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Author: search.filters.author.Kerr, William L.Has files: No

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    Impact of roasting levels and brewing cycles on bioactive compounds in spent coffee grounds
    (2026-02-01)
    Maiyah, Nur
    ;
    Kerdpiboon, Soraya
    ;
    Kerr, William L.
    ;
    Klaypradit, Wanwimol
    ;
    Smithisukul, Chayada
    Spent coffee grounds (SCGs) represent a potential source of residual bioactive compounds for sustainable reuse. Effects of roasting levels and sequential brewing cycles on recovery of total phenolic content (TPC), total flavonoid content (TFC), caffeine, and chlorogenic acid (CGA) from Arabica and Robusta SCGs were investigated. Coffee beans were roasted (light, medium, dark), brewed through three hydrothermal cycles, and the resulting SCGs extracted with 70% ethanol. The first brewing cycle removed most water-soluble bioactive compounds, while subsequent brews induced smaller compositional changes, indicating the persistence of functional compounds. Roasting influenced the initial bioactive profile, but its impact diminished after brewing. Robusta SCGs retained higher TPC and antioxidant activity while caffeine diminished with brewing cycle, they were relatively stable to roasting while CGA was more heat-sensitive. Principal component analysis confirmed brewing history as the main factor governing SCG chemical profiles. These findings support brewing-informed SCG valorization for sustainable functional food applications.
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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
    ;
    Kerdpiboon, Soraya
    ;
    Supapvanich, Suriyan
    ;
    Kerr, William L.
    ;
    Sriprom, Pongsert
    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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    Drying effects on physicochemical and functional properties of cuttlefish (Sepia officinalis) ink powder
    (2024-09-01)
    Salsabila, Salma
    ;
    Kerdpiboon, Soraya
    ;
    Kerr, William L.
    ;
    Puttongsiri, Tongchai
    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.
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    Novel sous-vide pressure technique affecting properties of local beef muscle
    (2023-02-01)
    Chotigavin, Natthaporn
    ;
    Kerr, William L.
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    Klaypradit, Wanwimol
    ;
    Kerdpiboon, Soraya
    The low-temperature, long-time method of cooking known as sous-vide was used with increased pressure to enhance the tenderness and cook yield of local Thai beef round. The cooking was done in specialized equipment at 60 °C and 101, 200 or 300 kPa for 0–4 h. Beef treated with pressure was slightly lighter in color, and samples cooked for 2 h at 200 kPa had greater red saturation. Cooking at 200 kPa improved cook yield while reducing cook loss, with values of 78% after 4 h at 200–300 kPa versus 67% at 101 kPa. Cooking at 200–300 kPa resulted in more tender beef than at 101 kPa after 2 h. Sensory evaluation showed sous-vide pressure beef had higher ranking scores for tenderness and juiciness compared to control. SEM showed connective tissue of sous-vide pressure-cooked beef was diffuse and with looser muscle fibers than boiled or raw beef. Electrophoretic profiles showed that thick and thin filament bands decreased with cooking time. However, myosin heavy chain was sensitive to both heat and pressure. Reducing conditions showed pressure and heat induced disulfide bonding. Studies by FTIR showed cooking at 200 kPa caused the greatest decrease in α-helix content and increase in β-structures than non-treated and boiled beef.
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    Sous-vide meat properties as a function of physical and surface changes during processing
    (2022-01-01)
    Chotigavin, Natthaporn
    ;
    Kerr, William L.
    ;
    Klaypradit, Wanwimol
    ;
    Kerdpiboon, Soraya
    Sous-vide is a method of cooking of vacuum-packed samples at relatively low temperature for longer periods than practiced with conventional cooking. Sous-vide is applicable to a wide variety of foods, and optimized sous-vide processing of meat can result in more tender products with less cooking loss. In this study, chicken breast and Thai local beef round were compared under sous-vide (vacuum-packaged and cooked at 60 to 80 °C for 1 to 7.5 h) and traditional cooking temperatures. The physical properties and surface texture of meat during sous-vide cooking were determined. It was found that the L<sup>*</sup> (lightness) and a<sup>*</sup> (redness) of cooked chicken breast were not affected by cooking temperatures or times (p >0.05), while the color of cooked beef depended on both temperature and time (p ≤0.05). It was found that cooking at higher temperature and for longer time resulted in meat with lower cooking yield and higher sous-vide loss, but with less re-heating loss (p ≤0.05). These results were supplemented with surface texture images which showed that larger spaces developed between the fibers after cooking at higher temperatures for longer time than those for samples cooked by sous-vide. Sous-vide chicken breast cooked at 60 °C for 2 h and 80 °C for 0.5 h, as well as beef cooked at 60 °C for 2.5 h and 80 °C for 2 h, were the most tender as measured by the lowest shear force values.