Heart valve diseases are among the leading causes of cardiac failure around the globe. Nearly 90,000 heart valve replacements occur in the USA annually. Currently, available options for heart valve replacement include bioprosthetic and mechanical valves, both of which have severe limitations. Bioprosthetic valves can last for only 10–20 years while patients with mechanical valves always require blood-thinning medications throughout the remainder of the patient’s life. Tissue engineering has emerged as a promising solution for the development of a viable, biocompatible and durable heart valve; however, a human implantable tissue engineered heart valve is yet to be achieved. In this study, a tri-leaflet heart valve structure is developed using electrospun polycaprolactone (PCL) and poly L-lactic acid (PLLA) scaffolds, and a set of in vitro testing protocol has been developed for routine manufacturing of tissue engineered heart valves. Stress-strain curves were obtained for mechanical characterization of different valves. The performances of the developed valves were hemodynamically tested using a pulse duplicator, and an echocardiography machine. Results confirmed the superiority of the PCL-PLLA heart valve compared to pure PCL or pure PLLA. The developed in vitro test protocol involving pulse duplicator and echocardiography tests have enormous potential for routine application in tissue engineering of heart valves.
The aim of this study is to assess the juice production potential of a highly perishable fruit, namely loquat and the effect of basic thermal and chemical treatment on the sensory attributes and phenolic content. The scarcity of loquat-based products on the market limits its consumption to raw loquat fruit. It is highly perishable and thus quickly loses its postharvest commercial quality. Loquat transformation into juice would increase the pellet of loquat-based products. Loquat fruit to loquat juice conversion value ranged between 1.79, 1.78, 2.41 and 2.39Kg of loquat fruit to produce 1kg of diluted fresh loquat juice, diluted fresh loquat juice with citric acid, pasteurized diluted loquat juice and pasteurized diluted loquat juice with citric acid respectively. The dilution factor was 0.2. All the Sensory attributes; taste, texture, appearance, aroma and overall-acceptance were significantly higher for both unpasteurized loquat juices when compared with the pasteurized ones. Total Soluble Solids (TSS) values and TSS/Titratable-Acidity of the two pasteurized loquat juices were significantly higher than those which were not, given that water-activity and pH did not differ. TSS was significantly and negatively correlated with all the sensory attributes. Finally yet importantly, the phenolic content of the untreated fresh loquat juice scored significantly the lowest while the phenolic effect of the other juices did not differ significantly from each other. When the phenolic content per100gr TSS where the loquat juice with 1% citric acid scored significantly the highest than all of the other juices which did not differ significantly from each other.
The aim of this study is to observe and assess the performance of Psychrotrophic Gram-negative bacteria, namely Pseudomonas fluorescens, which pose a significant spoilage problem in food, under different temperature, water activity (aw) and pH conditions. Noting that at aw 0.6 and 0.75 irrespective of temperature or pH and at temperatures 60 0 and 100 0 C irrespective of water activity or pH no survival was recorded. The Dvalue (Decimal reduction time) at 4 0 , 25 0 , 37 0 and 42 0 C differ significantly, with the one at 37 0 C was significantly the highest and that at 42 0 C was significantly the lowest. The optimum conditions were found to be at pH=6, aw=0.97 and temperature=37 0 C showing the significantly lowest generation time (7.69 min). At pH=6, aw=0.97 and temperatures of 4 0 and 25 0 C we have significantly different generation times of 46.75 and 10.9 min respectively. Concerning the z-value it was calculated at pH=4 (high acid food), pH=6 (low acid food) and pH=8 (alkaline food), at aw 0.82, 0.93 and 0.97 and from consequent D-values at temperatures 4 0 , 25 0 , 37 0 and 42 0 C and was shown to be 25.31±3.68. Outside of the optimum conditions, Pseudomonas fluorescens died at different rates. Within all pH-values, D-values at 42 0 C were significantly the lowest when compared to those at 4 0 , 25 0 and 37 0 C among the different aw-values. Thus changing only one factor, either storage temperature, pH or aw out of the optimum neighborhood will lead to the reduction of this bacteria, although at different rates.
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