H.E. Huff

Biomechanical comparison of median sternotomy closures.

BACKGROUND Poor healing of median sternotomy can significantly increase morbidity, mortality, and hospital costs. Effective union requires reliable sternal fixation. Although wire has proven the most reliable and widely used sternotomy closure material, no experimental studies have compared a large variety of wiring techniques in a human model. We developed an easily reproducible experimental model using cadaveric human sterna and compared several wiring methods to assess closure strength and stability. METHODS Fifty-three fresh adult human cadaveric sternal plates with adjacent ribs were fixed with specially designed spiked stainless steel clamps and attached to a texture analyzer. Single peristernal and transsternal, alternating single peristernal and transsternal, figure-eight peristernal, figure-eight pericostal, and Robicsek closures using no. 5 stainless steel wires were tested. We evaluated bone density, stiffness, and displacement using perpendicular, repetitive variable force loads of 800 Newtons cycling at a rate of 0.5 mm/s. RESULTS There were no significant differences in age, sex, or bone density in outcome measures of the sternal groups. No clamp failures or clamp damage to the specimens occurred. The single peristernal and alternating peristernal and transsternal closures proved superior in strength and stability (p < 0.001). The figure-eight peristernal, then the single transsternal, then the Robicsek were next stablest groups in decreasing order. The figure-eight pericostal closure had the highest failure rate (p < 0.001). CONCLUSIONS This novel model of sternotomy closure testing was reliable, inexpensive, and easily reproducible. The mechanical stability of peristernal and alternating peristernal and transsternal wires was significantly greater than that of the other tested methods. Pericostal figure-eight closures were not sufficiently stable to be considered a reliable method of primary sternotomy repair.

Textural characteristics of lowfat, fullfat and smoked cheeses: sensory and instrumental approaches

Abstract Research on the comparison of textural properties of lowfat, fullfat and smoked cheeses is yet to be reported. The objective of this study was to find textural differences in these cheeses by sensory and instrumental methods and to try to correlate the sensory and the instrumental data. Nine commercial cheeses were evaluated for aroma, flavor, and texture by descriptive analysis and were also subjected to instrumental texture profile analysis. The sensory evaluation by a panel of nine judges separated the cheeses into ‘smoked’ and ‘non-smoked’ based on aroma and flavor. On the basis of texture the judges categorized the cheeses into either ‘dry and crumbly’ or ‘sticky and creamy’. The texture profile analysis segregated the cheeses into ‘smoked’ and ‘non-smoked’. ‘Hardness’ (instrumental) was positively correlated to sensory texture attributes such as ‘dry’, ‘hardness’ and ‘crumbly’, which might indicate hardness of cheeses during mastication. The judges that participated in the panel were found to be very consistent as a group in their evaluation.

Effects of lipids and processing conditions on lipid oxidation of extruded dry pet food during storage

Abstract Effects of fat type (beef tallow and poultry fat), fat content (0–0.75 g kg −1 ) and processing conditions (initial moisture: 1.6–2 g kg −1 ; screw speed: 200–400 rpm) on lipid oxidation of extruded dry pet food were studied. The results showed that the lipid oxidation rate constant of the extruded dry pet food was a function of fat types, added fat content and feed moisture content. Control (no fat) samples had the highest lipid oxidation rate, as compared to the samples with fat addition. Samples with poultry fat had a higher lipid oxidation rate than those with beef tallow addition. Samples containing a higher fat content resulted in a lower rate of lipid oxidation during storage. Feed moisture content had the same effect as the fat content; the extrudates with a higher moisture content resulted in a lower lipid oxidative rate. Pet foods extruded at 300 rpm had a significantly higher lipid oxidation rate than the ones produced at 200 and 400 rpm. Lipid oxidation of the extrudates appeared to be affected mainly by the degree of extrudate expansion. Products with a higher degree of expansion, which had larger cells and thinner cell walls, were more susceptible to oxidation.

Mechanical properties of extruded high amylose starch for loose-fill packaging material

Extrudates of corn starch containing 700g/kg amylose, which may have potential as a loose-fill packaging material, were prepared using an APV Baker MPF50/25 twin-screw extruder. Their moisture sorption isotherm was established by equilibrating them over saturated salt solutions at 25°C. The salts used and their water activities (in parentheses) were: LiCl (0.11), CH 3 COOK (0.23), MgCl 2 (0.33), K 2 CO 3 (0.42), Mg(NO 3 ) staggered2 (0.53), NaNO 2 (0.63), and NaCl (0.75). Energy index (3–19.3 N·m/m 3 ), compressive strength (34–162 kPa), and spring index (58–79%) of the packaging materials were determined from their stress-strain curve using the Instron Universal Testing Machine with a data acquisition system. Both energy index and compressive strength increased with increasing water activity levels up to 0.53 and then decreased. The spring indices were not present at water activities 0.11 and 0.23, and behaved in a similar manner to compressive strength at higher water activities.

Puffing of okara/rice blends using a rice cake machine.

Okara is the insoluble byproduct of soymilk and tofu manufactures. It is cheap, high in nutrients, and possesses great potential to be applied to functional human foods. In this study, a puffed okara/rice cake product was developed with blends of okara pellets and parboiled rice. Consumer preference and acceptance tests were conducted for the product. Okara pellets were prepared by grinding the strands obtained from extruding a mixture of dried okara and rice flour (3:2, w/w) with a twin-screw extruder. Okara pellets and parboiled rice were blended in 4 ratios, 90:10, 70:30, 40:60, and 0:100 (w/w), and tempered to 14% and 17% moisture. The blends were puffed at 221, 232, and 243 degrees C for 4, 5, or 6 s. The okara/rice cakes were evaluated for specific volume (SPV), texture, color, and percent weight loss after tumbling. Overall, the decrease in okara content and increase in moisture, heating temperature and time led to greater specific volume (SPV) and hardness, lighter color, and lower percent weight loss after tumbling. The consumer tests indicated that the okara/rice cake containing 70% okara pellets was preferred and the 90% one was liked the least. The possible drivers of liking for the puffed okara/rice cakes could be the okara content, hardness, SPV, bright color, and percent weight loss after tumbling.

Laser Scanning System for Real-Time Mapping of Fiber Formations in Meat Analogues

High moisture extrusion has been used to produce vegetable meat analogues that resemble real animal meat and can provide significant health benefits. Since visual and textural properties are key factors for consumer acceptance, assessing fiber formation in the extruded products is important for quality control purpose. Recently, we developed a nondestructive photon migration method to quantify fiber formation in meat analogues. In this study, we implemented this technique in a real-time optical scanning system. This system can scan the entire sample area in real-time and provide 2-dimensional maps to visualize the degree of fiber formation and fiber orientation in the sample. The new system has a potential to provide a fast, nondestructive means for online monitoring of the fiber formation in meat analogues.

Nondestructive real-time monitoring of fiber formation in meat analogs

High moisture extrusion technology is capable of producing meat analogs which assemble real meat. Since visual and textural properties are the key factor for consumer acceptance, assessing fiber formation in extruded products is important for producing quality meat analogs with a great texture. Recently, we developed a photon migration method to assess fiber formation in meat analogs. In this paper, we present an implementation of this method in a real time scanning system. Acquired images were processed to characterize the fiber formation. This system provides a fast, non destructive means to determine the fiber formation in meat analogs.

Flexible Polyurethane Foam Extended with Corn Starch

The use of polyurethane foam is continuing to grow at a rapid pace throughout the world. This growth can be attributed to their light weight, excellent strength/weight ratio, energy absorbing performance (including shock, vibration, and sound), and comfort features of the polyurethane foams (Klempner and Frisch, 1991). Recently, there has been an increased interest in the use of renewable resources in the plastics industry (Bhatnagar et al, 1993; Carraher and Sperling, 1981; Cunningham and Carr, 1990; Cunningham et al, 1991, 1992a, and 1992b; Donnelly et al, 1991; Yoshida et al, 1987 and 1990). In addition, many patents covering processes for utilizing the plant components in the preparation of polyurethane foam have been issued in recent years (Dosmann and Steel, 1961; Hostettler, 1979; Kennedy, 1985; Otey et al, 1968). However, most of these studies focused on rigid polyurethane foam. Less attention has been paid to the flexible polyurethane foam system. Corn starch is a renewable raw material. As a carbohydrate, it contains many active hydrogens and hydroxyl groups. Thus, a great opportunity exists for using corn starch to modify or improve the physical and chemical properties of flexible polyurethane foams.