Optimisation of the microencapsulation conditions and physicochemical properties of enteric‐coated lactase microcapsules

Enteric double‐coated lactase microcapsules were developed, and the encapsulation conditions were optimised using response surface methodology. The optimum concentration of the enteric coating material was 4.85 g/100 mL, and the amount of core material was 1.85 mL. The particle size of the zein‐coated microcapsules was 2.868 μm, which was smaller than that of the other microcapsules. All microcapsules showed high zeta‐potential values between pH 6 and 8. The in vitro release rates of hydroxypropyl methyl cellulose phthalate (HPMCP)‐ and shellac‐coated microcapsules were superior to that of the zein‐coated microcapsules. Finally, the microcapsules were barely hydrolysed in simulated gastric fluid; however, almost all the microcapsules coated with HPMCP or shellac released their contents in simulated intestinal fluid within 2 h (93.23 and 97.27%, respectively).     

Functional and Thermal Properties of Wheat, Barley, and Soy Flours and Their Blends Treated with a Microbial Transglutaminase

The effects of transglutaminase (TG) on the functional and thermal properties of wheat, barley, and soy flours and their blends were investigated. Free amino and thiol groups and aromatic hydrophobicity in samples were decreased with TG treatment (P < 0.05), confirming the polymerization of proteins in flours by TG treatment. TG‐treated samples had increased water‐holding capacity, fat adsorption, and emulsion stability, and slightly decreased emulsion activity. The addition of barley or soy to wheat flours decreased fat adsorption and emulsion stability, but these values increased, upon TG treatment of the same blended samples, to levels as high as for untreated wheat alone. TG treatment did not significantly affect the transition peak temperature of the flour samples. However, TG treatment lowered the transition enthalpy of wheat blended with barley or soy flour, and, conversely, increased that of wheat flour samples alone. Results suggest that protein cross‐linking by TG can produce unique and improved functionality even in wheat blended with barley or soy flour, and could provide opportunities for exploitation of this enzyme for product development.     

Coastal water quality impact of stormwater runoff from an urban watershed in southern California

Field studies were conducted to assess the coastal water quality impact of stormwater runoff from the Santa Ana River, which drains a large urban watershed located in southern California. Stormwater runoff from the river leads to very poor surf zone water quality, with fecal indicator bacteria concentrations exceeding California ocean bathing water standards by up to 500%. However, cross-shore currents (e.g., rip cells) dilute contaminated surf zone water with cleaner water from offshore, such that surf zone contamination is generally confined to < 5 km around the river outlet. Offshore of the surf zone, stormwater runoff ejected from the mouth of the river spreads out over a very large area, in some cases exceeding 100 km2 on the basis of satellite observations. Fecal indicator bacteria concentrations in these large stormwater plumes generally do not exceed California ocean bathing water standards, even in cases where offshore samples test positive for human pathogenic viruses (human adenoviruses and enteroviruses) and fecal indicator viruses (F+ coliphage). Multiple lines of evidence indicate that bacteria and viruses in the offshore stormwater plumes are either associated with relatively small particles (< 53 microm) or not particle-associated. Collectively, these results demonstrate that stormwater runoff from the Santa Ana River negatively impacts coastal water quality, both in the surf zone and offshore. However, the extent of this impact, and its human health significance, is influenced by numerous factors, including prevailing ocean currents, within-plume processing of particles and pathogens, and the timing, magnitude, and nature of runoff discharged from river outlets over the course of a storm.     

The onset of natural convection in a horizontal fluid layer heated isothermally from below

The onset of buoyancy-driven convection in an initially quiescent fluid layer confined between two horizontal plates is analyzed theoretically. In case of isothermal heating it is well known that convective motion sets in when the Rayleigh number Ra exceeds 1708. For Ra > 1708, there are three characteristic times t_c, t_D and t_u which represent respectively, the critical time to mark the onset of intrinsic instability, the detection time of motion, and the undershoot time in a plot of the heating rate versus time. These characteristic times are analyzed by employing the numerical method under the single mode of instabilities and fitting some experimental t_u-values. The new measures to represent t_c and t_D are suggested, based on the growth rates of fluctuations. It is interesting that t_c is the invariant but the predicted t_D- and t_u-values are dependent upon the magnitude of initial conditions forced. It is shown that for the isothermally heated system of a large Prandtl number the relation of t_u ? 7t_c agrees well with the available experimental t_u-values for Ra > 10⁵ and t_D is located between t_c and t_u. This paper removes the confusion among the characteristic times, t_c, t_D and t_u in the literature on stability. Also the boundary-layer instability model is discussed in order to analyze turbulent thermal convection heat transfer characteristics in the fully developed state, based on the present numerical predictions.     

Effects of plant extracts on microbial growth, color change, and lipid oxidation in cooked beef

The effects of butylated hydroxyanisole/butylated hydroxytoluene (BHA/BHT), grape seed extract (ActiVin), pine bark extract (Pycnogenol), and oleoresin rosemary (Herbalox) on microbial growth, color change, and lipid oxidation were investigated in cooked ground beef. When compared to the control, 1.0% ActiVin and Pycnogenol) effectively reduced the numbers of Escherichia coli O157:H7 and Salmonella Typhimurium, and retarded the growth of Listeria monocytogenes and Aeromonas hydrophila. Pycnogenol resulted in reductions of 1.7, 2.0, 0.8, and 0.4 log CFU/g, respectively, in numbers of E. coli O157:H7, L. monocytogenes, S. Typhimurium, and A. hydrophila, respectively, after 9 days of refrigerated storage. The color of cooked beef treated with ActiVin was less light (L*), more red (a*), and less yellow (b*) than those treated with BHA/BHT, Pycnogenol, and Herbalox. ActiVin and Pycnogenol effectively retained the redness in cooked beef during storage. The control showed significantly higher thiobarbituric acid-reactive substances (TBARS) and hexanal content over storage. BHA/BHT, ActiVin, Pycnogenol, and Herbalox retarded the formation of TBARS by 75%, 92%, 94%, and 92%, respectively, after 9 days, and significantly lowered the hexanal content throughout the storage period. Results of this work show that ActiVin and Pycnogenol are promising additives for maintaining the quality and safety of cooked beef.     

Effects of vegetable juice powder concentration and storage time on some chemical and sensory quality attributes of uncured, emulsified cooked sausages

ABSTRACT:  Uncured, no-nitrate/nitrite-added meat products can be manufactured with vegetable juice powder (VJP) and a starter culture containing Staphylococcus carnosus , resulting in quality and sensory attributes similar to traditional cured products. The 1st objective of this study was to determine the effects of varying concentrations of VJP and incubation times (MIN-HOLD) on quality characteristics, including lipid oxidation, color, and cured meat pigment concentrations, of emulsified-frankfurter-style-cooked (EFSC) sausages over a 90-d storage period. The 2nd objective was to compare residual nitrate and nitrite content resulting from different processing treatments and the 3rd objective was to assess sensory properties of finished products. Four EFSC sausage treatments (TRT) (TRT 1: 0.20% VJP, 30 MIN-HOLD; TRT 2: 0.20% VJP, 120 MIN-HOLD; TRT 3: 0.40% VJP, 30 MIN-HOLD; TRT 4: 0.40% VJP, 120 MIN-HOLD) and a sodium nitrite-added control (C) were used for this study. No differences for lipid oxidation (TBARS) between any TRTs and C or over time were observed. No differences ( P > 0.05) for CIE L * values were found between TRTs. CIE a * and reflectance ratio values revealed that TRTs 2, 4, and C were redder than TRTs 1 and 3 at day 0. Trained sensory intensity ratings for cured aroma, cured color, cured flavor, uniform color, and firmness determined that all but TRT 1 were similar to C. These results indicate a longer incubation time (120 compared with 30 min) was found more critical than VJP level (0.20% or 0.40%) to result in products comparable to a sodium nitrite-added control.     

Pd–Cu alloy membrane deposited on CeO2 modified porous nickel support for hydrogen separation

In this study, the hydrogen permeation behavior of a Pd₉₃–Cu₇ alloy membrane deposited on ceria-modified porous nickel support (PNS) was evaluated. PNS, which has an average pore size of 600 nm, was modified by alumina sol. Alumina sol was prepared using precursors that had a mean particle size of 300 nm. Alumina-modified PNS was further treated with ceria sol modification to produce a smoother surface morphology and narrow surface pores. A 7 μm thick Pd₉₃–Cu₇ alloy membrane was made on an alumina-modified PNS and a ceria-finished membrane was fabricated by magnetron sputtering followed by Cu-reflow at 700 °C for 2 h. SEM analysis showed that the membrane deposited on a ceria-finished PNS contained more clear grain boundaries than the membrane deposited on the alumina-modified PNS. The membrane was mounted in a stainless steel permeation cell with a gold-plated stainless steel O-ring. Permeation tests were then conducted using pure hydrogen and helium at temperatures ranging from 673 to 773 K and feed side pressures ranging from 100 to 400 kPa. These tests showed that the membrane had a hydrogen permeation flux of 2.8 × 10⁻¹ mol m⁻² s⁻¹ with H₂/He selectivity of >50,000 at a temperature of 773 K and pressure difference of 400 kPa.     

Characteristics of biohydrogen fermentation from various substrates

The characteristics of biohydrogen production from sucrose, slurry-type piggery waste and food waste under the effects of the reactor configurations and operational pHs (6 and 9) were examined by using heat-treated anaerobic sludge as a seed biomass. When sucrose was used in the batch test, the maximum hydrogen yield was 0.12–0.13 g COD (as H₂)/g COD (1.41–1.43 mol/mol hexose) at pH 6. In contrast, 0.10–0.11 g COD (as H₂)/g COD (1.12–1.21 mol/mol hexose) hydrogen yield was achieved from the reactor at pH 9. On the other hand, hydrogen production was not observed in the continuous sequencing batch mode fermenters fed with sucrose. Profile analysis at each cycle revealed hydrogen production at the initial operation periods but eventually only methane at 36 days. When slurry-type piggery waste was used as the substrate, the upflow elutriation-type fermenters produced methane but not hydrogen after 30 days operation. The fermentation intermediate profile showed that the hydrogen produced might have been consumed by homoacetogenic or propionate producing reactions, and eventually converted into methane by acetoclastic methanogens. The downflow leaching bed fermenters using food waste produced 0.013 L H₂/g volatile solids (VS) (0.0061 g COD (as H₂)/g COD) at pH 6 with 54% VS reduction whereas 0.0041 L H₂/g VS (0.0020 g COD (as H₂)/g COD) was produced at pH 9 with 86% VS reduction. The results show that the hydrogen produced should be released rapidly from the reactor before it can be consumed in other biochemical reactions, and substrates with high pH level (>9.0) can be used directly to produce hydrogen without needing to adjust the pH.     

Improving functional value of meat products

In recent years, much attention has been paid to develop meat and meat products with physiological functions to promote health conditions and prevent the risk of diseases. This review focuses on strategies to improve the functional value of meat and meat products. Value improvement can be realized by adding functional compounds including conjugated linoneleic acid, vitamin E, n3 fatty acids and selenium in animal diets to improve animal production, carcass composition and fresh meat quality. In addition, functional ingredients such as vegetable proteins, dietary fibers, herbs and spices, and lactic acid bacteria can be directly incorporated into meat products during processing to improve their functional value for consumers. Functional compounds, especially peptides, can also be generated from meat and meat products during processing such as fermentation, curing and aging, and enzymatic hydrolysis. This review further discusses the current status, consumer acceptance, and market for functional foods from the global viewpoints. Future prospects for functional meat and meat products are also discussed.     

Factors in Various Fractions of Meat Homogenates That Affect the Oxidative Stability of Raw Chicken Breast and Beef Loin

ABSTRACT:  The fractions of meat homogenates were analyzed to find the factors that determine the susceptibility of raw chicken breast and beef loin to lipid oxidation. The fractions used in this study were meat homogenate, precipitate, and supernatant of homogenate after centrifugation, and high and low molecular weight fractions from the supernatant. Chicken breast showed greater oxidative stability than beef loin during 10-d storage ( P < 0.05). All fractions from chicken breast showed lower amounts of free ionic iron and myoglobin and higher total antioxidant capacity (TAC) than those from beef loin during storage. The TAC level of chicken breast maintained during storage. This suggested that the oxidative stability of chicken breast was ascribed to high, stable total antioxidant capacity with low level of catalysts for lipid oxidation. The water-soluble high molecular weight fraction, which contained myoglobin, was responsible for the high lipoxygenase-like activity and lipid oxidation potential (LOP) in beef loin. TAC in all fractions from beef loin decreased during storage. This suggested that high myoglobin content in beef loin caused the imbalance between pro- and antioxidant factors leading to the high susceptibility of beef loin to lipid oxidation. Myoglobin served a major source of catalysts, ferrylmyoglobin, hematin, and/or free ionic iron, for lipid oxidation.