Evaluation of environmental performance of dietary patterns in the United States considering food nutrition and satiety.

Food production substantially depletes the environment in different ways, but little is known about how overall dietary patterns relate to these environmental impacts. The objective of this study was to evaluate the environmental performance of different dietary patterns among U.S. adults using life cycle assessment (LCA). A "typical" dietary pattern was compared with those recommended by the Dietary Guidelines for Americans, including "healthy U.S.", Mediterranean and lacto-ovo vegetarian. Supplemental functional units (FUs) were applied to incorporate the functions of food to provide nutrition and satiety, namely Nutrient Rich Foods Index 9.3 (NRF9.3), Nutritional Quality Index (NQI), and Fullness Factor™ (FF). Life cycle inventory data was collected for 14 food categories consisting of 76 component foods, and their midpoint environmental impacts were calculated, with particular focus on global warming potential. Diets in accordance with different patterns were constructed from selected component foods at a reference energy amount of 2000 kcal. Vegetarian diets on average generated the lowest carbon footprint regardless of the FU. However, large possible variations in the environmental profiles of the compared diets were identified due to the wide range of food choices within a pattern, which showed highly different nutrition and satiety scores even within the same food category. Animal products, including meat and dairy especially, and discretionary foods were identified as the specific food categories that contributed the most to the global warming potential. Discretionary foods consistently exhibited higher impacts on the basis of nutritional FUs due to their low nutrient density. The results can be implied as practical guidelines to help reduce the carbon footprint associated with current U.S. diets without compromising their nutritional adequacy and satiety.

Effect of crosslinking on the physical and chemical properties of ß-lactoglobulin (Blg) microgels.

HYPOTHESIS: Microgels assembled from the protein ß-lactoglobulin are colloidal structures with potential applications in food materials. Modifying the internal crosslinking within these microgels using enzymatic or chemical treatments should affect dissolution, swelling, and viscous attributes under strongly solvating conditions. EXPERIMENTS: Microgels were treated with citric acid, glutaraldehyde and transglutaminase to induce cross-linking or with tris(2-carboxyethyl)phosphine to reduce disulfide linkages. Change in hydrodynamic particle size due to acidic pH, alkaline pH, ionic strength, osmolyte concentration, ethanol, urea, sodium dodecyl sulfate, and reducing agents was evaluated by light scattering measurements. Changes in microgel nanomechanical properties were evaluated via force spectroscopic measurements in water. FINDINGS: Average microgel size increased ∼20% in alkaline pH and with ethanol contents above 10%, and decreased ∼20% with sucrose contents above 10%. Cross-linking by glutaraldehyde and transglutaminase prevented size increases in alkaline pH. Microgel plasticity and elastic modulus were unaffected by treatments. Microgels treated with glutaraldehyde were found to have much greater stability to urea, sodium dodecyl sulfate, and reducing agents when compared to other samples. Even without cross-linking, microgels remained stable against precipitation and dissolution over a wide range conditions, indicating their broad utility as colloidal stabilizers, texture modifiers or controlled release agents in food or other applications.

Effect of high-pressure processing of bovine colostrum on immunoglobulin G concentration, pathogens, viscosity, and transfer of passive immunity to calves.

This study aimed to determine the effects of high-pressure processing on the immunoglobulin concentration, microbial load, viscosity, and transfer of passive immunity to calves when applied to bovine colostrum as an alternative to thermal pasteurization. A pilot study using Staphylococcus aureus was conducted to determine which pressure-time treatments are most appropriate for use with bovine colostrum, with the goals of maximizing bacterial inactivation while minimizing IgG content and viscosity changes. Following the pilot study, an inoculation study was conducted in which first-milking colostrum samples from Holstein-Friesian cows were inoculated with known concentrations of various bacteria or viruses and pressure processed at either 300 MPa for up to 60min or at 400MPa for up to 30min. The recovery of total native aerobic bacteria, Escherichia coli, Salmonella enterica ssp. enterica serovar Dublin, Mycobacterium avium ssp. paratuberculosis, bovine herpesvirus type 1, and feline calicivirus were determined after processing. Colostrum IgG content was measured before and after pressure processing. Shear stress and viscosity for each treatment was determined over shear rates encompassing those found during calf feeding and at normal bovine body temperature (37.8°C). Following a calf trial, serum IgG concentration was measured in 14 calves fed 4 L of colostrum pressure processed at 400MPa for 15min. In the pilot study, S. aureus was effectively reduced with pressure treatment at 300 and 400MPa (0, 5, 10, 15, 30, and 45min), with 2 treatments at 400MPa (30, 45min) determined to be inappropriate for use with bovine colostrum due to viscosity and IgG changes. High-pressure processing at 300MPa (30, 45, and 60min) and 400MPa (10, 15, and 20min) was shown to effectively reduce total native aerobic bacteria, E. coli, Salmonella Dublin, bovine herpesvirus type 1, and feline calicivirus populations in bovine colostrum, but no decrease occurred in Mycobacterium avium ssp. paratuberculosis. All inoculation study pressure treatments insignificantly decreased IgG content of colostrum. Treatment of colostrum at 400MPa for 15min during the calf trial decreased IgG content of colostrum. Treatment at 400MPa for 15min increased colostrum viscosity, with 2 of 14 samples requiring dilution with water for calf feeding. Calves fed pressure-processed colostrum had similar serum IgG but lower efficiency of absorption than calves fed heat-treated colostrum. The results of this study suggest that high-pressure processing of bovine colostrum maintains an acceptable IgG level while decreasing bacterial and viral counts. Changes in viscosity sometimes made calf feeding more difficult, but still feasible. Additional research to optimize this technology for on-farm use is necessary.

Dynamic and viscoelastic interfacial behavior of ß-lactoglobulin microgels of varying sizes at fluid interfaces.

HYPOTHESIS: Microgel particles formed from the whey protein ß-lactoglobulin are able to stabilize emulsion and foam interfaces, yet their interfacial properties have not been fully characterized. Smaller microgels are expected to adsorb to and deform at the interface more rapidly, facilitating the development of highly elastic interfaces. METHODS: Microgels were produced by thermal treatment under controlled pH conditions. Dynamic surface pressure and dilatational interfacial rheometry measurements were performed on heptane-water droplets to examine microgel interfacial adsorption and behavior. Langmuir compression and atomic force microscopy were used to examine the changes in microgel and monolayer characteristics during adsorption and equilibration. FINDINGS: Microgel interfacial adsorption was influenced by bulk concentration and particle size, with smaller particles adsorbing faster. Microgel-stabilized interfaces were dominantly elastic, and elasticity increased more rapidly when smaller microgels were employed as stabilizers. Interfacial compression increased surface pressure but not elasticity, possibly due to mechanical disruption of inter-particle interactions. Monolayer images showed the presence of small aggregates, suggesting that microgel structure can be disrupted at low interfacial loadings. The ability of ß-lactoglobulin microgels to form highly elastic interfacial layers may enable improvements in the colloidal stability of food, pharmaceutical and cosmetic products in addition to applications in controlled release and flavor delivery systems.

Control of thermal fabrication and size of ß-lactoglobulin-based microgels and their potential applications.

HYPOTHESIS: Factors influencing fabrication and size of microgels formed from ß-lactoglobulin with or without pectin can tune selected attributes for material applications. Protein aggregation was expected to be influenced by pH, added anions, and reducing agents, while ionic strength was expected to be more influenced by electrostatically interacting pectin. EXPERIMENTS: Turbidity measurements during thermal aggregation to form microgels were determined for pure ß-lactoglobulin as a function of pH, added ionic strength, anion type (chloride, sulfate, and thiocyanate), and reducing agent concentration. ß-lactoglobulin and pectin complexation pH values and thermal aggregation were determined by turbidity measurements with added potassium chloride, sulfate, and thiocyanate. Microgel size and morphology were determined by light scattering and atomic force microscopy, respectively. FINDINGS: Thermal aggregation of pure ß-lactoglobulin increased with decreased pH, reducing conditions, and increased ionic strength with no observed anion effect. ß-lactoglobulin microgel radii increased from 86 to 115nm with decreasing pH and increased to 124nm in reducing conditions, while salts promoted agglomeration. Increased ionic strength (0-100mmol/kg) decreased ß-lactoglobulin-pectin complexation pH from 5.40 to 5.00, while first increasing and then decreasing thermal aggregation. Thermal aggregation and microgel size were greatest with potassium thiocyanate, followed by potassium chloride and potassium sulfate.

The effect of acidification of liquid whey protein concentrate on the flavor of spray-dried powder.

Off-flavors in whey protein negatively influence consumer acceptance of whey protein ingredient applications. Clear acidic beverages are a common application of whey protein, and recent studies have demonstrated that beverage processing steps, including acidification, enhance off-flavor production from whey protein. The objective of this study was to determine the effect of preacidification of liquid ultrafiltered whey protein concentrate (WPC) before spray drying on flavor of dried WPC. Two experiments were performed to achieve the objective. In both experiments, Cheddar cheese whey was manufactured, fat-separated, pasteurized, bleached (250 mg/kg of hydrogen peroxide), and ultrafiltered (UF) to obtain liquid WPC that was 13% solids (wt/wt) and 80% protein on a solids basis. In experiment 1, the liquid retentate was then acidified using a blend of phosphoric and citric acids to the following pH values: no acidification (control; pH 6.5), pH 5.5, or pH 3.5. The UF permeate was used to normalize the protein concentration of each treatment. The retentates were then spray dried. In experiment 2, 150 µg/kg of deuterated hexanal (D12-hexanal) was added to each treatment, followed by acidification and spray drying. Both experiments were replicated 3 times. Flavor properties of the spray-dried WPC were evaluated by sensory and instrumental analyses in experiment 1 and by instrumental analysis in experiment 2. Preacidification to pH 3.5 resulted in decreased cardboard flavor and aroma intensities and an increase in soapy flavor, with decreased concentrations of hexanal, heptanal, nonanal, decanal, dimethyl disulfide, and dimethyl trisulfide compared with spray drying at pH 6.5 or 5.5. Adjustment to pH 5.5 before spray drying increased cabbage flavor and increased concentrations of nonanal at evaluation pH values of 3.5 and 5.5 and dimethyl trisulfide at all evaluation pH values. In general, the flavor effects of preacidification were consistent regardless of the pH to which the solutions were adjusted after spray drying. Preacidification to pH 3.5 increased recovery of D12-hexanal in liquid WPC and decreased recovery of D12-hexanal in the resulting powder when evaluated at pH 6.5 or 5.5. These results demonstrate that acidification of liquid WPC80 to pH 3.5 before spray drying decreases off-flavors in spray-dried WPC and suggest that the mechanism for off-flavor reduction is the decreased protein interactions with volatile compounds at low pH in liquid WPC or the increased interactions between protein and volatile compounds in the resulting powder.

The effect of feed solids concentration and inlet temperature on the flavor of spray dried whey protein concentrate.

Previous research has demonstrated that unit operations in whey protein manufacture promote off-flavor production in whey protein. The objective of this study was to determine the effects of feed solids concentration in liquid retentate and spray drier inlet temperature on the flavor of dried whey protein concentrate (WPC). Cheddar cheese whey was manufactured, fat-separated, pasteurized, bleached (250 ppm hydrogen peroxide), and ultrafiltered (UF) to obtain WPC80 retentate (25% solids, wt/wt). The liquid retentate was then diluted with deionized water to the following solids concentrations: 25%, 18%, and 10%. Each of the treatments was then spray dried at the following temperatures: 180 °C, 200 °C, and 220 °C. The experiment was replicated 3 times. Flavor of the WPC80 was evaluated by sensory and instrumental analyses. Particle size and surface free fat were also analyzed. Both main effects (solids concentration and inlet temperature) and interactions were investigated. WPC80 spray dried at 10% feed solids concentration had increased surface free fat, increased intensities of overall aroma, cabbage and cardboard flavors and increased concentrations of pentanal, hexanal, heptanal, decanal, (E)2-decenal, DMTS, DMDS, and 2,4-decadienal (P < 0.05) compared to WPC80 spray dried at 25% feed solids. Product spray dried at lower inlet temperature also had increased surface free fat and increased intensity of cardboard flavor and increased concentrations of pentanal, (Z)4-heptenal, nonanal, decanal, 2,4-nonadienal, 2,4-decadienal, and 2- and 3-methyl butanal (P < 0.05) compared to product spray dried at higher inlet temperature. Particle size was higher for powders from increased feed solids concentration and increased inlet temperature (P < 0.05). An increase in feed solids concentration in the liquid retentate and inlet temperature within the parameters evaluated decreased off-flavor intensity in the resulting WPC80.

Impact of infrared finishing on the mechanical and sensorial properties of wheat donuts.

UNLABELLED: Infrared radiation may be used to simulate an immersion frying heat flux and create products with fried-like textures but lower fat contents. The objective of this study was to determine the process parameters needed to produce partially-fried, infrared-finished donuts comparable to fully-fried (control) donuts. A total of 8 different sets of infrared oven parameters (emitter height and belt speed) were tested. Instrumental analysis showed that all infrared-finished donuts had significantly (P ≤ 0.05) lower fat content (25.6% to 30.6%) than the control (33.7%). Setting the infrared emitters in a height gradient from 70 to 50 mm or at a constant height of 60 mm above the belt produced donuts that were most instrumentally similar to the control. Infrared-finished donuts had comparable (P ≤ 0.05) overall acceptance scores to the control, 5.28 to 5.85 versus 5.83, respectively. Infrared radiation may be used to finish-fry partially-fried donuts, yielding a product similar to a fully-fried donut but with significantly lower fat content. PRACTICAL APPLICATIONS: The partial-frying, infrared-finishing process detailed in this article may be used for other deep-fried foods. It is likely that these foods will also have a lower fat content when prepared with this process than when they are deep-fried. This process provides a method of lowering the fat content of fried foods without changing the food formulation.