Sriyana Abdullah
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Preferred name
Sriyana Abdullah
Official Name
Sriyana, Abdullah
Alternative Name
Abdullah, S.
Main Affiliation
Scopus Author ID
57215616236
Researcher ID
CBB-0793-2022

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  • Publication
    Thin layer drying characteristics and its influence on the physical properties and bioactive compounds of Misai Kucing plant (Orthosiphon staminues) leaves
    ( 2015)
    Sriyana Abdullah
    O. stamineus or locally known as misai kucing is a Malaysian herbal plant, popular as a traditional medicine especially in the Southeast Asian region. It is believed to treat urinary tract diseases, kidney stones and many other human illnesses. Since this herb is stored and consumed in its dried form, knowledge of thin layer drying characteristics is important. The thin layer drying characteristics studies included moisture sorption behavior, drying kinetics and effects of drying conditions on final quality of O. stamineus leaves. Adequate knowledge of the drying characteristics provides appropriate final samples moisture content, thus decreases drying time, mass losses, risk of quality degradation, and reduces energy consumptions. In this work, the moisture sorption behavior was studied by developing moisture sorption isotherms at temperatures of 5 oC and ambient (about 30 oC) and at 5 levels of relative humidity ranging from 11.3 % to 75.7 % by a static gravimetric method. The thin layer drying characteristics of O. stamineus were evaluated at temperatures of 30, 40 and 50 oC and at air velocities of 0.8 and 1.3 m/s using a fabricated laboratory scale hot air dryer. A mathematical modeling was performed using a statistical software package to compare experimental data with predicted data for both moisture sorption isotherms and drying kinetics. Five widely used moisture sorption models, namely Oswin, Peleg, Guggenheim-Anderson-de-Boer (GAB), Brunauer, Emmett, & Teller (BET) and Chung & Pfost models and seven widely used thin layer drying models, namely Lewis, Page, Modified Page, Handerson & Pabis, Midili & Kucuk, Two Term Exponential and Wang & Singh were chosen. Color quality, total phenolic content and biomarker compounds (i.e. RA, SEN and TMF) concentration were determined to represent the final dried leaves quality. The moisture sorption isotherms of O. stamineus were found to be of Type III isotherm (J-shaped).The comparison between the experimental data and the predicted data of the moisture sorption isotherms was found to be closely followed the Peleg model, whereas, the thin layer drying kinetics closed to the Midili & Kucuk model. The thin layer drying of O. stamineus leaves took place in a falling rate period only.
  • Publication
    Changes in the physical and chemical properties of C. nutans herbal leaves dried under different drying methods
    ( 2021-05-24)
    Sriyana Abdullah
    ;
    Rafidah Nordin
    ;
    Rzemin M.A.A.
    ;
    Norawanis Abdul Razak
    Drying is a well-known preservation method that uses to extent the shelf life of food materials during storage. In herbal industry, the drying is conducted by using several methods. It is believed that drying methods could affect the herbs physical and chemical properties. In this project, the effects of different drying methods on colour changes, rehydration ratio and bioactive constituent of C. nutans herb were investigated. The herb was dried under sunlight, shade, vacuum oven, and microwave. Results showed that the dried leaves have better retention of TPC and higher antioxidant activity as compared to the fresh leaves. Vacuum oven dried samples showed the highest antioxidant activity and significantly high in TPC. Besides, vacuum and under shade dried herbal leaves had no significant effect on the colour changes. Moreover, leaves dried under vacuum oven was also observed to exert the highest rehydration ratio due to less cell breakdown during drying. Therefore, vacuum drying has greater performance in term of retaining colour, less microstructure changes and greater TPC and antioxidant activity. It could be suggested that by adding vacuum to other drying methods may able to enhance the herbal quality.
  • Publication
    Estimating shelf-life of fresh Brazilian spinach: Paper and plastic packaging
    ( 2023-04-24)
    Norawanis Abdul Razak
    ;
    Amran M.A.F.
    ;
    Sharon S.
    ;
    Wei L.T.
    ;
    Abd Razak Shaari
    ;
    Lee Yit Leng
    ;
    Ras Izzati Ismail
    ;
    Sriyana Abdullah
    The selection of packing materials is an important factor to prolong the shelf life of food products, especially for perishable foods or produces. This research was conducted to determine the effect of packing materials (papers and plastics) on fresh Brazilian spinach leaves quality such as moisture content, water activity and total color difference (Δη). The samples were stored at ambient temperature (25 °C) for 16 days. The moisture content and water activity of the samples were measure by moisture analyzer and water activity meter, respectively. The total color difference (Δη) was calculated based on L∗, a∗ and b∗ parameters. Generally, based on overall results, the packing materials significantly affected the quality of fresh Brazilian spinach leaves throughout 16 days of storage period. The results asserted that the paper materials are not suitable to use to pack fresh Brazilian spinach leaves for long period. It is also not recommended to use any paper material to pack fresh produce, especially perishable vegetables and fruits, in protecting their quality. The use of HDPE and PP plastics is recommended to prolong the shelf life of the fresh Brazilian spinach leaves. However, it has a limitation in controlling the changes of leaves color.
  • Publication
    Infrared drying of Clinacanthus nutans leaves
    ( 2022-03-01)
    Sriyana Abdullah
    ;
    Yusof Y.A.
    ;
    Rukunudin I.H.
    ;
    Abdul Karim Shah N.N.
    ;
    Norawanis Abdul Razak
    Clinacanthus nutans herbal leaf was dried using an infrared dryer under different power levels (100 W, 200 W, and 300 W) and at different distances between infrared source and samples (10 cm, 20 cm, and 30 cm). Results showed that the drying rate increased when power levels increased and distances decreased. There were found that Midili and Kucuk, Modified Henderson and Pabis, Verma, Two Term, and Wang and Singh gave the best fitting to the experimental moisture ratio for a specific drying treatment. The moisture diffusivity values determined were 4 Ã— 10−11 to 3.09 Ã— 10−10 m2/ s and the activation energy values ranged from 30.81 to 50.58 W/g. Infrared drying can be an option for quick preservation technique for C. nutans herbal leaves as it gave a shorter drying time which could optimize the energy usage. Novelty impact statement: The drying rate of C. nutans leaves was able to increase at a faster rate by infrared radiation as compared to the conventional methods. This result gave a significant reduction of drying time that may reduce energy consumption and enhance the physicochemical properties of the herb.
  • Publication
    Synthesis and characterization of carboxymethyl cellulose derived from office paper waste for methylene blue dye removal
    ( 2021-02-23)
    Nor Aida Yusoff
    ;
    Yee L.Y.
    ;
    Nur Izzati Iberahim
    ;
    Noor Ainee Zainol
    ;
    Sriyana Abdullah
    ;
    Siti Nazrah Zailani
    The aim of this research was to extract cellulose from office paper waste and converted into carboxymethyl cellulose (CMC) based flocculant to treat methylene blue (MB) dye solution. The yield of extracted cellulose obtained was 62.17%. Three different CMC samples were prepared. Degree of substitution (DS) for CMC-1 is 0.6585, CMC-2 is 0.8124 and CMC-3 is 0.8946. This proved that CMC are substituted into cellulose structure due to the DS of the commercial CMC are in the range of 0.4 to 1.5. The coagulation flocculation process of the MB dye shows that the CMC-3 was effective for methylene blue dye removal with highest percentage (98.14%) at pH 9.0, flocculant dosage of 210 ppm with 100 ppm MB concentration solution.
  • Publication
    Mathematical modelling of moisture sorption isotherms by using BET and GAB models
    ( 2020-12-18)
    Sriyana Abdullah
    ;
    Keoh S.C.
    ;
    Hafizah Mohd Johar
    ;
    Norawanis Abdul Razak
    ;
    Abd Razak Shaari
    ;
    Rukunudin I.H.
    Fish cracker is a popular local fish based snack in Malaysia. Besides the raw form which can be consumed directly, it is always eaten in the dried form. Thus study of moisture sorption isotherm of fish cracker is essential as to predict appropriate drying and storage conditions consecutively to enhance its nutrients, taste and aroma. In this study, the moisture sorption isotherms of fish crackers from two manufacturers M1 and M2 were developed by using a static gravimetric method at temperatures of 30, 40 and 50°C and water activity (aw) range of 0.04 to 0.80. It is a relationship between equilibrium moisture content (EMC) and aw at a specified temperature. The isotherms exhibited a sigmoid shaped which classified as type II in Brunauer-Emmett-Teller (BET) classification. The increase of temperature decreased the EMC of fish crackers while increase of aw increased the EMC. There was no significant difference of EMC between manufacturers M1 and M2. The moisture sorption isotherms of fish cracker were fitted into predicted isotherms by Guggenheim-Anderson-de Boer (GAB) and BET models. GAB model was found to be the best fit model of fish crackers' moisture sorption isotherms as compared to BET model.
  • Publication
    Hot air drying of Brazilian spinach leaves
    ( 2024-03)
    Norawanis Abdul Razak
    ;
    Lim Teik Wei
    ;
    Lee Yit Leng
    ;
    Sriyana Abdullah
    Brazilian spinach is one of the best leafy vegetables with tons of nutrients and has a range of health benefits. Its quality also determines the acceptance of customers to buy and consume it. The common method to extend the shelf life of the spinach is through drying treatment and preserving the color and texture quality of the leaves. Therefore, this study aimed to determine the drying characteristics of Brazilian spinach and investigate the effect of drying temperature on the color and texture quality of Brazilian spinach. Brazilian spinach leaves were dried using a hot air dryer under different temperatures (30, 50, 70 and 90C). Results showed that the drying rate increased when temperature increased. It was found that the Midili model gave the best fitting to the experimental moisture ratio for a specific drying treatment. Drying the Brazilian spinach leaves at 50C was the best condition for preserving their color and texture properties.
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