UPV External Publications
Permanent URI for this communityhttps://hdl.handle.net/20.500.14583/14
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Item Development of a Facile and Convenient Method for Sugar Determination in Low Moisture Confectioneries and Honeys Using Fourier Transform Infrared Attenuated Total Reflectance Spectroscopy and ChemometricsSetijadi, Catherine H.; Felix, Jonathan N.; Ellis, Helena C.; Alumbro, Jihan Santanina S.; Bello, Ghalib; Dumancas, Gerard G. (Informa UK Limited, 2020-01-10)A method using Fourier transform infrared with attenuated total reflectance spectroscopy and partial least squares (PLS) chemometric analysis to simultaneously quantify the mass percent concentrations of glucose, fructose, and sucrose, commonly found in honey and low moisture confectionery food products, was developed. A three-component full factorial design was generated as a training set (n = 64) to predict the sugar concentrations in a Box-Behnken testing set (n = 16). Analysis of the entire spectral region from 649.99 to 3996.38 cm−1 using Savitzky–Golay signal processing technique and PLS algorithm garnered optimal errors of prediction and better linearity between predicted and measured concentrations in the test set compared to analysis using a specific spectral region from 800 to 1500 cm−1 and using a wide array of signal processing techniques (first derivative, second derivative, moving average, binning, and standard normal variate). The model further detected these sugar concentrations in 3 standard honeys, 12 commercial honey samples, 8 honey adulterants, 13 low moisture confectionery food samples, and 15 unknown honey samples from Louisiana apiaries. Applying principal component and clustering analysis also enabled the discrimination of these honey samples based on their fructose:glucose ratios. Thus, the developed method represents a potentially novel, simple, accurate, nondestructive, and rapid means of quantifying concentrations of glucose, fructose, and sucrose in honey and low-moisture confectioneries in 1–2 minutes.Item Effects of light quality and temperature on the photosynthesis and pigment content of a subtidal edible red alga Meristotheca papulosa (Solieriaceae, Gigartinales) from JapanBorlongan, Iris Ann; Suzuki, Sayuri; Nishihara, Gregory N.; Kozono, Jumpei; Terada, Ryuta (Springer Science and Business Media LLC, 2020-02-11)This study investigated the effects of different light spectral qualities and temperature on the photosynthesis and pigment content of a subtidal edible red alga, Meristotheca papulosa. Photosynthesis–irradiance (P–E) experiments were carried out under red (660 nm), blue (450 nm), green (525 nm, light-emitting diodes), and white light (visible light, metal halide lamp), and at 12, 20, and 28 °C, respectively. Maximum net photosynthetic rates (NPmax) were highest under green light. Other P–E parameter estimates were similar among algae under red, blue, and green light, including their lower initial slope (α) and higher saturation irradiances (Ek) as compared to those under white light. Additionally, NPmax and Ek under white light were highest at 28 °C, and lowest at 12 °C, with characteristic photoinhibition at irradiances greater than 150 μmol photons m−2 s−1. Photosynthesis–temperature (P–T) experiment revealed that the maximum gross photosynthetic rate (GPmax) occurred at 22.1 °C, which was within the optimal temperature range of Fv/Fm (21.5–23.6 °C). Exposures to the different light qualities at 100 μmol photons m−2 s−1 for 7 days showed increased phycoerythrin (PE) concentration of algae under blue and green light, while chlorophyll-a and phycocyanin (PC) showed little variation in all light qualities. Therefore, considering future management prospects for M. papulosa mariculture, we suggest that green light could be utilized to enhance photosynthesis. Furthermore, if the aim is to achieve high PE content for an improved reddish-color fresh product, exposure to blue or green light could be a good alternative.Item Microbiological Quality and Heavy Metal Concentrations in Slipper Oyster (Crassostrea iredalei) Cultured in Major Growing Areas in Capiz Province, Western Visayas, Philippines: Compliance with International Shellfish Safety and Sanitation StandardsPakingking, Rolando; Hualde, Lilibeth; Peralta, Ernestina; Faisan, Joseph; Usero, Roselyn (International Association for Food Protection, 2022)The increasing demand for slipper oyster (Crassostrea iredalei) has propelled farmers to expand oyster cultivation areas in the Philippines, chiefly for local consumption and feasibly for export overseas. As filter feeders, oysters can accumulate pathogens from the surrounding waters, and these pathogens can cause foodborne diseases in consumers. Therefore, oyster farming areas must be monitored for microbiological quality and heavy metal concentrations. In the present study, the microbiological quality of oysters and their growing waters in the major oyster farming areas of the Cogon and Palina Rivers and Cabugao Bay (in Roxas City and the Municipality of Ivisan, respectively, Capiz Province, Western Visayas, Philippines) were examined monthly during the wet (May to October) and dry (November to April) seasons over 12 months. Regardless of the sampling period, high levels of fecal coliforms in the water and Escherichia coli in oysters were found, clearly illustrating that these oyster growing areas would meet only the class B standard under the European Union classification system and would be considered “prohibited” for growing oysters under the U.S. classification system. Although Salmonella was occasionally detected in oysters, Vibrio cholerae was not detected and Vibrio parahaemolyticus was within acceptable limits. The heavy metal concentrations in oyster meat were also determined during the wet (July) and dry (March) seasons. Zinc and copper were the most abundant metals detected, and concentrations of lead, cadmium, mercury, and chromium were below the regulatory limits set by the European Union and the U.S. Food and Drug Administration. These oyster culture areas should be rehabilitated immediately to improve the microbiological quality of the oysters. Oysters harvested from these sites must be depurated or relayed to ensure quality and safety. Copyright ©, International Association for Food ProtectionItem Comparative biochemical characterization of pufferfish saxitoxin and tetrodotoxin-binding protein (PSTBP) homologs in the plasma from four Takifugu species: Conservation of heat-stable PSTBP orthologs having three and two tandemly repeated lipocalin domains in genus TakifuguZhang, Yafei; Ueno, Mikinori; Tatsuno, Ryohei; Takatani, Tomohiro; Shimasaki, Yohei; Arima, Kazunari; Sedanza, Mary Grace; Yamaguchi, Kenichi; Oshima, Yuji; Arakawa, Osamu (Elsevier, 2025)To study the relationship between domain characteristics of pufferfish saxitoxin and tetrodotoxin binding protein (PSTBP) proteoforms and their thermal stability, a comparative biochemical characterization of PSTBPs from the plasma of four Takifugu species (T. flavipterus, T. pardalis, T. alboplumbeus and T. rubripes) was conducted by Western blot analysis. The heat-tolerance tetrodotoxin (TTX)-binding ability of PSTBP proteoforms in T. rubripes plasma was verified by ultrafiltration and liquid chromatography tandem mass spectrometry (LC-MS/MS). These results suggest that the heat-stable PSTBP proteoforms, composed of three and two tandemly repeated lipocalin domains, are genetically conserved and ubiquitous in the genus Takifugu. This study builds on our knowledge of the structural and functional properties of PSTBP proteoforms, which is vital for understanding how toxins are transmitted and accumulate in organisms and is essential for evaluating the potential risks of toxins in seafood.Item Structural, electronic, and optical properties of copper doped monolayer molybdenum disulfide: A density functional theory studyDucut, Melsa Rose D.; Rojas, Kurt Irvin M.; Bautista, Reilly V.; Arboleda, Nelson B. Jr. (Elsevier, 2025)We conducted first-principles calculations to investigate the effect of doping monolayer molybdenum disulfide (MoS2) with Cu in its structural, electronic, and optical properties. We found that Cu doping changes the material from an n-type semiconductor into a p-type semiconductor by shifting the Fermi energy level towards the valence band in all variations of concentration and site. The absorption coefficient, photoconductivity, and reflectivity calculations indicate that Cu-doped MoS2 is sensitive to violet light. In addition, Cu doping elevates the sensitivity of the material to low-energy light. These results show that Cu-doped MoS2 can be used in optoelectronic applications.