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    Recovering bioactive compounds and antioxidant capacity of medium roasted spent coffee grounds through varied hydrothermal brewing cycles
    (2025-04-01)
    Maiyah, Nur
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    Kerr, William L.
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    Spent coffee grounds (SCGs) are the residual product from brewing coffee and contain valuable bioactive compounds. This study investigated the effects of hydrothermal brewing cycles on the bioactive compounds and antioxidant capacity of medium roasted Arabica (A) and Robusta (R) SCGs. SCGs from A and R were prepared using 3 levels of brewing cycles at 92–95 °C/900 kPa. The SCGs were collected and air dried at 60 °C to achieve a moisture content of less than 4 % wb. Field emission scanning electron microscopy (FE-SEM) imaging showed that brewing increased SCGs porosity, allowing more moisture retention and enhanced extraction of compounds on subsequent cycles. SCGs also became less pigmented after additional brewing. Fourier-transform infrared (FTIR) spectra confirmed the retention of chemical components after each cycle, indicating a level of stability in the functional groups. Ethanol extraction yielded higher total phenolic content (TPC), while water extraction resulted in greater total flavonoid content (TFC); however, both decreased with additional hydrothermal brewing cycles. Caffeine and chlorogenic acid were more abundant in ethanol extracts, whereas water extracts exhibited stronger antioxidant activity (measured by ABTS and FRAP), particularly in Robusta SCGs. The bioactive compounds and antioxidant capacity were reduced with additional SCGs brewing. Significant correlations between TPC, TFC, caffeine, and antioxidant measures underscore the potential for the sustainable reuse of SCGs as a bioactive resource. Overall, hydrothermal brewing cycles enhanced the extraction and utilization of bioactive compounds from SCGs, contributing to the development of value-added products that promote health and sustainability.
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    Item type:Publication,
    Drying effects on physicochemical and functional properties of cuttlefish (Sepia officinalis) ink powder
    (2024-09-01)
    Salsabila, Salma
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    Kerr, William L.
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    This study investigated the physicochemical, functional, and organoleptic properties of cuttlefish (Sepia officinalis) ink powder prepared by freeze drying and hot air tray drying. Key proximate and physicochemical properties were measured to assess differences due to drying method. In addition, organoleptic tests were conducted on cuttlefish ink powder incorporated into spaghetti sauce. Freeze-dried powders had slightly higher moisture (9.86 %) than tray-dried powders (7.65 %) and more ash (15.04 versus 13.19 %). Both samples had ∼43 % protein, a light-brown to black color and a pH of 5.5–5.6 when rehydrated. There were no differences in loose or tapped density and Hausner ratios of 1.30–1.35 suggest the powders had ‘passable’ flow. Overall protein solubility varied with pH and freeze-dried materials generally had greater solubility. FT-IR showed no differences in peaks derived from organic components. FE-SEM showed both samples had spherical granules that formed 100–200 nm clusters; however, the surface texture of tray-dried powders was rougher than the freeze-dried samples. Consumer tests showed higher overall likability for spaghetti sauce with fresh ink compared to dried ink powders. Differences were attributed more to texture than to flavor or appearance. Cuttlefish ink can be utilized in the food industry, particularly as a natural flavor, food coloring or additive.