Browsing by Subject "Storage"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    Characterization and Pathway Investigation of Off-Flavor Formation in Stored Commercial Apple and Orange Juice Products
    (2016-02) Amann, Alexander
    Both apple and orange juice were investigated for off-flavor formation after 8 weeks of storage at 35°C. Furfural, p-vinylguaiacol, Furaneol (DMHF), β-fenchyl alcohol, α-terpinolene, α-terpineol, terpinen-4-ol, and methional were selected in orange juice while furfural, 5-methylfurfural, furfuryl alcohol, and β-damascenone were selected as off-flavor markers in apple juice. In orange juice, furfural was shown to be formed predominately from ascorbic acid degradation, and DMHF was formed from the degradation of reducing sugars. In apple juice, 5-MF, furfural, and furfuryl alcohol exhibited carbon labeling from reducing sugars. In orange juice, both GLN and TRP accelerated the formation of furfural, p-vinylguaiacol, Furaneol, α-terpineol, and terpinen-4-ol. In apple juice, both GLN and GABA promoted 5-methylfurfural, furfuryl alcohol, and β-damascenone formation over 8 weeks storage. Understanding the influence of fruit composition on the generation of off-flavors can aid in the development of approaches that yield juice with an improved flavor quality throughout shelf life.
  • Thumbnail Image
    Item
    Effect Of Steam Treatment On Chemical Changes Over Storage Of Intermediate Wheatgrass (Thinopyrum Intermedium) Refined, Partially Refined, And Whole Flour
    (2020-03) Hayek, Jenny
    Intermediate wheatgrass (IWG, Thinopyrum intermedium) is a perennial grain that has great environmental benefits such as reduced soil and water erosion due to its extensive root system. IWG has shown promise in its development as a food ingredient with high nutritional value. An understanding of its grain storage stability is essential to its commercial viability and success in food use. Grains are typically processed into flour and stored until use. While whole grains can be stored for eight to twelve years, flour has a significantly shorter shelf life. The storage stability of IWG flour has not yet been addressed. IWG has a relatively high fat content compared to wheat, which poses a potential issue regarding shelf life, as over time rancidity and decreases in antioxidant activity may occur. Thermal treatment, such as steaming, may be beneficial to increase grain shelf life by inactivating enzymes that are involved in lipid rancidity, namely lipase and lipoxygenase. Additionally, reducing the bran content via refinement may also prolong shelf life by decreasing fat content, but this would also reduce dietary fiber and antioxidant content, negatively affecting the praised nutritional value of IWG. An understanding of IWG flour storage stability and ascertaining methods to improve its stability is necessary for IWG’s commercialization and success. The objective of this work was to determine the effect of steam treatment, bran content, prior grain storage, and relative humidity on enzymatic activity, antioxidant content, antioxidant activity, and measures of hydrolytic and oxidative rancidity over IWG flour storage. Compositional analysis of IWG and hard red winter wheat (HRW) samples, harvested in 2016 and 2017, was conducted prior to storage using standard AOAC and AACCI methods. IWG grains were subjected to steam treatment in a sieve over a boiling water bath (100°C for 120 seconds), and then were left to equilibrate at room temperature for 24 hours. IWG grains (those that were steamed and those left as-is) were milled into whole, partially refined (75% bran), and refined flour. HRW grains were milled into whole and refined flour. Flour samples were stored at ambient temperature at 43% and 65% relative humidity (RH) for up to nine months. Samples were analyzed periodically for changes in enzymatic activity, antioxidant content and activity, and measures of hydrolytic and oxidative rancidity. Over storage, lipase (determined spectrophotometrically), and lipoxygenase (ferrous oxidation-xylenol orange assay) activities were evaluated. Carotenoid and hydroxycinnamic acid contents were determined by high performance liquid chromatography (HPLC). Antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and leucomethylene blue (LMB) assays. Hydrolytic rancidity was evaluated by measuring free fatty acids (FFA, titration), meanwhile oxidative rancidity was evaluated by measuring peroxide value (acetic acid-chloroform method), and hexanal content (static headspace gas chromatography). Compared to HRW, IWG had significantly higher protein, insoluble fiber, total dietary fiber, antioxidant content, and fat content. IWG had higher lipase yet lower lipoxygenase activity compared to HRW. The direct steam treatment utilized resulted in a significant reduction in lipase and lipoxygenase activity, without a significant reduction in antioxidant content. Overall, direct steam treatment and partial refinement had a positive effect on storage stability of flours from freshly harvested grains. Positive effects included reduced enzymatic activities and lower contents of rancidity products over storage, as well as preserved antioxidant content and activity over storage. The free fatty acid content increased over storage, but to a lesser extent in flour from steamed grains, confirming that steam treatment was effective in partial inactivation of lipase. Similarly, hydroperoxides increased over storage, but flour from steamed grains had lower hydroperoxide contents over time compared to flour from not steamed grains, confirming that steam treatment was effective in delaying oxidation product formation due to partial lipoxygenase inactivation and reduced level of free fatty acids. Partial refinement resulted in significantly lower measures of rancidity over storage, with lower enzymatic activities, compared to whole flours. Antioxidant content and activity were not greatly impacted by steaming or partial refinement, and were mostly preserved during storage. Results demonstrated that in comparison to HRW, IWG’s superior antioxidant content and activity contributed to the delayed appearance of oxidative rancidity measures. Results also demonstrated that flours stored at 43% RH had a slower progression of rancidity compared to samples stored at 65% RH. In IWG flours from one-year-old grains, steam treatment had a positive impact with regard to storage stability, preserving antioxidant contents and delaying the development of rancidity. However, with regard to lipase and lipoxygenase activity and antioxidant activity as measured by DPPH and LMB, steam treatment and refinement did not have a consistent, significant impact. The impact of grain storage prior to milling was positive in general, with lower enzymatic activities and similar antioxidant contents at the beginning and end of storage, and overall lower contents of free fatty acids, hydroperoxides, and hexanal at the end of storage in the resultant flour compared to flour from freshly harvested grains. Overall, the reduction of enzymatic activity by steam treatment resulted in lower contents of hydrolytic and oxidative rancidity products over storage. Partial refinement also resulted in lower contents of rancidity products and enzymatic activities over storage, while also retaining benefits linked with bran including dietary fiber and antioxidant content. Additionally, flours stored at 43% RH had a slower progression of rancidity compared to those stored at 65% RH. Thus, both steam treatment and partial refinement, combined with low RH storage conditions, may be useful to prolong the shelf life of IWG flour.
  • Thumbnail Image
    Item
    Hot and cold data identification: applications to storage devices and systems.
    (2012-08) Park, Dongchul
    Hot data identification is an issue of paramount importance in storage systems since it has a great impact on their overall performance as well as retains a big potential to be applicable to many other fields. However, it has been least investigated. In this dissertation, I propose two novel hot data identification schemes: (1) multiple bloom filter-based scheme and (2) sampling-based scheme. Then I apply them to the storage device and system such as Solid State Drives (SSD) and data deduplication system. In the multiple bloom filter-based hot data identification scheme, I adopt multiple bloom filters and hash functions to efficiently capture finer-grained recency as well as frequency information by assigning a different recency coverage to each bloom filter. The sampling-based scheme employs a sampling mechanism so that it early discards some of the cold items to reduce runtime overheads and a waste of memory spaces. Both hot data identification schemes empower each scheme to precisely and efficiently identify hot data in storage with less system resources. Based on these approaches, I choose two storage fields as their applications: NAND flash-based SSD design and data deduplication system. Particularly in SSD design, hot data identification has a critical impact on its performance (due to a garbage collection) as well as its life span (due to a wear leveling). To address these issues in SSD design, I propose a new hybrid Flash Translation Layer (FTL) design that is a core part of the SSD design. The proposed FTL (named CFTL) is adaptive to data access patterns with the help of the multiple bloom filter-based hot data identification algorithm. As the other application, I explore a data deduplication storage system. Data dedu- plication (for short, dedupe) is a special data compression technique that has been widely adopted especially in backup storage systems for backup time saving as well as storage saving. Unlike the traditional dedupe research that has focused more on the write performance improvement, I address its read performance aspect. In this section, I newly design a read cache in dedupe storage for a backup application to improve read performance by looking ahead their future references in a moving window with the combination of a hot data identification algorithm. This dissertation addresses the importance of hot data identification in storage areas and shows how it can be effectively applied to them in order to overcome the existing limitations in each storage venue.
  • Thumbnail Image
    Item
    Improving Application Performance in the Emerging Hyper-converged Infrastructure
    (2019-04) Wen, Hao
    In today's world, the hyper-converged infrastructure is emerging as a new type of infrastructure. In the hyper-converged infrastructure, service providers deploy compute, network and storage services on inexpensive hardware rather than expensive proprietary hardware. It allows the service providers to customize the services they can provide by deploying applications in Virtual Machines (VMs) or containers. They can have controls on all resources including compute, network and storage. In this hyper-converged infrastructure, improving the application performance is an important issue. Throughout my Ph.D. research, I have been studying how to improve the performance of applications in the emerging hyper-converged infrastructure. I have been focusing on improving the performance of applications in VMs and in containers when accessing data, and how to improve the performance of applications in the networked storage environment. In the hyper-converged infrastructure, administrators can provide desktop services by deploying Virtual Desktop Infrastructure application (VDI) based on VMs. We first investigate how to identify storage requirements and determine how to meet such requirements with minimal storage resources for VDI application. We create a model to describe the behavior of VDI, and collect real VDI traces to populate this model. The model allows us to identify the storage requirements of VDI and determine the potential bottlenecks in storage. Based on this information, we can tell what capacity and minimum capability a storage system needs in order to support and satisfy a given VDI configuration. We show that our model can describe more fine-grained storage requirements of VDI compared with the rules of thumb which are currently used in industry. In the hyper-converged infrastructure, more and more applications are running in containers. We design and implement a system, called k8sES (k8s Enhanced Storage), that efficiently supports applications with various storage SLOs (Service Level Objectives) along with all other requirements deployed in the Kubernetes environment which is based on containers. Kubernetes (k8s) is a system for managing containerized applications across multiple hosts. The current storage support for containerized applications in k8s is limited. To satisfy users' SLOs, k8s administrators must manually configure storage in advance, and users must know the configurations and capabilities of different types of the provided storage. In k8sES, storage resources are dynamically allocated based on users' requirements. Given users' SLOs, k8sES will select the correct node and storage that can meet their requirements when scheduling applications. The storage allocation mechanism in k8sES also improves the storage utilization efficiency. In addition, we provide a tool to monitor the I/O activities of both applications and storage devices in Kubernetes. With the capabilities of controlling client, network and storage with hyper-convergence, we study how to coordinate different components along the I/O path to ensure latency SLOs for applications in the networked storage environment. We propose and implement JoiNS, a system trying to ensure latency SLOs for applications that access data on remote networked storage. JoiNS carefully considers all the components along the I/O path and controls them in a coordinated fashion. JoiNS has both global network and storage visibility with a logically centralized controller which keeps monitoring the status of each involved component. JoiNS coordinates these components and adjusts the priority of I/Os in each component based on the latency SLO, network and storage status, time estimation, and characteristics of each I/O request.
  • Thumbnail Image
    Item
    Modeling, Optimization, and Detailed Design of a Hydraulic Flywheel-Accumulator
    (2014-07) Strohmaier, Kyle Glenn
    Improving mobile energy storage technology is an important means of addressing concerns over fossil fuel scarcity and energy independence. Traditional hydraulic accumulator energy storage, though favorable in power density, durability, cost, and environmental impact, suffers from relatively low energy density and a pressure-dependent state of charge. The hydraulic flywheel-accumulator concept utilizes both the hydro-pneumatic and rotating kinetic energy domains by employing a rotating pressure vessel. This thesis provides an in-depth analysis of the hydraulic flywheel-accumulator concept and an assessment of the advantages it offers over traditional static accumulator energy storage.After specifying a practical architecture for the hydraulic flywheel-accumulator, this thesis addresses the complex fluid phenomena and control implications associated with multi-domain energy storage. To facilitate rapid selection of the hydraulic flywheel-accumulator dimensions, computationally inexpensive material stress models are developed for each component. A drive cycle simulation strategy is also developed to assess the dynamic performance of the device. The stress models and performance simulation are combined to form a toolset that facilitates computationally-efficient model-based design.The aforementioned toolset has been embedded into a multi-objective optimization algorithm that aims to minimize the mass of the hydraulic flywheel-accumulator system and to minimize the losses it incurs over the course of a drive cycle. Two optimizations have been performed - one with constraints that reflect a vehicle-scale application, and one with constraints that reflect a laboratory application. At both scales, the optimization results suggest that the hydraulic flywheel-accumulator offers at least an order of magnitude improvement over traditional static accumulator energy storage, while operating at efficiencies between 75% and 93%. A particular hydraulic flywheel-accumulator design has been selected from the set of laboratory-scale optimization results and subjected to a detailed design process. It is recommended that this selection be constructed and tested as a laboratory prototype.