Helen S. Joyner

Impact of Formulation and Saliva on Acid Milk Gel Friction Behavior

UNLABELLED Rheological analysis is commonly used to evaluate mechanical properties in studies of food behavior. However, rheological analysis is often insufficient to describe food texture as evaluated by descriptive sensory analysis. Additionally, traditional rheometry does not account for changes in food behavior as a function of saliva incorporation into the food during mastication. The objectives of this study were to evaluate friction behavior of acid milk gels with and without the addition of saliva, and to determine relationships between frictional behaviors and mechanical and sensory behaviors. Acid milk gels were prepared with 12.5% total solids comprising nonfat dry milk, whey protein isolate, waxy maize starch, and gelatin in different ratios. The addition of starch was found to have significant impact on acid milk gel frictional behavior. Addition of saliva resulted in a change in frictional behavior over the entire sliding speed range measured. Correlations were found between rheological, tribological, and sensory behavior, suggesting that an underlying mechanism may impact both viscosity and friction behavior. Additional study is needed to further explore the links between food structure, rheology, tribology, and sensory texture. PRACTICAL APPLICATION Application of tribology in food science allows measurement of friction behavior of foods. Matching both rheological and tribological behavior is important to creating reduced-fat or reduced-sugar products with similar mouthfeel to the original product.

Impact of Oil-in-Water Emulsion Composition and Preparation Method on Emulsion Physical Properties and Friction Behaviors

Emulsions have been used as a model food system for many studies on food behavior, including tribological studies. Several studies have examined the effect of fat content and emulsifier on emulsion friction behavior; however, other emulsion parameters such as ionic strength, pH, and homogenization pressure have received little attention in the literature. Additionally, emulsion friction measurements are generally compared to sensory data rather than physical property data. Thus, the objective of this study was to investigate the effect of various emulsion parameters on emulsion physical properties and rheological and friction behavior. Emulsion salt content, pH, and homogenization pressure all affected friction behavior, with specific effects dependent on the emulsifying protein. All emulsions showed reduced friction coefficient with increased fat content. Emulsion rheological behavior was not strongly impacted by changes in the emulsion parameters. Changing emulsion pH had the strongest effect on emulsion physical properties. The results of this study suggest that tribology may be used to develop a “fingerprint” for emulsions prepared using different parameters, allowing improved differentiation of these emulsions compared to traditional rheometry.

Microwave Pasteurization of Cooked Pasta: Effect of Process Parameters on Texture and Quality for Heat-and-Eat and Ready-to-Eat Meals.

Pasta presents a challenge to microwave processing due to its unique cooking requirements. The objective of this study was to determine the effects of microwave processing on pasta physicochemical and mechanical properties. Fettuccine pasta was parboiled for selected times, then pasteurized using a Microwave Assisted Pasteurization System and stored under refrigeration for 1 wk. Samples were analyzed using microscopy, mechanical testing, and chemical analyses after storage. While no significant differences were observed for free amylose among fresh samples, samples parboiled for ≤6 min had significantly higher free amylose, suggesting reduced starch retrogradation. Increased heat treatment increased degree of protein polymerization, observed in microstructures as increased gluten strand thickness and network density. Firmness and extensibility increased with increased parboil time; however, extension data indicated an overall weakening of microwave-treated pasta regardless of total cooking time. Overall, microwave pasteurization was shown to be a viable cooking method for pasta.

Improving functional properties of pea protein isolate for microencapsulation of flaxseed oil

Abstract Unhydrolysed pea protein (UN) forms very viscous emulsions when used at higher concentrations. To overcome this, UN was hydrolysed using enzymes alcalase, flavourzyme, neutrase, alcalase–flavourzyme, and neutrase–flavourzyme at 50 °C for 0 min, 30 min, 60 min, and 120 min to form hydrolysed proteins A, F, N, AF, and NF, respectively. All hydrolysed proteins had lower apparent viscosity and higher solubility than UN. Foaming capacity of A was the highest, followed by NF, N, and AF. Hydrolysed proteins N60, A60, NF60, and AF60 were prepared by hydrolysing UN for 60 min and used further for microencapsulation. At 20% oil loading (on a total solid basis), the encapsulated powder N60 had the highest microencapsulation efficiency (ME = 56.2). A decrease in ME occurred as oil loading increased to 40%. To improve the ME of N60, >90%, UN and maltodextrin were added. Flowability and particle size distribution of microencapsulated powders with >90% microencapsulation efficiency and morphology of all powders were investigated. This study identified a new way to improve pea protein functionality in emulsions, as well as a new application of hydrolysed pea protein as wall material for microencapsulation.

Effect of fish gelatin-gum arabic interactions on structural and functional properties of concentrated emulsions

Concentrated emulsions containing both proteins and polysaccharides are the basis for many commercial products; however, the effects of protein-polysaccharide interactions on the functional properties of these complex systems are often poorly understood from a fundamental standpoint. Hence, the objective of this study was to determine the effects of fish gelatin (FG)-gum arabic (GA) complexation at different aqueous phase pH (3.6, 5.0, and 9.0) on concentrated emulsion structure-function relationships. Concentrated emulsions were prepared using FG-GA mixtures and characterized by rheometry and confocal scanning laser microscopy (CSLM). CSLM images showed that all samples were O/W emulsions; emulsions with lower pH showed smaller oil droplets, greater homogeneity in size distribution, and higher stability. This was attributed to an increased number of FG-GA complexes in the emulsification. Electrostatic attractive interactions and charge neutralization created biopolymer associations with increased emulsification capacity. Samples with FG-GA mixtures at lower pH showed higher elastic moduli under small deformation and exhibited greater deviation between apparent and complex viscosities under the Cox-Merz rule, indicating increased gel network extension and greater intermolecular connectivity between adsorbed layers of adjacent oil droplets. These results can be used to incorporate protein-polysaccharide complexes as a suitable emulsifier in materials comprising concentrated emulsions.

Using Delphi Surveying Techniques to Gather Input from Non-Academics for Development of a Modern Dairy Manufacturing Curriculum.

The current face of the dairy manufacturing industry has changed from its traditional conception. Industry emphasis is moving away from traditional dairy products, such as fluid milk, ice cream, and butter, and moving toward yogurts, dairy beverages, and value-added products incorporating ingredients derived from milk and whey. However, many undergraduate dairy curricula still focus on production of fluid milk and traditional dairy products. In addition, despite the significant production of dairy products in the northwestern United States, there are few universities in the Pacific Northwest that offer courses in dairy products or manufacturing. Washington State Univ. and the Univ. of Idaho have developed a dairy manufacturing option to address these issues. To ensure that the curriculum was in alignment with current industry needs, dairy experts in the Pacific Northwest were asked to provide feedback on the proposed curriculum using a modified Delphi survey. Top industry concerns and desired knowledge and skills in new hires were identified. Survey participants emphasized the importance of including new processing technologies, waste management concepts, sustainability principles, engineering skills, and novel dairy products/ingredients in curriculum coverage. The results of the survey were used to modify the proposed curriculum to more closely address dairy industry needs. Alignment between industry needs and university curricula is vital to promote continued growth, development, and innovation in any industry; universities must be aware of changing needs in industry and modify curricula when necessary to address industry challenges.

Taking an Attention-Grabbing "Headlines First!" Approach to Engage Students in a Lecture Setting.

Lets face it. Traditional lectures do not consistently capture our students’ attention, especially when they are PowerPoint-driven and lack student/instructor interaction. Most of us have had the unfortunate feeling that our students were not fully engaged in our lectures, despite hours of preparation on our part. This sense of “wasted” investment of time can be especially frustrating for pretenure faculty, who must balance teaching, research, extension and administrative (as well as personal) responsibilities in order to be successful. How can we engage students in our course content, given limited time and resources to prepare lecture material and demonstrations? Active learning strategies are a possibility, but shifting courses from a lecture format to problem-based learning or a flipped format requires a significant time and effort investment from the instructor. Why not start by making lecture more fun and engaging for our students? Storytelling is an effective and efficient means of getting and maintaining our students’ attention and interest during lecture to drive home key points. The BSCS (Biological Sciences Curriculum Study) 5E Instructional Model provides a conceptual framework that emphasizes the primacy of student engagement in science education (Bybee). Our goal here is to provide practical examples and external references to show how “Headlines First!” storytelling can be used effectively to engage students in the science classroom.

The effect of storage temperature on blue cheese mechanical properties

Blue cheese is commonly aged for 60 days at 10°C after curing. However, some manufacturers store blue cheese at 4°C and the effect of lower storage temperature on blue cheese final properties is unknown. Thus, the objective of this study was to determine the effect of storage temperature and time on blue cheese mechanical behaviors. Blue cheeses were stored at 4 or 10°C for 77 days after production. Composition and small- and large-strain rheological behaviors were evaluated every 2 weeks of storage. Storage time had significant impact on blue cheese rheological behaviors; storage temperature did not. Large-strain compressive force and viscoelastic moduli decreased with storage time, and the extent of nonlinear viscoelastic behavior increased. These results indicated that sample microstructure likely weakened and was more easily deformed as storage time increased. Overall, blue cheese can be stored at 4-10°C without significant changes to its composition or mechanical behavior. PRACTICAL APPLICATIONS The results of this work can be used by blue cheese manufacturers to better understand the impact of storage time and temperature on blue cheese end quality. Manufacturers can take advantage of the effects of storage time on blue cheese mechanical behaviors to determine how long to age blue cheese to achieve the desired texture.

Waxy flour degradation – Impact of screw geometry and specific mechanical energy in a co-rotating twin screw extruder

Dextrinization of starch using extrusion processing is crucial to the quality of direct expanded products. To determine the extent of dextrinization, flour samples were extracted from a twin-screw extruder that had been brought to a sudden stop and molecular weights were determined by intrinsic viscosity. The screw profile and moisture feed content had the most significant impact on molecular weight reduction, reducing intrinsic viscosity from 1.75 to 0.70dL/g at the most. The breakdown, as shown by a reduction in intrinsic viscosity, had a strong negative correlation (r=-0.96) with specific mechanical energy. However, the extruder die did not have a measurable impact on the molecular weight reduction of waxy flour. Size exclusion chromatography confirmed intrinsic viscosity measurements were associated with reduction of the size of amylopectin molecules to approximately 1/10 the original molecular weight while native gliadin was nearly eliminated from the waxy flour following the extrusion treatments.

If You Don't Know, Ask! Using Expert Knowledge to Determine What Content Is Needed in an Undergraduate Food Quality Management and Control Course

Quality management and quality control of food products are critical to producing food that is safe to consume and has consistent quality and sensory attributes. The extent to which undergraduate students are equipped with competencies in quality management/control, in theory, has a direct connection with their career potential to ensure food products and/or services meet the expectations of consumers and society. However, the most important quality management/control competencies for undergraduate food science students have yet to be identified. The objective of this study was to determine key knowledge and skills in quality management/control needed by food science graduates. A modified Delphi method was used to gather consensus on these knowledge and skills from experts in food quality management/control. Surveys were used to establish a framework of the most relevant quality management/control concepts for undergraduate food science students to learn and organize these concepts into core domains according to their relative importance. A course outline for teaching an undergraduate course on food quality management/control was developed that detailed relevant topics and depth of coverage for each of these topics. The needs assessment method used in this study to align course content with food industrys needs may be used for a wide variety of course topics.