43 research outputs found
Analysis of Thermoelectric Coolers as Energy Harvesters for Low Power Embedded Applications
The growing popularity of solid state thermoelectric
devices in cooling applications has sparked an increasing diversity of
thermoelectric coolers (TECs) on the market, commonly known as
âPeltier modulesâ. They can also be used as generators, converting
a temperature difference into electric power, and opportunities are
plentiful to make use of these devices as thermoelectric generators
(TEGs) to supply energy to low power, autonomous embedded
electronic applications. Their adoption as energy harvesters in this
new domain of usage is obstructed by the complex thermoelectric
models commonly associated with TEGs. Low cost TECs for the
consumer market lack the required parameters to use the models
because they are not intended for this mode of operation, thereby
urging an alternative method to obtain electric power estimations
in specific operating conditions. The design of the test setup
implemented in this paper is specifically targeted at benchmarking
commercial, off-the-shelf TECs for use as energy harvesters in
domestic environments: applications with limited temperature
differences and space available. The usefulness is demonstrated by
testing and comparing single and multi stage TECs with different
sizes. The effect of a boost converter stage on the thermoelectric
end-to-end efficiency is also discussed
Effect of Lactic Acid Fermentation on Volatile Compounds and Sensory Characteristics of Mango (Mangifera indica) Juices
This research article published by MDPI, 2022Fermentation is a sustainable bio-preservation technique that can improve the organoleptic
quality of fruit juices. Mango juices were fermented by monoculture strains of Lactiplantibacillus
plantarum subsp. plantarum (MLP), Lacticaseibacillus rhamnosus (MLR), Lacticaseibacillus casei (MLC),
Levilactobacillus brevis (MLB), and Pediococcus pentosaceus (MPP). Volatile compounds were sorbed
using headspace solid phase microextraction, separated, and identified with gas chromatography mass spectrometry. Forty-four (44) volatile compounds were identified. The control, MPP, and MLB
had higher amounts of ethyl acetate, ethyl butyrate, 2-hexenal, 2,6-nonadienal, 2,2-dimethylpropanal,
ÎČ-selinene, Îł-gurjunene, α-copaene, and ÎŽ-cadinene, while MLC, MLP, and MLR had higher amounts
of 2,3-butanedione and a cyclic hydrocarbon derivate. Consumers (n = 80) assessed their overall
liking and characterized sensory attributes (appearance, color, aroma, flavor, consistency, acidity, and
sweetness) using check-all-that-apply, and penalty analysis (just-about-right). Overall liking was
associated with âmango colorâ, âpulpâ, âmango aromaâ, âsweetâ, ânatural tasteâ, and âmango flavorâ that
described the control, MLB, MLC and MPP. Juices MLR and MLP were described as âbitterâ, âsourâ,
âaftertasteâ, and âoff-flavorâ. Multivariate analysis revealed relationships between the volatile com pounds, mango juices fermented by different lactic acid bacteria, and sensory characteristics. Thus,
the type of lactic acid bacteria strains determined the volatile and sensory profile of mango juices
Effect of lactic acid fermentation of watermelon juice on its sensory acceptability and volatile compounds
This research article published by Elsevier Ltd., 2021Fermentation increases food shelf-life but is characterized by changes that affect product's perception. Watermelon juice was fermented with Lactobacillus plantarum (WJ-LP), L. rhamnosus (WJ-LR), L. casei (WJ-LC), L. brevis (WJ-LB) and Pediococcus pentosaceus (WJ-PP). Their sensory characteristics and volatile compounds were investigated by consumers and Headspace Solid Phase Microextraction integrated with Gas Chromatography-Mass Spectrometry, respectively. WJ-PP and WJ-LB were most liked and perceived with âwatermelon-flavorâ, ânatural tasteâ, âsweetâ and âwatermelon-colorâ while WJ-LC, WJ-LP and WJ-LR were least liked and perceived as âsourâ, âbitterâ, âoff-flavorâ, âaftertasteâ and âintense-flavorâ. Fifty-four volatiles were identified. After fermentation, alcohols, ketones, monoterpenes, acids, and furans increased while aldehydes and alkanes decreased. Lactic acid fermentation introduced 4-decanone and 2,3-butanedione in WJ-LB, WJ-LC, WJ-LP and WJ-LR, however, heptanal, 2-heptenal, 2,6-nonadienal, 2-decenal, and 2,4-decadienal in WJ-LC, heptanal, 2-hexenal, 2-heptenal, 2,6-nonadienal, 2-decenal and octanal in WJ-LR and 2,6-dimethyl-2,6-octadiene in WJ-LP disappeared. Juice sensory profiles were associated with their volatile compounds
Hyphenated in-tube roasting with GC-MS method as new approach to evaluate the aroma potential of Tanzanian cocoa beans
status: publishe
Inline roasting hyphenated with GC-MS as an innovative approach for assessment of cocoa fermentation quality and aroma formation potential
Today, the cocoa industry is in great need of faster and robust analytical techniques to objectively assess incoming cocoa quality. In this work, inline roasting hyphenated with a cooled injection system coupled to a gas chromatograph-mass spectrometer (ILR-CIS-GC-MS) has been explored for the first time to assess fermentation quality and/or overall aroma formation potential of cocoa. This innovative approach resulted in the in-situ formation of relevant cocoa aroma compounds. After comparison with data obtained by headspace solid phase micro extraction (HS-SPME-GC-MS) on conventional roasted cocoa beans, ILR-CIS-GC-MS data on unroasted cocoa beans showed similar formation trends of important cocoa aroma markers as a function of fermentation quality. The latter approach only requires small aliquots of unroasted cocoa beans, can be automatated, requires no sample preparation, needs relatively short analytical times (<1h) and is highly reproducible.publisher: Elsevier
articletitle: Inline roasting hyphenated with gas chromatographyâmass spectrometry as an innovative approach for assessment of cocoa fermentation quality and aroma formation potential
journaltitle: Food Chemistry
articlelink: http://dx.doi.org/10.1016/j.foodchem.2016.03.004
content_type: article
copyright: Copyright © 2016 Elsevier Ltd. All rights reserved.status: publishe
HS-SPME COMPOSITION OF VIRGIN OLIVE OIL EVALUATED BY GC-MS ANALYSIS AND MS-BASED ELECTRONIC NOSE TECHNOLOGY
status: publishe