Effect of chitosan essential oil films on the storage-keeping quality of pork meat products

Edible films based on chitosan were prepared, with and without basil or thyme essential oils, with the aim of assessing their protective ability against lipid oxidation and their antimicrobial activity. Chitosan films had good oxygenbarrier properties, which were worsened by essential oil addition, especially when the film equilibrium moisture content increased. Due to the oxygen-barrier effect, all the films effectively protected pork fat from oxidation, in comparison to unprotected samples. In spite of the worsening of the oxygen-barrier properties, the films with essential oils were more effective than those of pure chitosan, which points to the chemical action of specific antioxidant compounds of the oils. Films were effective to control microbial growth in minced pork meat, although the incorporation of essential oils did not improve their antimicrobial activity. Throughout the storage, the films led to colour changes in minced pork meat associated with the conversion of myoglobin into metmyoglobin due to the reduction of the oxygen availability.The authors acknowledge the financial support provided by the Universitat Politecnica de Valencia (PAID-06-09-2834), Generalitat Valenciana (GV/2010/082) and Ministerio de Educacion y Ciencia (AGL2010-20694). Author J. Bonilla is deeply grateful to Generalitat Valenciana for a Santiago Grisolia Grant.Bonilla Lagos, MJ.; Vargas, M.; Atarés Huerta, LM.; Chiralt Boix, MA. (2014). Effect of chitosan essential oil films on the storage-keeping quality of pork meat products. Food and Bioprocess Technology. 7(8):2443-2450. https://doi.org/10.1007/s11947-014-1329-3S2443245078ASTM D3985. (1995). Standard test method for oxygen gas transmission rate through plastic films and sheeting using a coulometric sensor. 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Parallel Prefetching and Caching Is Hard

In this paper we study integrated prefetching and caching in parallel disk systems. This topic has gained a lot of interest in the last years which manifests itself in numerous recent approximation algorithms. This paper provides the first negative result in this area by showing that optimizing the stall time is APX-hard. This also implies that computing the optimal processing time is NP-hard, which settles an open problem posed by Kimbrel and Karlin

Fabrication, Functionalization, and Application of Electrospun Biopolymer Nanofibers

The use of novel nanostructured materials has attracted considerable interest in the food industry for their utilization as highly functional ingredients, high-performance packaging materials, processing aids, and food quality and safety sensors. Most previous application interest has focused on the development of nanoparticles. However, more recently, the ability to produce non-woven mats composed of nanofibers that can be used in food applications is beginning to be investigated. Electrospinning is a novel fabrication technique that can be used to produce fibers with diameters below 100 nm from (bio-) polymer solutions. These nanofibers have been shown to possess unique properties that distinguish them from non-woven fibers produced by other methods, e.g., melt-blowing. This is because first the process involved results in a high orientation of polymers within the fibers that leads to mechanically superior properties, e.g., increased tensile strengths. Second, during the spinning of the fibers from polymer solutions, the solvent is rapidly evaporated allowing the production of fibers composed of polymer blends that would typically phase separate if spun with other processes. Third, the small dimensions of the fibers lead to very high specific surface areas. Because of this the fiber properties may be greatly influenced by surface properties giving rise to fiber functionalities not found in fibers of larger sizes. For food applications, the fibers may find uses as ingredients if they are composed solely of edible polymers and GRAS ingredients, (e.g., fibers could contain functional ingredients such as nutraceuticals, antioxidants, antimicrobials, and flavors), as active packaging materials or as processing aids (e.g., catalytic reactors, membranes, filters (Lala et al., 2007), and sensors (Manesh et al., 2007; Ren et al., 2006; Sawicka et al., 2005). This review is therefore intended to introduce interested food and agricultural scientists to the concept of nano-fiber manufacturing with a particular emphasis on the use of biopolymers. We will review typical fabrication set-ups, discuss the influence of process conditions on nanofiber properties, and then review previous studies that describe the production of biopolymer-based nanofibers. Finally we briefly discuss emerging methods to further functionalize fibers and discuss potential applications in the area of food science and technology

Determination of Benzalkonium Chloride Partition in Micelle Solutions Using Ultrafiltration Method

The objectives of this study were to determine the concentrations of free benzalkonium chloride (BAC) and apparent partitions coefficients (Km) in micelle solutions and to explore its application in formulation development. Ultrafiltration (UF) was carried out using 10K Nanosep® devices and centrifugation at 5,000 rpm for 5 min. The separation of free BAC from micellar solutions was also conducted using ultracentrifugation (UC) method for the comparison with UF method. Capillary electrophoresis method was used for the identification of micelles. Results showed that a UF method was applicable for quantitatively evaluating BAC–micelle interaction in micellar solutions. Unlike UF, UC could not completely separate free BAC from the micelles. The free BAC concentrations in the micelle solutions decreased with increasing surfactant concentrations. Among polysorbate 80, cremophor EL, and tyloxapol, BAC had the highest Km in polysorbate 80 solutions. The Km was significantly lower in non-buffered aqueous solutions than that in citric buffers. Moreover, increasing surfactant concentrations led to reducing antimicrobial activity. The UF is a rapid and accurate method that minimally alters the micellar equilibrium for the determination of free BAC and Km in micellar solutions. In conclusion, free BAC concentration, which is a function of surfactant type, surfactant concentration, and ion strength of solution, is likely associated with the antimicrobial activity