Comparative Studies on the Physicochemical Properties and Hydration Behavior of Oat Gum and Oatrim in Meat-based Patties

ABSTRACT: Goat/rabbit meat patties were formulated using oatrim (0.5,1.0,2.0, %) and oat gum (0.5,1.0, and 2%). Patties were evaluated for sensory attributes, nutrient content and hydration behavior. Moisture content decreased with increased oatrim and oat gum addition. Protein content of patties containing 2% oatrim slightly increased. However, ash values were lower than control. Shear force values were higher for oatrim containing patties than for oat gum. Patties containing oatrim and oat gum received favorable responses for acceptability. NMR spin-spin (T₂) and spin-lattice (T₁) relaxation times were generally higher in oat gum patties than oatrim. Generally, T₁ and T₂ decreased with added oat gum or oatrim and increased with increased temperature.     

Molecular Dynamics of Soy-Protein Isolate Films Plasticized by Water and Glycerol

ABSTRACT: The effects of water and glycerol on the molecular mobility of a soy-protein isolate (SPI)-based film were investigated using ¹H nuclear magnetic resonance (NMR). SPI-films were prepared with different glycerol contents and equilibrated to various levels of water activity (a_w). The distributed transverse relaxation of film samples showed 2 distinct components: a solid-like fraction (T_2s*) and a liquid-like fraction (T_2m*). The peak T_2s* values of films with lower glycerol concentration were more sensitive to variation in a_w. As a_w increased, the change of solid-like to liquid-like fraction was observed in higher glycerol films. As glycerol content increased, a minimum longitudinal relaxation time (T₁) occurred at lower a_w. Our results suggest that NMR techniques can be used to quantify the plasticizing effects on biopolymer films.     

Use of Artificial Neural Network to Predict Temperature, Moisture, and Fat in Slab-Shaped Foods with Edible Coatings During Deep-Fat Frying

ABSTRACT: An artificial neural network (ANN) was developed to predict heat and mass transfer during deep-fat frying of infinite slab-shaped foods coated with edible films. Frying time, slab half-thickness, film thickness, food initial temperature, oil temperature, moisture diffusivity of food and film, fat diffusivity through food and film, thermal diffusivity of food, heat transfer coefficient, initial moisture content of food, and initial fat content of food (mf_o) were inputs. Temperature at the center (T₁), average temperature (T_ave), fat content (mf_ave), and moisture content (m_ave) of food were outputs. Four ANNs with 50 nodes each in 2 hidden layers with learning rate = 0.7 and momentum = 0.7 provided most accurate outputs, that is maximum absolute errors for T₁ and T_ave were < 1.2 °C, < 0.004 db for m_ave, and < 0.003 db for mf_ave. The predictions of mf varied linearly with mf.     

Study of Caking in Powdered Foods Using Nuclear Magnetic Resonance Spectroscopy

Twenty-three powdered foods and ingredients were subjected to 2 treatments: temperature scan from -20 to 110 °C within 2 hours, and storage at 37 °C and 55 °C for 60 d. During temperature scans, the spin-spin relaxation time T₂ values of individual samples were determined using a nuclear magnetic resonance (NMR) technique, resulting in a temperature-T₂ curve for each sample. Four typical temperature-T₂ curve patterns were identified and were found to be closely related to the physical changes in the samples, including agglomeration, water vaporization, and caking observed during temperature scans. Based on the temperature-T₂ curve patterns, the samples were classified into 4 groups each having distinguished caking behavior. In the storage tests, the samples were removed from the incubators every half an hour during first 2 d of storage period and every day afterwards. The storage test also suggests a strong relationship between molecular mobility and caking. Monitoring changes in T₂ as a function of temperature provides information useful for predicting whether and when caking would occur.     

Artificial neural network modeling for temperature and moisture content prediction in tomato slices undergoing microwave-vacuum drying

ABSTRACT:  Inputs for ANN (multihidden-layer feed-forward artificial neural network) models were drying time ( t _{i + 1}), initial temperature ( T ₀), moisture content ( MC ₀), microwave power, and vacuum pressure. The outputs were temperature ( T _{i + 1}) and moisture content ( MC _{i + 1}) at a given t _{i + 1}. After training the ANN models with experimental data using the Levenberg-Marquardt algorithm, a two-hidden-layer model (25-25) was determined to be the most appropriate model. The mean relative error (MRE) and mean absolute error (MAE) of this model for T _{i + 1} were 1.53% and 0.77 °C, respectively. In the case of MC _{i + 1}, the MRE and MAE were 11.48% and 0.04 kg_water/kg_dry, respectively. Using temperature ( T _i ) and moisture content ( MC _i ) values at t _i in the input layer significantly reduced the computation errors such that MRE and MAE for T _{i + 1} were 0.35% and 0.18 °C, respectively. In contrast, these error values for MC _{i + 1} were 1.78% (MRE) and 0.01 kg_water/kg_dry (MAE). These results indicate that ANN models were able to recognize relationships between process parameters and product conditions. The model may provide information regarding microwave power and vacuum pressure to prevent thermal damage and improve drying efficiencies.     

STRESS RELAXATION AND TENSILE STRENGTH TESTING OF A PROCESSED FISH PRODUCT

Minced silvercarp was prepared as cooked loaves containing only various added salts. The loaves were then subjected to stress-relaxation and tensile strength tests. The various treatments gave different compression forces, relaxation T_50% values and tensile strengths. The compression force measurements were closely correlated with tensile strength values. Both compression force and tensile strength might be related to the binding quality (cohesiveness) of the loaves. The relaxation T_50% values were not closely correlated with the compression forces nor the tensile strengths, and might be related to the product's viscoelastic properties. Different percent deformation did not have a significant effect on the relative order of the compression force values, but did affect the relaxation T_50% values, with larger differences between samples at 25% deformation.     

EFFECT OF MODIFIED ATMOSPHERE PACKAGING ON THE QUALITY OF SMOKED CATFISH

Smoked catfish were inoculated with Listeria ivanovii then packaged under 80% CO₂/20% N₂ (M₁) and 40% CO₂/30%O₂/130% N₂ (M₂) and stored at 2 and 8C. Noninoculated samples packaged under air (A) served as controls. Fillets stored under M₂ at 8C showed the fastest growth of L. ivanovii. L. ivanovii counts in samples stored under M₁ at both temperatures decreased significantly over time. Listeria growth was observed in samples stored under air at 2 and 8C after 2 weeks. APC results were similar to that of Listeria The highest TBA values were observed in M₂-stored samples followed by air-stored samples. Lightness ("L" values) increased significantly, whereas "a" (redgreen) and "b" (blue/yellow) values decreased in all atmospheres at both temperatures over time. The combined use of M₁ and 2C improved the quality of smoked catfish by inhibiting microbial growth and minimizing the extent of lipid oxidation.     

RHEOLOGICAL BEHAVIOUR OF SHEARED JAMS. RELATION WITH FRUIT CONTENT

Eight samples of jam were sheared to destroy gel structure and their flow behaviour was analysed in a concentric cylinder viscometer. Jams were prepared from 4 different fruits—strawberry, peach, plum, and apricot—at 50% and 30% fruit content approximately. Flow of sheared jam showed time dependence, which could be quantified by the Weltmann model and which was eliminated by shearing samples for 8 min at 300 rpm. Casson's yield stress values were obtained at two ranges of shear rates: 0.08–1.01 s⁻¹ (O₀₁) and 2.58–387.30 s⁻¹ (o₀₂). o₀₂ values were about double the o₀₁ values. Flow was adequately described by the Herschel and Bulkley model, introducing either of the yield stress values (o₀₁ or o₀₂). Significant differences were found for some of the rheological parameters studied (Weltmann A and B constants, o₀₁, o₀₂, K₁, and n₁) between samples containing 50% and 30% fruit. These results demonstrate the role played by fruit particles in the rheological behaviour of this type of product and suggest the possibility of using rheological parameters as indices of fruit content in jams.     

DYNAMIC MECHANICAL ANALYSIS OF MARINATED CHICKEN BREAST MEAT

Chicken breast muscle was marinated and tumbled in solutions of 7% NaCl and 1.2% of disodium pyrophosphate (DSPP), tetrasodium pyrophosphate (TSPP), tetrapotassium pyrophosphate (TKPP), sodium tripolyphosphate (STPP), or glass phosphate. Dynamic mechanical thermal analysis was used to measure storage modulus and Tan δ as samples were heated from 25 to 75C. For untreated samples, four thermal transitions were noted with the most significant transition at 55.8C. Addition of NaCl and phosphate reduced the number of distinct events, and decreased the major transition to temperatures around 46–48C. Uncooked, marinated samples had lower G' and Tan δ. Treated samples also showed an increase in G' over the 25–45C range. Heating caused the greatest changes in treated samples, with values of G'_75C and Tan δ_75C similar to untreated samples. Different phosphate types resulted in significant differences in G' and Tan δ values. G' values correlated well with Young's modulus, but not with Warner-Bratzler shear values or expressible moisture. Results are discussed in terms of changes in muscle proteins resulting from exposure to NaCl and phosphates, as well as to heat.     

Changes in the free -NH2, free -CO2H and titratable acidity of meat proteins

The 2, 4, 6-trinitrobenzene sulphonic acid (TNBS) spectrophotometric assay and formol titration were used to measure changes in free -NH₂ and free -CO₂H respectively, in meat proteins dissolved in 3% sodium dodecyl sulphate (SDS). Changes in the titratable acidity of the meats was also determined. The free -NH₂ groups were found to decrease markedly with cooking while -CO₂H remained relatively constant. Intermediate moisture beef ( Longissimus dorsi ) processed and stored at 38°C showed the free groups increasing for up to 8 weeks' storage due to proteolysis, followed later by a sharp fall due to cross-linking. But titratable acidity of the IM beef samples continued to rise with storage.     

Interaction of ultraviolet light, chemicals and cultured mammalian cells: photobiological reactions of halogenated antiseptics, drugs and dyes

We have successfully demonstrated that cells in culture are sensitive to damage produced by a variety of phototoxic agents. Differences in the apparent sensitivity of the three cell systems employed (photohaemolysis, phototoxicity to macrophages and to Chinese hamster CHV79 cells) have been exploited to reflect the mechanism of action of the phototoxic materials. Overall four distinct patterns of phototoxic response were observed which indicate specific sites of action of the phototoxic materials within the cell. Of the two halogenated antiseptics tested 3,3',4',5-tetrachlorosalicylanilide (T₄CS) was phototoxic and 3,4,4'-trichlorocarbanilide (TCC) was not; of the drugs both 8-methoxypsoralen (8-MOP) and chlorpromazine (CP) were phototoxic; and of the three dyes rose bengal (RB) and Blankophor (FB) were phototoxic and Tinapol (EMS) was not. Phototoxic cellular damage produced by CP, RB and FB could be totally prevented by continuous gassing with O₂-free, 5% CO₂ in N₂. T₄CS and 8-MOP phototoxic cellular damage was found to proceed independently of the presence or absence of O₂.     

CALCIUM CHLORIDE EFFECTS ON TBA VALUES OF COOKED MEAT

Ground chicken breast and beef top round (semimembranosus) muscles were treated with CaCl₂ (0.05, 0.10, 0.15, and 0.20% on final sample weight basis) and cooked to an internal temperature of 80C. Cooked samples were aerobically stored at 4C for 0 or 4 days and analyzed for 2-thiobarbituric acid (TBA)-reactive substances. Results indicated that CaCl₂ can either inhibit or accelerate lipid oxidation in cooked meat depending on its concentration/meat animal species. TBA values of chicken samples were decreased by CaCl₂ used at ≥ 0.1% of final weight. However, only beef samples treated with the highest CaCl₂ level (0.20%) tended to have lower TBA values when compared to control samples (treated with deionized water only). CaCl₂ used at low levels (0.05% for chicken and ≤0.15% for beef) tended to elevate cooked meat TBA values.     

Preparation and Characterization of Whey Protein Film Incorporated with TiO2 Nanoparticles

ABSTRACT:  Biodegradable titanium dioxide (TiO₂)/whey protein isolate (WPI) blend films were made by casting denatured WPI film solutions incorporated with TiO₂ nanoparticles. X-ray diffraction, UV-vis spectra, and fluorescence spectra of the films showed the successful incorporation of TiO₂ nanoparticles into the WPI matrix and indicated the interactions between TiO₂ and WPI. Mechanical tests revealed the antiplasticizing effect of TiO₂ nanoparticles on the WPI/TiO₂ film. Small amounts (<1 wt%) of added TiO₂ nanoparticles significantly increase the tensile properties of WPI film, but also decrease the moisture barrier properties. The addition of higher amounts (>1 wt%) of TiO₂ improves moisture barrier properties but lowers the tensile properties of the film. Microstructural evaluation confirmed the aggregation and distribution of TiO₂ nanoparticles within the WPI matrix and validated the results of functional properties of the WPI/TiO₂ film.     

Characteristics and Use of Yellow Stripe Trevally Hydrolysate as Culture Media

ABSTRACT:  Characteristics and the use as culture media of protein hydrolysate from yellow stripe trevally (HF₂₅) were determined in comparison with Bacto Peptone. HF₂₅ had the higher contents of ash (45.73%), lipid (0.77%), and moisture (4.34%) but lower protein content (42.11%) than did Bacto Peptone ( P  < 0.05). HF₂₅ powder was slightly darker than Bacto Peptone ( P  < 0.05). HF₂₅ contained a higher amount of essential amino acids (44.05%) than did Bacto Peptone (19.34%). HF₂₅ and Bacto Peptone consisted of several minerals at varying levels and had an excellent solubility over a wide pH range. At water activity (a_w) greater than 0.75, the much higher moisture sorption was found in HF₂₅ ( P  < 0.05). HF₂₅ showed the higher bacterial productivity ratio than did Bacto Peptone ( P  < 0.05). When HF₂₅ and commercial Bacto Peptone were used as microbial media to determine microbial load of environmental and food samples and pathogenic bacteria, HF₂₅ generally exhibited similar potential in culturing those microorganisms ( P  > 0.05). Thus, the conversion of low market value species to fish protein hydrolysate, which can be used as the nitrogenous substrate for microbial growth, could be achieved.     

EFFECT OF FISH PROTEIN, SALT, SUGAR, AND MONOSODIUM GLUTAMATE ON THE GELATINIZATION OF STARCH IN FISH-STARCH MIXTURES

Differential Scanning calorimetry (DSC) was used to study the effect of fish protein, salt, sugar, and monosodium glutamate (MSG) on gelatinization of tapioca and sago starches in fish cracker mixtures. One endothermic transition was observed for fish-starch mixtures (10–90% wet fish) if the moisture content was more than 61%. The effect of the salt on the starch gelatinization is greater than sugar and MSG. Sugar and MSG addition to the mixture had little effect on gelatinization of starch in the system. Two percent salt increased the gelatinization temperature by 4–5 C. The onset (T₀) and peak (T_p) temperatures increased with increases in fish content in fish-starch mixtures but the conclusion temperatures (T_c) remained relatively constant. Increases in fish content also narrowed the gelatinization temperature ranges.     

RHEOLOGICAL INDICES OF FRUIT CONTENT IN JAMS: EFFECT OF FORMULATION ON FLOW PLASTICITY OF SHEARED STRAWBERRY AND PEACH JAMS

The effect of formulation factors on Casson yield values measured at low shear rates (0.08 ≤γ≤ 1.01s^-1) (σ₀₁) and at medium shear rates (2.58 ≤γ≤ 387.30s^-1) (σ₀₂) was analyzed in previously sheared strawberry and peach jams. Twenty three samples of each fruit jam were prepared according to a second order composite rotatable design. Composition ranges were: fruit content, 25–55%; soluble solids content, 60–70° Brix; added pectin in strawberry jams, 0.3–0.7% and in peach jams, 0.1–0.5%. Variation of σ₀₁ values in strawberry jams depended mainly on the interactions between fruit and soluble solids and between fruit and pectin, while in peach jams, it depended on fruit-soluble solids and soluble solids-pectin interactions. Patterns of change of σ₀₂ values with composition were similar to those observed for σ₀₁ in both strawberry and peach jams. Predictive power of σ₀₁ and σ₀₂ values for estimation of fruit content was low, but taken in conjunction with soluble solids content and total pectin values, 79.5% of the variability of fruit content in strawberry jams and 91.1% of same in peach jams could be explained.     

Detection of aflatoxin M1 in milk and dairy products consumed in Adana, Turkey

A total of 70 dairy products consisting of 20 sterilized milk, 10 butter, 20 white cheese and 20 Kashar cheese samples were analysed for aflatoxin M₁ (AFM₁) by enzyme-linked immunosorbent assay (ELISA). The detection limit was 5 ng/L for milk and 25 ng/kg for butter, white cheese and Kashar cheese. Of the 70 dairy products analysed, AFM₁ in 49 samples (70%) was found to range from 10 to 388 ng/kg. Moreover, AFM₁ levels in three samples of milk, two samples of butter, one sample of white cheese and one sample of Kashar cheese were found to be higher than the Turkish legal limits.     

A FRACTURE MECHANICS ANALYSIS OF THE TEXTURE OF POTATOES

The generalized fracture mechanics approach (GFM) developed by Andrews (1974) was applied to measure the fracture toughness of potatoes of the cultivar Shepody . Specimens were fashioned from the centre portions of 10 tubers, and were soaked in distilled water overnight to attain full turgor pressure in the cells. Tensile tests were performed on specimens with different initial crack lengths. The function k₁(W₀) for potatoes was evaluated. This function is an explicit distribution function of input energy in the specimen (work done on unit volume of the specimen). From the form of the function, a simple mathematical model was developed to describe k₁(W₀) for potatoes. The critical apparent energy release rate defined by GFM theory was found to be constant ( T = 2650 J m⁻²) and independent of initial crack length and applied load. The fracture toughness ( T₀ ) of Shepody potato obtained from this value of T was 212 J m⁻², which is in good agreement with the results of other researchers using uniaxial compressive and tensile tests.     

Stability of pectins during storage

Low methoxyl pectins (LMP) prepared by HCl, NaOH and NH₃ deesterification procedures were stored with or without adding Na₂CO₃ as buffer at room temperature (25–30°C) or exposed to different relative humidities (r.h.) at 37°C. Losses of methoxyl, molecular weight and gelling power were observed in all the pectin samples. During storage, NaOH and NH₃ deesterified LMP were more stable than HCl deesterified LMP with respect to gelling power. The monolayer values ( V _m) of 0.5 to 0.7 g per 100 g of LMP showed that even when stored at 11% r.h., the moisture in LMP was present in the multilayer region which was conducive to methoxyl loss.
NH₃ deesterified LMP precipitated at pH 0.5 and 1.5 after saponification, formed good gels similar to the LMP precipitated at pH 0.5, dried and mixed with buffer. NH₃ deesterified LMP precipitated at pH 3.0 and 4.5, on the contrary, formed only coagulated gels.
The loss of gelling power of LMP during storage was due to depolymerization besides gradual transformation of increasing portions of pectinic acid molecules into pectic acid molecules. High methoxyl pectins with or without added sodium carbonate or citrate as buffer stored at 62 and 75% r.h. showed methoxyl loss. Between r.h. of < 0.1 and 49%, methoxyl loss was more in the buffered samples than in the control.     

Quality changes during refrigerated storage of MA-packaged pre-rigor fillets of farmed Atlantic cod (Gadus morhua L.) using traditional MAP, CO2 emitter, and vacuum

ABSTRACT:  Quality changes during 3 wk of refrigerated storage (1.3 °C) were studied on pre -rigor filleted farmed Atlantic cod packed in modified atmosphere (MAP, 60% CO₂ and 40% O₂) or vacuum. The packages of MAP contained either a CO₂ emitter and low gas volume to product volume (g/p ratio) of 1.3, or a 3.9 g/p ratio and no emitter. The CO₂ level remained stable or increased in the packages with CO₂ emitter, whereas the CO₂ level in the packages with no CO₂ emitter decreased to 40% after 4 d of refrigerated storage. High levels of oxygen in the gas mixture prevented formation of trimethyl amine (TMA) during storage of the MA-packed fish, whereas the TMA content increased significantly after 10-d storage in vacuum. MA-packed samples had the highest values of 1-penten-3-ol. Sensory scores of sour, sulfur, and pungent odors were significantly higher for vacuum-packed cod compared to the 2 MA-packaging methods measured 14 d after slaughtering. No differences in sensory scores were observed between the 2 methods of MAP, and shelf life of these samples seemed to be 14 to 21 d. Cod samples packaged in vacuum packages had higher pH values compared to ordinary MAP and packages containing a CO₂ emitter. Bacterial growth was inhibited by MAP and resulted at the end of the storage period in dominance of Carnobacterium and some Photobacterium . In MA packages with high O₂ levels the Photobacterium was inhibited. It is concluded that CO₂ emitters are well suited for reduction of transport volume for MA-packaged farmed cod.