Department of Applied Chemistry and Chemical Technology, Chittagong Veterinary and Animal Sciences University for his effective guidance throughout my study period, plowing through several drafts of my text, making critical suggestions and posing provocative questions. I also extend my special thanks and sincere thanks to my beloved co-promoter Mohammad Mozibul Haque, Assistant Professor, Department of Applied Food Science and Nutrition, CVASU, for his guiding support and sincere cooperation during my research work. Special thanks are due to the director and the scientists involved in this research work of Poultry Research and Training Center (PRTC), Department of Applied Food Science and Nutrition, Department of Applied Chemistry and Chemical Engineering, Department of Animal Science and Nutrition, Department of Food Processing and Engineering, CVASU for their constant inspiration and kind cooperation in carrying out the research activities right in that laboratory.
Finally, I would like to express my deep gratitude and heartfelt thanks to my dear family, friends and well-wishers for their cooperation, cheerfulness and inspiration during the study. I gratefully acknowledge my beloved parents for their understanding, inspiration, moral support, kindness and blessings, forbearance and endless love to complete my studies. The study aimed to develop roselle marmalade from dark and pink varieties and to evaluate phytochemicals, antioxidant capacity, sensory and nutritional parameters.
The research was carried out by preparing rosella jam with the addition of sugar, commercial pectin, roselle seed extract as a natural pectin and citric acid. We found that the sensory evaluation of rosehip jam processed with the extract of the seeds of both varieties (sample B and sample E) is the best among the different formulations of the two varieties.
Introduction
Its calyxes have been proposed as food dyes for the food industry, emulsifier for carbonated beverages, jam, juice production, and natural food dyes (Duangmal et al., 2004). People are becoming more and more health conscious and are more interested in eating fruits and vegetables to maintain good health. It is an example of a fruit preserve, usually made from the pulp and juice of a single fruit (whole fruit), usually eaten as a spread on bread.
The preparation of fruit jam traditionally involves the use of pectin as a gelling agent, although sugar or honey and citric acid can also be added (Ihediohanma et al., 2014). It is also considered a safe supplement with no limits on acceptable daily intake (Da Silva and Rao, 2006). However, they are seasonal and highly perishable and need to be processed into more stable forms such as jams, jellies and juices to reap their maximum benefits (Sinha et al., 2012).
Where one attractive and effective way of fruit utilization is jam processing (Jalgaonkar et al., 2020). Page | 3 evaluation, microbial analysis, antioxidant and bioactive compounds of jam made from two varieties of Roselle (red and dark red).
Review of Literature
- Overview of Roselle
- Origin and distribution of Roselle
- Utilization and economic importance of Roselle
- Calyces
- Leaves and roots
- Stem
- Seeds
- Nutritional properties
- Functional properties and Phytochemicals
- Functional foods
- Functional foods from plant sources
- Phytochemicals
- Antimicrobial activity
- Medicinal and health benefits
- Roselle jam
The leaves are widely consumed in Myanmar as an affordable vegetable for poor people (Islam et al., 2016). An important risk factor for the development of cardiovascular disease is the elevated plasma cholesterol levels (Félix-Redondo et al., 2013). Polyphenols in beverages are common due to their beneficial physiological effects on health (Ina et al., 2002).
Antioxidant production can occur within the body as well as naturally in many foods (Alam et al., 2020). Due to their influence on sensory properties (color and astringency) their analysis in foods and beverages has been developed during the last decades (Monagas et al., 2005). Ash extracts reduced body fat and body mass index (BMI) (Greenwood-Robinson, 1999; Ghislain et al., 2011).
Roselle juice with salt, pepper and molasses is used to relieve cough and relieve biliousness (Mohamed et al., 2012). Roselle jam and jelly are also produced in different countries of the world and are available in superstores (Islam et al., 2016).
Materials and Methods
- Study Area
- Study Duration
- Collection of Sample
- Jam Preparation
- Physicochemical analysis of Roselle jam
- Determination of pH
- Total Soluble Solids
- Titratable Acidity
- Determination of Vitamin C
- Moisture content
- Total solids
- Ash content
- Estimation of Crude Fat
- Estimation of Crude Protein
- Estimation of Crude Fiber
- Determination of total carbohydrate
- Determination of Antioxidant capacity by DPPH scavenging method
- Determination of bioactive compounds
- Total Phenolic Content (TPC)
- Total Anthocyanin content (TAC)
- Total flavonoid content (TFC)
- Microbiological analysis
- Aerobic plate count (Bacterial plate count)
- Fungal analysis in jam
- Energy estimation
- Cost analysis
- Sensory evaluation
- Statistical Analysis
Total soluble solids of the fruits were found out with the help of hand refractometer. Moisture content was determined using the standard procedure of the Association of Official Analytical Chemists (AOAC, 2016). AOAC (2016) methods using a soxhlet apparatus were used to determine the crude fat content of the samples.
The determination of Kjeldahl nitrogen is done in food and beverages, meat, animal feed, grains and forage crops for the calculation of the protein content. The antioxidant mobility of the extracts was determined using the DPPH assay according to the method described by Azlim et al. The wash mobility was measured as the decrease in absorbance of the samples compared to the DPPH standard solution.
The TPC of the extracts was determined according to the Folin-Ciocalteu reagent method described with slight modifications (Al-Owaisi et al., 2014). The total polyphenol content (TPC) of rosella jam was determined according to the Folin-Ciocalteu method reported by Vergani et al. The color intensity of the extract was measured at 520 nm wavelength using UV-VIS spectrophotometer.
The total flavonoid (TFC) content of the samples was determined using the aluminum chloride colorimetric method reported by Chang et al. The absorbance was read at a wavelength of 415 nm in a UV-visible spectrophotometer (UV-2600, Shimadzu Corporation, USA) and 10% aluminum chloride substituted with an equal amount of D.H2O was used as a blank. Page | 24 sample was calculated by comparing the absorbance of sample extracts with a standard curve of quercetin.
The reliability of the analysis and the interpretation of the results largely depend on the correct method of sample collection. Approximately 100 mL of buffered saline was added to the beaker and mixed well by swirling. This data could be used as indicators of food quality or predictors of product shelf life.
The energy content of rosella jam was determined by calculating the amount of protein, fat and carbohydrate of the respective food items and using the following equation (Baer et al., 1997). Sensory evaluation is performed to determine the overall acceptability of the final product by consumers.
Results
- Physicochemical properties of jam
- Nutritional Composition
- Phytochemical composition of roselle jam
- Antioxidant capacity
- Microbial analysis
- Cost analysis
- Energy content
- Sensory evaluation
The nutritional value of Roselle jam is shown in Table 4.2, almost all samples are significantly different. Legends: Means ± SD and values in the same column with the same headings are not statistically significant (P > 0.05). The presence of yeast and mold was not found when the products were manufactured and after 15 days their presence had not been identified.
In the table, Sample A - Light red rosella jam without additional pectin, Sample B - Light red rosella jam with seed extract, Sample C - Light red rosella jam with commercial pectin, Sample D - Dark red rosella jam without additional pectin, sample E-jam in the form of dark red rosella with seed extract and sample F-jam in the form of dark red rosella with commercial pectin.
Discussions
- physicochemical properties of roselle jam
- Nutritional composition of jam
- Phytochemicals
- Antioxidant capacity
- Microbial Analysis
- Sensory Evaluation
The combination of pectin and seed extract with rosella calyx in the development of rosella jam provides essential nutrients such as protein, fat, fiber, CHO and vitamins. According to Ashaya and Adeleke (2009), the moisture content of dark red and light red variety jam was 31.39%. The moisture content of rosella jam can vary depending on storage conditions and the type of pectin used during cooking (Broomes and Badrie, 2010).
This significant change in nutrient composition for both varieties of rosella jam may be due to the addition of commercial pectin or seed extract. This study showed higher nutritional content than rosella jam prepared from rosella calyx extract, reported by Mordi et al. (2011). Ascorbic acid content increased from 14.16 to 28.82 mg/100 gm in rosella jam prepared from light and dark red rosella calyxes (Ashaye and Adeleke, 2009).
The quantification of these compounds is thus of utmost importance, and the results of the content of bioactive compounds found in roselle jam are shown in Table 4.3. The variation in the value of bioactive compounds in the same variety of jam may be due to change in the pectin concentration in the final product (Poiana et al., 2012). Antioxidant capacity was higher (mg TE/100 g) in sample B compared to control sample A for light red roselle jam.
This may be due to the seed extract used in sample B, as roselle seeds are a good source of fat-soluble antioxidants (Mohamed et al., 2007). It may be due to the addition of commercial pectin as Ogutu et al., (2017) observed that high pectin concentration increases antioxidant capacity. Heat and pH affect the antioxidant capacity of Roselle and its product (Wu et al., 2018) by as much as 65%.
Microbiological analyzes (Total Viable Count, Yeast and Mold Count) were performed for each of the six roselle jam samples. Sensory analysis of rosella jam was done to obtain the most acceptable organoleptic ally ratio among all jams. From the present research, it was concluded that roselle jam with seed extract in both varieties proved to be organoleptically better than the other compositions.
Conclusion
Recommendations and Future Perspectives
Investment potential of Hibiscus sabdariffa Linn (var.sabdariffa): a case study of Zobo liquor in south west Nigeria. Effects of low-methoxyl pectin on physicochemical and sensory properties of sorrel/roselle (Hibiscus sabdariffa L.) reduced calorie jams. Estimation of total flavonoid content in propolis by two complementary colorimetric methods. Journal of Food and Drug Analysis.
An evaluation of the hypolipidemic effect of an extract of Hibiscus Sabdariffa leaves in hyperlipidemic Indians: a double-blind, placebo-controlled trial. Nutritional and phytochemical composition, functional properties of Roselle (Hibiscus sabdariffa) and sensory evaluation of some beverages made from Roselle calyxes (Doctoral dissertation). Functional potential of a product of traditional biotechnology: antioxidant and probiotic potential of Mbuja, produced by fermentation of Hibiscus sabdariffa seeds in Cameroon.
Chronic administration of aqueous extract of Hibiscus sabdariffa attenuates hypertension and reverses cardiac hypertrophy in 2K-1C hypertensive rats.
