated on glass substrate and allowed to cure for approximately one day. Colour of the extract systems was determined by CIELab colourimetry. FTIR spectroscopy was conducted on the samples to identify their functional groups and changes upon addition of salt. Thermal stability was assessed by thermogravimetric analysis (TGA). Differential scanning calorimetry (DSC) was employed to measure the glass transition temperature Tg of the samples. XRD was employed to determine the amorphous properties of the coating samples.

From FTIR spectroscopy, shifting in the OH stretching and CH2 bending bands was attributed to hydrogen bonds formation between PVA and nitrate salt. Shifting in the main decomposition step in samples with addition of nitrate salts in TGA was due to interaction of PVA and nitrate. Increase in glass transition temperature of samples with salts was attributed to the formation of hydrogen bonding. From XRD study, increase in the amorphous properties was due to the incorporation of nitrate salts into PVA coating.

Limitation of implementating poly(vinyl alcohol) as coating is caused by its weak water resistance and hydrophilic properties. This study could bring about research towards incorporation of different natural colourant with different binder materials to form coatings which are environmental‐friendly and low cost.

Mixture of PVA and anthocyanin colourant from roselle for use as coating has been developed. The coating can find usage in various applications such as coloured coating for furniture and wooden materials for decorative purposes, biodegradable design materials for interior purposes. It can be practically applied on a variety of substrates such as glass and wood.

Development of water‐based coating from PVA binder with anthocyanin colourant is introduced in this study.