A RESEARCH NOTE: EFFECT OF CITRIC ACID AND/OR ROSEMARY EXTRACT ON COLOR OF AN IRRADIATED BEEF MYOGLOBIN MODEL SYSTEM

To determine the effect of antioxidants and irradiation on meat color, myoglobin (Mb) was extracted from beef hearts. Mb was treated with one of four antioxidants (control, citric acid [CA], rosemary extract [RE] or combination of citric acid and rosemary extract [CA/RE]) and irradiated at 0.00 (Control), 0.50, 0.75, 1.00, 1.25, 1.50, 1.75 and 2.00 kGy. Samples were then evaluated for thiobarbituric reactive substances, pH, L*, a* and b* values, hue angles, and Chroma. RE- and CA-containing samples had the highest postirradiation L*, a* and b* values, indicating they were lighter, redder and more yellow than controls. In terms of hue angles, all samples treated with antioxidants were much closer to the true red axis ( a* =  0) of the CIE color space, both before and after irradiation, than was the control . The only color attribute affected by irradiation dose was L* value. Samples irradiated at 2.0 kGy were significantly lighter ( L* =  5.27) than samples that had not been irradiated ( L* =  1.28).

PRACTICAL APPLICATIONS

Irradiation is an effect method for extending the shelf life and improving the safety of fresh meat products; however, it can cause undesirable color changes at the surface of the meat, which appear to be the result of oxidative processes – therefore, reducing oxidation could effectively reduce color change. Studying pigment preservation is difficult in intact muscle tissue, so a myoglobin model system was developed for this purpose. Natural antioxidants were evaluated in this system. Rosemary extract and citric acid maintained color lightness and redness. Surface application of these antioxidants has the potential to preserve red meat color during irradiation.     

Imagination and situated cognition

Abstract

We describe a novel agent architecture based on the idea that cognition is imagined interaction, i.e. that cognitive tasks are performed by interacting with an imaginary world. We demonstrate the architecture by its application to a subsumption-based mobile robot. The robot's interactive abilities include exploration of an environment and goal-directed navigation within a previously explored environment. Imagination enables the robot to read and make use of maps, allowing it to reason about unfamiliar environments as well.     

A comparison between ceramic and polymeric membrane systems for casein concentrate manufacture

Skim milk microfiltration (MF) is a well established dairy processing operation to remove whey proteins. This is classically completed using ceramic membranes under the uniform transmembrane pressure (UTMP) concept. However, there is a growing interest in the use of spiral wound polymeric membranes for this purpose due to their lower capital cost. In this work we show that polymeric and ceramic membranes provide comparable performance during skim milk MF when operated at comparable levels of transmembrane pressure (TMP), shear stress and temperature. Operation is strongly affected by both TMP and temperature but is less affected by crossflow velocity under the conditions utilised here. However, while polymeric membranes offer similar performance, it will be operationally difficult to retain the necessarily low TMP at the industrial scale, due to the lack of a comparable UTMP configuration.     

POSTMODULAR SYSTEMS: ARCHITECTURAL PRINCIPLES FOR COGNITIVE ROBOTICS

Modular-functional decomposition is a fundamental tenet of computer science. Cognitive robotics, with strong roots in cognitive science and biology,replaces modular-functional decomposition with a more opportunistic approach. Nonetheless, we can extract heuristics with both analytic and synthetic power: architectural principles for postmodular systems. This paper describes three postmodular principles: imagination, shared grounding, and incremental adaptation. It briefly discusses examples of each drawn from existing systems. The paper concludes with an illustration of these three principles used in concert to build a system that progresses first to hand-eye coordination, then to planned complex reaching, and finally to shared attention.     

CONSUMER EVALUATION OF THE PALATABILITY OF USDA SELECT,USDA CHOICE AND CERTIFIED ANGUS BEEF STRIP LOIN STEAKS FROM RETAIL MARKETS IN LUBBOCK,TEXAS, U.S.A.

ABSTRACT

Select, Choice and Certified Angus Beef (CAB) strip loin steaks were sold in Lubbock, TX to determine consumer acceptability. A home survey was attached to each package of steaks (return = 191 steak evaluations). Consumers did not detect differences in tenderness or flavor, but rated CAB steaks juicier (P < 0.05) than Select or Choice. However, 68% of CAB consumers rated steaks as extremely or very tender, but less than half rated Choice and Select steaks the same way. Consumer tenderness and flavor scores for Select steaks were more variable, but consumer satisfaction and tenderness acceptability did not differ (P > 0.05) between grades. Trained sensory panelists rated CAB steaks higher (P < 0.05) than Choice or Select for all palatability traits except flavor intensity. Shear force decreased (P < 0.05) by quality grade as CAB steaks sheared with the least resistance. These results showed marbling influenced objective palatability measures and decreased the variation in both objective and consumer measures of palatability.

PRACTICAL APPLICATIONS

Quality grades were established to predict beef palatability, but marbling can be an unreliable predictor of tenderness. Branded beef programs, such as Certified Angus Beef (CAB), have been developed to distinguish higher palatability products and provide more consistent products for consumers. Consumers can distinguish between levels beef tenderness and are willing to pay a premium for tender beef. Moreover, consumers find product consistency is moderately important when purchasing fresh beef. Therefore, the purpose of this study was to determine consumer acceptability based on in‐home evaluations of strip loin steaks from United States Department of Agriculture Select and Choice grades and CAB purchased from a retail supermarket environment.

     

ENZYMATIC DIGESTION OF MUSCLE FROM MENHADEN (BREVOORTIA SPP.) AT DIFFERENT pHs

Solubilization of muscle from South American menhaden, Brevoortia spp., was done with and without added proteolytic enzymes. Pepsin and trypsin were isolated from the stomach and the pyloric caeca of croaker (Micropogonias furnieri) respectively, and used for enzymatic solubilization. Digestion of muscle proteins was carried out at 8C for 20 h with the pH maintained at either 3, 4, 5, 6, 7, 8, 9 or 10. The hydrolytic action was evaluated by measuring the concentration of peptides and proteins solubilized from previously frozen muscle or from lyophilized muscle.
The protein solubility of menhaden muscle was optimum at basic pH; approximately 50–60% of the previously frozen or lyophilized muscle was soluble after incubation without added enzyme at pH 9.0. All of the protein was solubilized from lyophilized menhaden muscle with purified trypsin at pH 10.0. Addition of croaker pepsin to menhaden muscle increased protein solubility by only 10–15%. Digestion of menhaden muscle with both pepsin and trypsin from croaker resulted in a similar increase in protein solubility as obtained by addition of only trypsin.
Similar results were obtained with crude croaker stomach extracts and with purified pepsin, and also with crude pyloric caeca extract and with purified trypsin. Complete solubilization of menhaden muscle with croaker pyloric caeca extract may be an inexpensive way to separate the protein from lipids and prepare a protein isolate from this underutilized specie. Additional work is needed to characterize the functional properties of the menhaden protein extract obtained by digestion of the flesh at alkaline pH with croaker trypsin.     

A RESEARCH NOTE: ANTIOXIDANT EFFECTS ON COLOR OF AN IRRADIATED BOVINE MYOGLOBIN MODEL SYSTEM

To determine whether antioxidants could protect meat color during irradiation, we extracted myoglobin (Mb) from beef hearts, treated it with one of four antioxidants (control, citric acid [CA], ascorbic acid [AA], ethylenediamine tetraacetic acid [EDTA] or propyl gallate [PG]) and irradiated it at 0.00, 1.25, or 2.50 kGy. The myoglobin model system was then evaluated for pH; Commission Internationale de L'Eclairage (CIE) L *, a * and b * values; hue angle; chroma; and thiobarbituric acid reactive substances (TBARS). Adding CA and AA to the beef myoglobin model system resulted in higher L *, a * and b * values than did EDTA and PG, indicating that these samples were lighter, redder and more yellow. EDTA- and PG-containing samples were more similar to controls containing no antioxidants. Hue angle and chroma supported these findings. Irradiation had no effect on pH, color or TBARS. These results indicate that antioxidants have more influence on beef color than irradiation and that the acidic antioxidants have the potential for preserving color.

PRACTICAL APPLICATIONS

Irradiation has the potential to reduce the microbial load on meat products, producing safer foods for consumers. However, a number of reports have indicated that irradiation can compromise the bright, cherry red color of fresh meat. Off-color will result in consumer rejection of products that may be safe. Antioxidants have the potential to preserve meat color by affecting the state of myoglobin; however, studying these effects in vivo is challenging because of the complexity of the system. In this model system, which was devoid of enzymatic reducing systems and equivalents, the acidic antioxidants, ascorbic acid (AA) and citric acid (CA), were most effective in preserving the color of the pigment. These antioxidants appear to have the greatest potential for preserving fresh meat color during irradiation.     

Interleukin-1β regulates metalloproteinase activity and leptin secretion in a cytotrophoblast model

Implantation is one of the most regulated processes in human reproduction, by endocrine and immunological systems. Cytokines are involved in embryo-maternal communication and an impaired balance could result in pregnancy loss. Here we investigated the effect of interleukin 1-β on the activity of two important metalloproteinases (MMP-2 and MMP-9) that are involved in extracellular matrix remodeling as well as the secretion of leptin, one of the reproductive hormones actively regulating their activity and secretion. We found that IL-1β activates matrix metalloproteinase activity as well as increases leptin secretion. We propose that this interleukin, through the regulation of leptin, in turn activates matrix metalloproteinases which results in an increased cytotrophoblast invasion.