Optimization of Sensory Properties of Cold Brew Coffee Produced by Reduced Pressure Cycles and Its Physicochemical Characteristics

The use of vacuum cycles for the cold extraction of coffee is a new process that leads to a significant reduction in process time of Cold Brew compared to conventional methods. This research aimed at specifying the necessary parameters for producing a consumer-accepted cold brew coffee by applying vacuum cycles. This was achieved by investigating the effect of the number of cycles and of the applied pressure (vacuum) on the physicochemical characteristics of the cold brew coffee, i.e., total dissolved solids (TDS%), pH, acidity, phenol and caffeine content and color. Furthermore, sensory evaluation took place by members of the Specialty Coffee Association of America (SCAA) to specify parameters such as coffee blend, coffee/water ratio, total water hardness and grind size and secondly to determine the optimal pressure and number of cycles for a tasty final beverage. The sensory and physiochemical characteristics of cold extraction coffee were investigated by Principal Component Analysis (PCA). It became evident that coffee extraction by applying two vacuum cycles at 205 mbar pressure produced the lowest intensity of physiochemical properties (caffeine, phenols, acidity, TDS% and pH), and the highest score of sensory characteristics (fragrance, body, acidity, flavor, balance, and aftertaste). Caffeine and phenol concentration of the optimal beverage were 26.66 ± 1.56 mg/g coffee and 23.36 ± 0.79 mg gallic acid/g coffee respectively. The physiochemical characteristics were also compared to a beverage of hot extraction of the same blend and ratio of coffee to water.     

Evaluation of Helically Coiled and Knitted Open Tubular Reactors for the Efficient Post-Column Determination of Tetrodotoxin by High-Performance Liquid Chromatography

A postcolumn fluorescence reaction system for the high-performance liquid chromatographic (HPLC) determination of tetrodotoxin in the silver-cheeked toadfish Lagocephalus sceleratus is discussed theoretically and investigated experimentally. Ion-pair chromatography with volatile ammonium perfluoroheptanoate was used for the separation of tetrodotoxin and 4,9-anhydrotetrodotoxin. The postcolumn reaction was based on the tetrodotoxin conversion to a quinazoline fluorescent compound under strong alkaline conditions. All postcolumn parameters were optimized that affected the sensitivity, dispersion, and stability. Helically coiled and knitted open tubular reactors composed of polyetheretherketone were constructed and characterized in detail. The performance of these reactors was evaluated on the basis of sensitivity and dispersion. Their optimal design is reported. The knitted reactors were more efficient than the relevant helically coiled reactors when higher reaction times are required. A 1500-µL polyetheretherketone knitted coil with 0.010″ internal diameter was optimum exhibiting higher pressure tolerances than Teflon coils. The HPLC postcolumn reaction method was evaluated in terms of linearity, sensitivity, accuracy, precision, and ruggedness. The linear dynamic ranges for tetrodotoxin and 4,9-anhydrotetrodotoxin were 40–3000 and 80–3000 ppb, respectively. The limits of detection and quantification were 12 and 41 ppb, respectively, for tetrodotoxin and 26 and 85 ppb, respectively, for 4,9-anhydrotetrodotoxin. The accuracy was evaluated by recovery measurements and the values for tetrodotoxin were between 90.7 and 93.6%. The use of a volatile perfuorocarboxylic acid as an ion-pair reagent allows confirmation of analytes in sample matrix by liquid chromatography tandem mass spectrometry using identical mobile phase conditions.     

Flexible long-term capacity planning in closed-loop supply chains with remanufacturing

We deal with long-term demand-driven capacity planning policies in the reverse channel of closed-loop supply chains (CLSCs) with remanufacturing, under high capacity acquisition cost coupled with uncertainty in actual demand, sales patterns, quality and timing of end-of-use product returns. The objective is to facilitate the decision-making when the management faces the dilemma of implementing either a strategy of early large-scale investments to benefit from economies of scale and capacity readiness, or a flexible strategy of low volume but more frequent capacity expansions. We consider a CLSC with two sequential product-types. We study the system’s response in terms of transient flows, actual/desired capacity level, capacity expansions/contractions and total supply chain profit, employing a simulation-based system dynamics optimization approach. Extensive numerical investigation covers a broad range of real-world remanufacturable products under alternative scenarios in relation to the market preference over product-types. The key findings propose flexible policies as improved alternatives to large-scale capacity expansions/contractions in terms of adaptability to the actual pattern of end-of-use product returns and involved risk in the investments’ turnover. Flexible policies are also proposed as practices to avoid overcapacity phenomena in collection and remanufacturing capacity and as robust policies to product demand. Their implementation is revealed to be even more important for the case of remanufacturing, when a high capacity acquisition unit-cost ratio (remanufacturing/collection) is coupled with strong economies of scale. Finally, results under different information sharing structures show changes in remanufacturing policies, thus justifying the importance of coordination between the decision-maker and the distributor.     

Official recycling and scavengers: Symbiotic or conflicting?

Nowadays, especially in developed countries, the traditional collection of end-of-use products by scavengers has been displaced by formal waste recovery systems. However, scavenging still exists, especially in places with collection capacity shortages and/or low living standards. Besides its obvious social implications, the financial and environmental aspects of scavenging are certainly not trivial. Informal recycling of waste electrical and electronic equipment (WEEE) by scavengers not only constrains profits of the formal system. In their effort to recover the value of end-of-use products, scavengers also pollute the environment if toxic substances leak when WEEE is not properly disposed of. We investigate the impact of scavenging on the operations of the formal recovery system of WEEE, under three regulatory measures, using system dynamics methodology. By using data from a real world closed-loop supply chain that operates in Greece extended numerical experimentation revealed that a legislation incorporating scavengers into the formal waste recovery system (instead of either ignoring or prohibiting their participation) is beneficial for economical, environmental and social sustainability.     

The impact of two-product joint lifecycles on capacity planning of remanufacturing networks

Capacity planning in the reverse channel of closed-loop supply chains (CLSCs) involves complex issues due to the different lifecycles of product offerings in combination with the variability regarding product usage time, quality level of used products and return patterns. (Georgiadis, P., Vlachos, D., Tagaras, G., 2006. The impact of product lifecycle on capacity planning of closed-loop supply chains with remanufacturing. Production and Operations Management 15; 514–527) developed a system dynamics (SD) model to study a CLSC with remanufacturing for a single product which incorporates a dynamic capacity modeling approach. We extend this SD model for two sequential product-types under two alternative scenarios regarding the market preferences over the product-types; in the first scenario, the market is considered showing no preferences, while in the second scenario, the demand over a product-type can be satisfied only by providing units of the specific type. We study how the joint lifecycles of two product-types, entry time of the second product-type to the market and used product return patterns affect the optimal policies regarding expansion and contraction of collection and remanufacturing capacities. The results of extensive numerical investigation are tested for their statistical significance using analysis of variance (ANOVA). In the first scenario, the results show that the system performs best when the two lifecycles form a trapezoid pattern for total demand while in the second scenario, when the two lifecycles form a triangular pattern.     

Bioaccessibility and Oxidative Stability of Omega-3 Fatty Acids in Supplements,Sardines and Enriched Eggs Studied Using a Static In Vitro Gastrointestinal Model

Modern dietary habits have created the need for the design and production of functional foods enriched in bioactive compounds for a healthy lifestyle. However, the fate of many of these bioactive compounds in the human gastrointestinal (GI) tract has not been thoroughly investigated. Thus, in the present study, the bioaccessibility of omega-3 fatty acids was examined. To that end, different foods and supplements underwent simulated digestion following the INFOGEST protocol. The selected samples were foods rich in omega-3 fatty acids both in free and bound form—i.e., dietary fish oil supplements, heat-treated fish, and eggs enriched with omega-3 fatty acids. The oxidation of polyunsaturated fatty acids (PUFAs) was measured at each stage of the digestion process using peroxide value (PV) and TBARS and by quantifying individual omega-3 fatty acids using a gas chromatograph with flame ionization detector (GC-FID). The final bioaccessibility values of omega-3 fatty acids were determined. Changes in the quantity of mono-saturated fatty acids (MUFAs) and saturated fatty acids (SFAs) were recorded as well. The results indicated a profound oxidation of omega-3 fatty acids, giving rise to both primary and secondary oxidation products. Additionally, stomach conditions seemed to exert the most significant effect on the oxidation of PUFAs during digestion, significantly decreasing their bioaccessibility. The oxidation rate of each fatty acid was found to be strongly correlated with its initial concentration. Finally, the oxidation pattern was found to be different for each matrix and emulsified lipids seemed to be better protected than non-emulsified lipids. It is concluded that digestion has a profound negative effect on omega-3 bioaccessibility and therefore there is a need for improved protective mechanisms.     

Real-time production planning and control system for job-shop manufacturing: A system dynamics analysis

Much attention has been paid to production planning and control (PPC) in job-shop manufacturing systems. However, there is a remaining gap between theory and practice, in the ability of PPC systems to capture the dynamic disturbances in manufacturing process. Since most job-shop manufacturing systems operate in a stochastic environment, the need for sound PPC systems has emerged, to identify the discrepancy between planned and actual activities in real-time and also to provide corrective measures. By integrating production ordering and batch sizing control mechanisms into a dynamic model, we propose a comprehensive real-time PPC system for arbitrary capacitated job-shop manufacturing. We adopt a system dynamics (SD) approach which is proved to be appropriate for studying the dynamic behavior of complex manufacturing systems. We study the system’s response, under different arrival patterns for customer orders and the existence of various types real-time events related to customer orders and machine failures. We determine the near-optimal values of control variables, which improve the shop performance in terms of average backlogged orders, work in process inventories and tardy jobs. The results of extensive numerical investigation are statistically examined by using analysis of variance (ANOVA). The examination reveals an insensitivity of near-optimal values to real-time events and to arrival pattern and variability of customer orders. In addition, it reveals a positive impact of the proposed real-time PPC system on the shop performance. The efficiency of PPC system is further examined by implementing data from a real-world manufacturer.