3-Chlorotyrosine formation in gilthead seabream (Sparus aurata) and European plaice (Pleuronectes platessa) fillets treated with sodium hypochlorite

The chlorination of tyrosine in fish fillets as a result of hypochlorite dipping was investigated and the formation of 3-chlorotyrosine was proved to be reproducible (average RSD < 6.0%). In European plaice, 0.85% (inner portion) and 1.88% (surface) of tyrosine were converted to 3-chlorotyrosine after 60 min dipping in 2000 mg/L NaOCl. As the dose of hypochlorite acid increased to 7816 mg/L, those percentages were 1.07% and 2.81%, respectively. Experiments on gilthead seabream showed the clear impact of dipping time and NaOCl concentration on the formation of 3-chlorotyrosine at the fillet surface and the levels of 3-chlorotyrosine reached a plateau at 1000 mg NaOCl/L. At the same dipping time, the 3-chlorotyrosine contents increased noticeably from about 1.40 to 4.90 ppm in gilthead seabream fillets treated with 125–1000 mg/L NaOCl. 3-chlorotyrosine formation was evaluated in four fish species (whiting, European plaice, gilthead seabream and Atlantic salmon) and proved to be species dependent, but no direct with the fat content could be found. During the chilled storage (4 °C), the 3-chlorotyrosine was constant. The use of 31 mg OClˉ/L could be detected for seabream.     

Influence of pH and NaCl on monolaurin inactivation of Streptococcus iniae

Streptococcus iniae, a Gram-positive bacterium, has been recognized as a cause of human and fish streptococcosis. Aquacultured fish are susceptible to infection and have been epidemiologically linked with wound infections of fish handlers. Therefore, there is a need to develop methods of prevention and/or control of this pathogen. This study determined the minimum inhibitory concentration of monolaurin (glycerol monolaurate) against S. iniae strains PW and BU and utilized gradient plates at 37°C to determine the combined influence of pH and NaCl on monolaurin inactivation of S. iniae. The minimum inhibitory concentration of monolaurin against strain PW was 12.4±0.3 μg ml⁻¹ and against strain BU was 12.1±0 μg ml⁻¹. Compared to growth in the absence of monolaurin, the incorporation of 6 μg ml⁻¹ monolaurin into the salt (1.12–6.95%)–pH (4.26–8.88) gradient plates prevented growth of strain PW at pH values <6.00 and strain BU at pH values <6.20, regardless of the salt concentration. The combination of monolaurin with environmental variables such as pH and salt proved to be an effective tool for in vitro control of S. iniae.     

Effect of processing conditions on the structure of monostearin–oil–water gels

The effect of processing conditions on the formation and stability of a gel comprised of oil, water, monostearin and stearic acid was studied. Processing conditions (homogenization rate (10,000–30,000 rpm), cooling rate (0.05–20 °C/min), homogenization temperature (70–95 °C)) had no effect on the initial storage modulus and melting temperature of the gel. Salt (NaCl) addition to the aqueous phase in the range 0–0.25% did not affect these parameters either; however, 0.5% salt addition lead to a ∼2 °C decrease in melting temperature and a doubling of the storage modulus. Optimal preparation conditions for the gel were mainly determined from its microstructure by polarized light microscopy – a smaller globule size and a more homogenous size distribution were considered a desirable feature. Optimum conditions included homogenization rates greater than 20,000 rpm, cooling rates above 6 °C/min, homogenization temperatures above, but close to, the Krafft temperature of monostearin (72 °C), and 0% salt concentration. The gelation temperature decreased by 2 °C with each 1 °C/min increase in cooling rate, from 1 °C/min to 5 °C/min.     

Extraction of boldo (Peumus boldus M.) leaves with supercritical CO2 and hot pressurized water

High-activity fractions in boldo leaves were extracted with supercritical CO₂ (SC-CO₂) and hot pressurized water (HPW). Total yield after 3 h of extraction (0.6–3.5%) in low-pressure SC-CO₂ experiments increased with process pressure (60–150 bar) and decreased with temperature (30–60 °C), as expected. The extract obtained with SC-CO₂ at 50 °C and 90 bar contained approximately 50% of essential oil components. In higher pressure experiments with solvent mixtures, the yield increased with pressure (300–450 bar) and modifier concentration (2–10% ethanol), ranging 0.14–1.95 ppm for the alkaloid boldine and 1.8–4.8% for total solids following 1.5 h treatment at 50 °C. Boldine recovery was solubility-controlled, reaching 7.4 ppm after 7-h extraction at 450 bar and 50 °C using an ethanol–SC-CO₂ mixture (5% co-solvent). Boldine solubility and yield decreased when using pure CO₂ at higher pressure (600 bar, 50 °C). The extract yield after 3 h batch-wise HPW extraction increased from 36.9% at 100 °C to 53.2% at 125 °C, and then decreased as temperature was increased to 175 °C. Boldine yield decreased from 26.8 ppm at 100 °C to 0.7 ppm at 125 °C, and was negligible at ⩾150 °C. The essential oil yield increased to a maximum at 110 °C and was negligible at ⩾150 °C also. The ranking of antioxidant potency of various extracts was as follows: HPW at 110 °C > methanol (soxhlet extraction) ≫ high-pressure SC-CO₂ with or without polar co-solvent > low-pressure SC-CO₂.     

Temperature shows greater impact on bovine Longissimus dorsi muscle glycogen debranching enzyme activity than does salt concentration

The degradation of glycogen progresses by the co-operation of two enzymes: glycogen phosphorylase (phosphorylase) and glycogen debranching enzyme (GDE). We studied the effect of temperature (4–42 °C) and salt concentration (0–3% NaCl) on bovine M. longissimus dorsi GDE activity. GDE activity (n = 4) decreased significantly with decreasing temperature from about 40–4 °C. GDE exhibited 52% activity at 25 °C and 11% at 4 °C compared to its optimum activity measured at 39 °C. In rapidly chilled meat, the reduction in GDE activity may substantially delay the rate of glycolysis. However, residual GDE activity at 4 °C seems sufficient to enable the attainment of normal ultimate pH if the available time is long enough. An increase in salt concentration from 0% to 2% and to 3% induced a significant (P < 0.001) increase in the ultimate pH of ground bovine meat (n = 6), but showed no effect on GDE activity.     

Aluminium contents in baked meats wrapped in aluminium foil

In this investigation, the effect of cooking treatments (60 min at 150 °C, 40 min at 200 °C, and 20 min at 250 °C) on aluminium contents of meats (beef, water buffalo, mutton, chicken and turkey) baked in aluminium foil were evaluated. Cooking increased the aluminium concentration of both the white and red meats. The increase was 89–378% in red meats and 76–215% in poultry. The least increase (76–115%) was observed in the samples baked for 60 min at 150 °C, while the highest increase (153–378%) was in samples baked for 20 min at 250 °C. It was determined that the fat content of meat in addition to the cooking process affected the migration of aluminium (r² = 0.83; P < 0.01). It was also found that raw chicken and turkey breast meat contained higher amounts of aluminium than the raw chicken and turkey leg meat, respectively. Regarding the suggested provisional tolerable daily intake of 1 mg Al/kg body weight per day of the FAO/WHO Expert Committee on Food Additives, there are no evident risks to the health of the consumer from using aluminium foil to cook meats. However, eating meals prepared in aluminium foil may carry a risk to the health by adding to other aluminium sources.     

Spray chilling of deer carcasses—Effects on carcass weight,meat moisture content,purge and microbiological quality

Twenty red deer carcasses were included in the study. Two treatments were applied to the carcasses; control (air chilling) and spray chilling (n = 10 for each treatment). Carcass weight and temperature change were registered during over-night chilling. Meat moisture content was measured in the shoulder, loin, flap and leg before and after the chilling treatments; purge, cooking loss and tenderness were measured in loin samples stored at −1.5 °C for 3 and 9 weeks. Microbiological status was assessed on swabs taken at the lumbar end of the loin before and after the chilling treatments. Spray chilling reduced carcass weight loss significantly; air chilled and spray chilled carcasses lost 1 kg and less than 0.01 kg, respectively. No effects of spray chilling on tenderness, purge and cooking loss were found. Bacterial levels were low in general even after 9 weeks of vacuum packaged chilled storage.     

Characterization of amylase and protease produced by Aspergillus awamori in a single bioreactor

The aim of this study was to characterize the glucoamylase and acid protease produced in a single bioreactor by Aspergillus awamori: nakazawa MTCC 6652. Both the enzymes were found stable in wide range of pH (3–9) and temperature (25–70 °C). Optimum activities of amylase and protease were obtained at pH 4 and 5, respectively, whereas 70 and 55 °C had been found as most suitable temperature for highest activities of amylase and protease, respectively. Half life of glucoamylase was 210, 120, 60 and 35 min at 50, 60, 70 and 80 °C, respectively, which was 150, 120, 65 and 15 min at 40, 50, 60 and 70 °C, respectively, for acid protease. K_m and V_max of glucoamylase and protease were 9.8 mg/ml, 56.2 mg/ml/min and 1.08 mg/ml, 8.8 mg/ml/min, respectively. In low amount (1 mM) almost all metal ions except Mn, such as Ca²⁺, Co²⁺, Cu²⁺, Fe³⁺, Mg²⁺, Zn²⁺ and Hg²⁺ enhanced glucoamylase activity whereas protease activity was inhibited by all the ions except Zn²⁺. At low concentration, i.e., (0.03% w/v) Triton X-100 and SLS increased the activity of glucoamylase, while in higher concentration it inhibited activities of both the enzymes. β-mercaptoethanol at 0.25% (v/v) enhanced the amylase and protease activity by 1.6 and 3.0 fold, respectively, whereas the presence of 0.5% (v/v) β-mercaptoethanol inhibited the activities of both the enzymes drastically. At 0.5 M concentration of urea, glucoamylase activity increased but drastic inhibition took place at 5 M urea. In case of protease, 0.5 M of urea enhanced its activity and 1 M urea inhibited it completely. Thus, glucoamylase and protease produced by A. awamori nakazawa confirm their suitability for diverse applications in industries.     

Effect of very fast chilling and aging time on ultra-structure and meat quality characteristics of Chinese Yellow cattle M. Longissimus lumborum

Objectives of the current study were to evaluate meat ultra-structure and tenderness variation at different chilling regimes and aging times. Hot boned longissimus lumborum of 18 Chinese crossbred cattle were divided into 4 portions per side. One portion underwent very fast chilling (VFC, at − 21 °C to achieve core temperature of 0 °C, then transferred to another incubator at 2 °C), whereas other treatments were held at 14, 7 and 0 °C for 10 h postmortem, respectively. At 10 h postmortem, all muscles were vacuum aged at 2 °C for 21 d. Cold shortened muscles had greatest absolute amount of tenderization during aging. VFC caused lowest sarcomere length, with super-contractions, ruptured Z-lines and myofibril cleavage, but improved myofibril fragmentation index (MFI), with no significant negative effect on toughness. Overall, aging improved the meat quality of cold shortened beef. Moreover, it should be prudent in some applications to apply VFC to excised muscles from a food safety perspective, and to improve tenderness compared to cold-shortened muscles.     

Combined effect of ozonated water and chitosan on the shelf-life of Pacific oyster (Crassostrea gigas)

Effects of ozonated water and chitosan treatment on the shelf-life extension of Pacific oysters (Crassostrea gigas) stored at 5 ± 1 °C were studied. Results indicated that ozonated water treatment reduced the total microbial load of fresh oysters by about 10-fold (from 3.2 × 10³ CFU/g to 1.8 × 10² CFU/g) before storage and the microbial flora was different with that of raw samples. The wide-spectrum antibacterial property of chitosan against bacteria isolated from oysters was confirmed, and chitosan concentration of 5.0 g/l was eventually determined for application in oyster preservation. Based on microbiological analysis, biochemical indices determination and sensory evaluation, shelf-lives of 8–9 days for control, 10–12 days for ozonated water treated samples, 14–15 days for chitosan treated samples and 20–21 days for samples with combined treatment were observed, indicating that ozonated water and chitosan have a great potential for oyster preservation.Industrial relevanceAs seafood, Pacific oysters have a short shelf-life. Improvements in the shelf-life of oysters can have an important economic impact by reducing losses and by allowing the products to reach distant and new markets.In this work, Shelf-life of oysters with combined treatment of ozonated water and chitosan doubled, which has great practical meaning, and the process could be fully adopted by the food industry.We also did some research about the changes in microbial flora after ozonated water treatment. This work could help in preservation of oysters when ozone or ozonated water concerned.We discovered Wide-spectrum antibacterial property of chitosan against the strains isolated from raw oysters. The potential for using chitosan as a natural preservative in oysters was approved.     

Combinations of nisin with organic acids or salts to control Listeria monocytogenes on sliced pork bologna stored at 4°C in vacuum packages

This study evaluated dipping solutions of nisin with or without organic acids or salts, as inhibitors of Listeria monocytogenes introduced on sliced cooked pork bologna before vacuum packaging and storage at 4°C for 120 days. Inoculated (10²–10³ cfu/cm²) slices were immersed in nisin (5000 IU/ml), or in lactic or acetic acid (1, 3, 5 g/100 ml), sodium acetate or diacetate (3, 5 g/100 ml), and potassium benzoate or sorbate (3 g/100 ml), each combined with nisin. Additional slices were immersed in nisin, inoculated and then immersed in acid or salt solutions without nisin. Nisin reduced L. monocytogenes by 1.0–1.5 log cfu/cm² at treatment (day-0) followed by a listeriostatic effect for 10 days. Thereafter, however, the pathogen multiplied in treatments without acid or salts, with growth being faster on slices immersed in nisin after as compared to before inoculation. Nisin in combination with 3 or 5 g/100 ml acetic acid or sodium diacetate or 3 g/100 ml potassium benzoate, applied individually or as mixtures, did not permit growth before day-90. Other treatments were of variable and lesser effectiveness (20–70 days), whereas in untreated or water-treated (control) bologna L. monocytogenes increased at 6–7 log cfu/cm² at day-20. Based on the antilisterial efficacy and effects of treatments on product pH, nisin with 3 g/100 ml sodium diacetate may be the most promising combination in dipping solutions to control L. monocytogenes on sliced cured pork bologna.     

Changes in liking for a no added salt soup as a function of exposure

Multiple exposures have been shown to increase preference for novel foods or flavours. This “mere exposure” effect is also well known anecdotally for changes in preference for tastants within foods, for example reducing sugar in tea or coffee. However, to date, this phenomenon has received little scientific attention. The present study addressed this issue in relation to changes in preference for salt within soup. Following an initial assessment of liking, familiarity and saltiness of six soups varying in salt content (0–337 mg NaCl/ml), 37 participants, previously assessed for their preferred salt level in soup, were allocated to either an exposure group that received 20 ml soup samples with no added salt, to a group that received a 280 ml bowl of this soup, or to a control group that received 20 ml soup samples containing salt at 280 mg/100 g (within normal, commercial range). Soups were presented on eight occasions, at approximately daily intervals. The two groups receiving the no added salt soup showed increases in liking starting at the third exposure, and also evident in a repeat assessment following the exposures. Increases in familiarity of the no added salt soup were also evident during exposure. Rated saltiness of all soups increased as a function of exposure, so a change in saltiness perception could not account for changes in liking for just the no added salt soups. These data suggest that simple exposure to the taste of the no added salt soup was sufficient to increase liking to a level equivalent to the initially more preferred salt level.     

Comparison of properties of oil-in-water emulsions stabilized by coconut cream proteins with those stabilized by whey protein isolate

Coconut cream protein (CCP) fractions were isolated from coconuts using two different isolation procedures: isoelectric precipitation (CCP1-fraction) and freeze–thaw treatment (CCP2-fraction). The ability of these protein fractions to form and stabilize oil-in-water emulsions was compared with that of whey protein isolate (WPI). Protein solubility was a minimum at ∼pH 4, 4.5 and 5 for CCP1, CCP2, and WPI, respectively, and decreased with increasing salt concentration (0–200 mM NaCl) for the coconut proteins. All of the proteins studied were surface active, but WPI was more surface active than the two coconut cream proteins. The two coconut cream proteins were used to prepare 10 wt% corn oil-in-water emulsions (pH 6.2, 5 mM phosphate buffer). CCP2 emulsions had smaller mean droplet diameters (d₃₂ ≈ 2 μm) than CCP1 emulsions (d₃₂ ≈ 5 μm). Corn oil-in-water emulsions (10 wt%) stabilized by 0.2 wt% CCP2 and WPI were prepared with different pH values (3–8), salt concentrations (0–500 mM NaCl) and thermal treatments (50–90 °C for 30 min). Considerable droplet flocculation occurred in the emulsions near the isoelectric point of the proteins: CCP2 (pH ∼ 4.3); WPI (pH ∼ 4.8). Emulsions with monomodal particle size distributions, small mean droplet diameters, and good creaming stability could be produced at pH 7 for WPI, but CCP2 produced bimodal distributions at this pH. The CCP2 and WPI emulsions remained relatively stable to droplet aggregation and creaming at NaCl concentrations ⩽50 and ⩽100 mM, respectively. In the absence of salt, both CCP2 and WPI emulsions were quite stable to thermal treatments (50–90 °C for 30 min).     

Histamine accumulation and histamine-forming bacteria in Indian anchovy (Stolephorus indicus)

Accumulation of histamine, trimethylamine (TMA), and total volatile base nitrogen (TVB-N), as well as microbial population incidence in Indian anchovy (Stolephorus indicus) during storage in ice and at 15 and 35 °C were investigated. Histamine was as low as 1.9 mg/100 g in 15 days at ice storage, but it increased to 19.0 mg/100 g after 32 h at 15 °C. Histamine rapidly increased to 25.4 mg/100 g when stored at 35 °C for 8 h. TVB-N and TMA began to sharply increase after 11 days in ice storage, but abruptly increased after 16 and 8 h of storage at 15 and 35 °C, respectively. A high number of Enterobacteriaceae (10¹⁰–10¹¹ cfu/g) was detected and shown to be the dominant group of microbial flora during spoilage of Indian anchovy at both 15 and 35 °C. A total of 153 bacterial strains were selected from the prescreening step using various selective media. Only 75.8% of these selected isolates showed a positive reaction in Niven's differential medium, and 27.6% of the positive isolates were true histamine formers when confirmed by the enzymatic method. Prolific histamine formers were identified as Morganella morganii, Proteus vulgaris, and Enterobacter aerogenes, and produced high histamine content of 104.1–203.0 mg/100 ml. Optimum growth and histamine production of selected strains of these three species was at 35 °C in histamine evaluation broth (HEB) containing 0.5% NaCl, pH 5. E. aerogenes produced the highest histamine of 500 mg/100 ml at the optimum condition. All studied strains did not produce histamine at ⩾10% NaCl.     

Osmotic dehydration of carrot tissue enhanced by pulsed electric field,salt and centrifugal force

The osmotic dehydration (OD) kinetics of carrot disc untreated and treated by pulsed electric field (PEF) was studied under centrifugation (2400 × g), stirring (250 rpm) and with a salt addition (NaCl/sucrose solutions 0%/65%, 5%/60% and 15%/50%). The PEF intensity was E = 0.60 kV/cm and the treatment duration was t_PEF = 0.05 s (500 rectangular monopolar pulses each of 100 μs). The water loss (WL), solids gain (SG) and water loss/solids gain ratios (WL/SG) were evaluated in the binary (sucrose + water) and ternary (sucrose + salt + water) solutions at the temperature of 20 °C during 4 h. The mass ratio of sample to solution was 1:3. The PEF treatment and salt addition enhanced the OD kinetics. WL and SG were increased under centrifugation (centrifugal OD) and under stirring (static OD). The centrifugal field enhanced the WL, however, decreased the SG comparing to the static OD. Therefore, the static OD has advantages for the higher SG (confectionary adds), while the centrifugal OD is better appropriated if the WL should be increased and the solids (sugar) uptake should be limited (dietetic products).The two-exponential kinetic model fitted well to experimental data for both static and centrifugal OD. The correlation coefficient was R² = 0.982–0.999 and the standard error was 5–10%.     

Effects of drying methods and conditions on antimicrobial activity of edible chitosan films enriched with galangal extract

The aim of this work was to study the effects of drying methods and conditions (i.e., ambient drying, hot air drying at 40 °C, vacuum drying and low-pressure superheated steam drying within the temperature range of 70–90 °C at an absolute pressure of 10 kPa) as well as the concentration of galangal extract on the antimicrobial activity of edible chitosan films against Staphylococcus aureus. Galangal extract was added to the film forming solution as a natural antimicrobial agent in the concentration range of 0.3–0.9 g/100 g. Fourier transform infrared (FTIR) spectra and swelling of the films were also evaluated to investigate interaction between chitosan and the galangal extract. The antimicrobial activity of the films was evaluated by the disc diffusion and viable cell count method, while the morphology of bacteria treated with the antimicrobial films was observed via transmission electron microscopy (TEM). The antimicrobial activity, swelling and functional group interaction of the antimicrobial films were found to be affected by the drying methods and conditions as well as the concentration of the galangal extract. The electron microscopic observations revealed that cell wall and cell membrane of S. aureus treated by the antimicrobial films were significantly damaged.     

Mechanical and thermal characteristics of amaranth starch isolated by acid wet-milling procedure

Effects of soaking conditions during acid wet-milling of amaranth grain on mechanical and thermal properties of amaranth starch were investigated. A factorial design based on temperature (40–60 °C) and SO₂ concentration (0.1–1.0 g/L) was used. Dynamic oscillatory tests involved heating and cooling cycles (25–90 °C) with tempering at 90 °C followed by a frequency sweep (0.1–20 Hz) at constant temperature. Thermal properties of starch suspensions were based on DSC tests. Viscoelastic modulus and thermal properties were affected by both factors, being significant the interaction effect. Maximum values of viscoelastic modulus at the end of heating and cooling steps were determined for samples corresponding to soaking conditions of 50 °C and 1.0 g/L SO₂. Based on Ross-Murphy index from frequency sweep analysis it was found that paste behavior occurs at 60 °C and 0.1 g/L, while at 47.4 °C and 0.72 g/L starch suspension gave a strong gel. Onset (61.7 °C) and peak (66.2 °C) temperatures showed a minimum at 50 °C and 1.0 g/L. As SO₂ concentration decreased, the end of gelatinization took place at lower temperature. Maximum gelatinization enthalpy (12.7 J/g) was found at 40 °C and 0.1 g/L SO₂.     

Pressurized low polarity water extraction of lignans from whole flaxseed

The application of pressurized low polarity water (PLPW) extraction to the production of flaxseed lignans-rich products has been studied, and the key geometric and process conditions, including temperature, flow rate, and total volume have been determined and optimized. Maximum amounts of lignans and other flaxseed bioactive, including proteins were extracted at 160 °C and 5.2 MPa. However, on a dry weight basis the most concentrated extracts in terms of lignans and other phenolic compounds were obtained at 140 °C and 5.2 MPa. A flow rate of 0.5 mL/min was optimal for the extraction of lignans from flaxseed (Linum usitatissimum L.) and a total volume of 30–40 mL/g of seed was required to maximize the recovery. Higher flow rates increased the rate of the extraction but required larger water volumes. Bed depth to ID ratios of 5–18 resulted in faster extraction and maximum recovery (90–95%) at water to seed ratios of 30–50 mL/g. Larger depth to ID ratios (15–18) would allow the use of lower solvent to solid ratios (14–20 mL/g) and would still result in yields of 84–90%.     

Lactic acid fermentation of onions

Lactic acid fermentation was conducted on sweet, white, and yellow storage onions to produce souronion. The onions were sliced to 0.3 cm thick, salt was added at 1.5, 2.0, and 2.5 g/100 g without or with sugar at 1.0 and 2.0 g/100 g, and the fermentation temperature was 18°C. Since onions do not have the necessary lactic acid bacteria for the anaerobic fermentation, onions were inoculated using either brine from sauerkraut or slices of cabbage. The fermentation produced souronion with pH between 3.25–3.35 and 1.2–1.5 g lactic acid/100 ml, which is in the range as that of sauerkraut. Sensory evaluation showed that the yellow storage souronion was a favorable product with respect to color, texture and flavor. The souronion had a tart acidic taste, characteristic of sauerkraut, with onion flavor but without the pungency of raw onions.     

Thermal and dielectric properties of shucked oysters

Thermal conductivity, thermal diffusivity and specific heat were measured for shucked oysters. Thermal conductivity increased from 0.577 to 0.677 W/m °C as temperature increased from 0 to 50 °C measured by a line heat source thermal conductivity probe. Specific heat was measured using a differential scanning calorimeter. It increased from 3.795 to 4.047 kJ/kg °C when temperature was raised from 10 to 50 °C. Thermal diffusivity of oysters was calculated from thermal conductivity, specific heat and density values. Dielectric properties of oysters were determined by an open-ended coaxial cable connected to a network analyser between 300 MHz and 3 GHz. At microwave frequencies of 915 and 2450 MHz, it was observed that the dielectric constant decreased (64.02–50.89 at 915 MHz and 59.10–47.67 at 2450 MHz), while the loss factor increased (13.84–20.14) at 915 MHz as temperature increased from 1 to 55 °C. Models were developed to describe the temperature effects on thermal and dielectric properties of shucked oysters.