scholarly journals Assessment of Enzymatic Browning and Evaluation of Antibrowning Methods on Dates

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Mariam Al-Amrani ◽  
Ahmed Al-Alawi ◽  
Insaaf Al-Marhobi

Dates’ color is known to play a crucial role in determining the value and quality of the fruit. The color changes from the natural accepted golden color to unfavorable dark brown color during storage. In this study, the effect of different color preservation methods (modified atmosphere packaging, cold storage (4°C), sulfur dioxide gas (SO2), and blanching) and its relation to darkening due to action of the browning enzymes and melanin production were investigated. Polyphenol oxidase was shown to be active in all treatments except the samples treated with SO2 gas and steam blanching for ten minutes. Likewise, peroxidase activity showed a similar trend in all samples, but a decrease in activity was observed in sulfated samples and total inactivation in steam blanching for ten minutes. Moreover, sulfated samples have shown improvement in color compared to all other treatments, whereas the steamed samples showed the highest color deterioration. Concurrently, melanin content increased in all samples over the period of storage except in the sulfated samples. FTIR analyses of dates’ melanin have revealed similar structural feature to the reference melanin; however, some differences were noticed in the regions 2850–2950 cm-1 and 1690–1705 cm-1 which indicated major structural difference between the two melanin samples. More work is suggested to reveal structural and functional properties of dates’ melanin.

1990 ◽  
Vol 53 (3) ◽  
pp. 255-257 ◽  
Author(s):  
R. E. BRACKETT

Fresh bell peppers were individually shrink-wrapped in film (SW), sealed in gas-flushed (5% O2, 10% CO2, 85% N2) film (GP) pouches, or stored unpackaged in cardboard packing crates (CN). All samples were stored at 13°C and changes in populations of total aerobic microorganisms, yeasts and molds, members of Enterobacteriaceae, and lactic acid bacteria were determined. In addition, overall sensory quality, color changes, and surface pH were monitored. SW peppers developed higher populations of total aerobic microorganisms, yeasts and molds, and Enterobacteriaceae than did CN peppers, but populations of other groups of microorganisms were similar. Color and surface pH of peppers did not differ in any of the treatments. SW and GP peppers remained unspoiled at least 6 weeks, whereas CN peppers spoiled in 3 weeks.


2012 ◽  
Vol 21 (4) ◽  
pp. 421-429 ◽  
Author(s):  
Ferhan K. Sabir

Broccoli is rich in health-promoting compounds such as ascorbic acid and glucosinolates. However, amount of such compounds inevitably decrease along with the storage. This study was conducted to investigate the effects of 1-methylcyclopropene (1-MCP) and Modified Atmosphere Packaging (MAP) treatments alone or in combination on postharvest life and quality of broccoli heads during cold storage. MAP and 1-MCP+MAP significantly reduced weight loss, delayed surface color changes and chlorophyll breakdown, maintained visual quality, ascorbic acid, total phenol, soluble solid contents and titratable acidity compared with control as well as 1-MCP treatment. In 1-MCP plus MAP treated florets, approximate 47% and more chlorophyll and 24% more total phenol contents were found compared to control florets. 1-MCP plus MAP application better performed in maintaining the quality of broccoli florets during 28-day-storage. Overall results revealed that combined treatment can be recommended for commercial broccoli storage at 0 °C.


Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3445
Author(s):  
Olaf K. Horbańczuk ◽  
Artur Jóźwik ◽  
Jarosław Wyrwisz ◽  
Joanna Marchewka ◽  
Agnieszka Wierzbicka

The aim of this study was to evaluate the effect of the packaging system type on the physical characteristics and microbial changes in ostrich meat during refrigerated storage. The applied packaging systems were vacuum packaging (VP) and modified atmosphere packaging (MAP) using two combinations of gases: MAP1 (40% O2/40% CO2/20% N2) and MAP2 (60% O2/30% CO2/10% N2). Eight meat samples were obtained in three replicates for all parameters, except for pH, for which six replicates were obtained from the M. ilifibularis (IF) muscle, and were stored in a refrigerator at 2 °C and analyzed at 0, 4, 8, 12 and 16 days for the effect of packaging methods on physical meat quality. The initial pH (5.99) decreased at the end of the storage time for MAP1 to 5.81, whereas VP was stable from day 0 to 12 and increased up to 6.08 on day 16. Regarding meat color, the L* value increased during storage for MAP1 and MAP2 from 36.99 to 40.75 and 41.60, respectively, whereas it declined for VP to 34.22. The same tendencies were reported for redness (a*) and yellowness (b*). Drip loss was the lowest in MAP1 and highest in VP. The lowest total viable bacteria counts were identified in VP, as compared to MAP1 and MAP2.


Author(s):  
Md. Azizul Haque ◽  
Md. Asaduzzaman ◽  
Md. Sultan Mahomud ◽  
Md. Rizvi Alam ◽  
Alin Khaliduzzaman ◽  
...  

AbstractFresh-cut lettuce is a very well-known salad for today's routines because it obliges minimal preparation to minimize the loss of health beneficial vitamins, minerals, antioxidants and other phytochemicals. It is a prodigious challenge to serve its consumers fresh. Quality of freshly processed lettuce under high CO2 modified atmosphere packaging (MAP) has been investigated as a realistic alternative technique for its preservation. Storage under high CO2 atmospheric treatments exhibited a significant impact in microbial development, electrolyte leakage, volatile metabolites and sensory quality of fresh-cut iceberg lettuce. This storage condition (MAP 1: 5 kPa O2 and 20 kPa CO2 balanced by N2 at 7 °C for 6 days) inhibited the growth of mesophilic bacteria and yeasts; delayed the enzymatic browning (cut-edges and intact surface) of fresh-cut iceberg lettuce and overall visual quality was also in acceptance limit. The development of off-odors was perceived in high CO2 MAP as a consequence of volatiles (ethanol and acetaldehyde) accumulation which was persisted at an inexcusable level during 6 days of storage periods.


Sugar Tech ◽  
2012 ◽  
Vol 15 (2) ◽  
pp. 203-208 ◽  
Author(s):  
Dilip Kumar ◽  
Jarnail Singh ◽  
D. R. Rai ◽  
Mahesh Kumar ◽  
S. Bhatia

LWT ◽  
2007 ◽  
Vol 40 (3) ◽  
pp. 397-403 ◽  
Author(s):  
Víctor H. Escalona ◽  
Encarna Aguayo ◽  
Francisco Artés

2019 ◽  
Vol 5 (2) ◽  
pp. 132
Author(s):  
Nurlela Nurlela ◽  
Risnawati Risnawati

The Influence of Resin against the Change of Color on the Wall PaintThe quality of the paint is determined by the resin used. Synthetic resins for polymer paints are made by combining several monomers to achieve various characteristics. The incorporation of some monomers such as polyvinyl acetate resin, acrylic vinyl resin and acrylic styrene resin which act as a binder can affect the quality of the paint especially the color change. The purpose of this study is to find the color changes that occur on the wall paint by using Poly Styrene Acrylic , Poly Vinyl Acetate and Poly Vinyl Acrylic. From the results of the measurement of color difference, significant color change occurs in the Poly Vinyl Acetate (PVAc) + Poly Vinyl Acrylic (PVA) and Poly Styrene Acrylic (PSA). The results of the quality test of the three resins based on pH test, scrub test and viscosity test, PSA has better quality compared to PVA + PVAc and PVA resin. From the color difference measurement test, some things need to be considered, are temperature, film thickness, substrate color/background color and measurement conditions (measured in wet sample/in plate/dry surface) and test on resin added additive according to the type of each resin.Keywords: Paint, Resin, Color Changes, Poly Vinyl Acetate, Poly Styrene.ABSTRAK Kualitas dari cat sangat ditentukan oleh resin yang digunakan. Resin sintetis untuk cat berupa polimer yang dibuat dengan menggabung beberapa monomer untuk mencapai berbagai karakteristik. Penggabungan dari beberapa monomer seperti resin poli vinil asetat, resin vinil akrilik dan resin stirena akrilik yang berfungsi sebagai pengikat mampu mempengaruhi kualitas cat terutama dari perubahan warna. Tujuan dari penelitian ini adalah untuk mengetahui perubahan warna yang terjadi pada cat tembok dengan menggunakan Poli Stirena Akrilik, Poli Vinil asetat dan Poli Vinil Akrilik. Dari hasil pengukuran perbedaan warna, perubahan warna cukup signifikan terjadi pada resin Poli vinil Asetat (PVAc) + Poli Vinil Akrilik (PVA) dan resin  Poli Stirena Akrilik (PSA). Hasil uji Kualitas cat dari ketiga resin berdasarkan uji pH, uji scrub dan uji viscositas, PSA memiliki kualitas yang lebih baik dibandingkan dengan resin PVA+PVAc dan PVA. Dari pengujian pengukuran perbedaan warna, beberapa hal yang perlu di perhatikan, yaitu suhu, film thickness, warna substrat/background color dan kondisi pengukuran (diukur dalam keadaan wet sample/dalam bentuk plate/dry surface) dan pengujian terhadap resin yang ditambahkan zat aditif yang sesuai dengan tipe masing-masing resin tersebut.Kata Kunci: Cat, Resin, Perubahan Warna, Poli Vinil, Poli Stirena.


2014 ◽  
Vol 32 (5) ◽  
pp. 655-665 ◽  
Author(s):  
Me-Hea Park ◽  
Ji-Weon Choi ◽  
Yong-Bum Kim ◽  
Myeong-Hae Kim ◽  
Hee-Yeon Won ◽  
...  

2011 ◽  
Vol 17 (5) ◽  
pp. 702-709 ◽  
Author(s):  
S. Valadas ◽  
A. Candeias ◽  
J. Mirão ◽  
D. Tavares ◽  
J. Coroado ◽  
...  

AbstractIn this work, we present the results of an analytical method developed for detailed pigment identification, stratigraphy, and degradation of the paint layers of mural paintings applied in the study of the 17th century frescoes from the Misericordia Church of Odemira (Southwest Portugal). In situ X-ray fluorescence spectrometry analyses were performed on three panels of the mural paintings and complemented by colorimetric measurements. The different color areas were also sampled as microfragments (approx. 1 mm2) that were studied as taken or mounted in epoxy resin to expose the different paint layers. The microfragments of paint layers and their cross sections were characterized by optical microscopy and scanning electron microscopy coupled with energy dispersive X-ray spectrometry. Furthermore, elemental analysis was obtained with spatially resolved confocal synchrotron radiation μ-X-ray fluorescence spectrometry performed at ANKA synchrotron FLUO beamline. Occasionally, phase analysis by μ-X-ray diffraction was also performed. Results from the different techniques allowed pigment identification and, in some cases, the evaluation of color changes due to degradation processes and, considering the Southern Portugal geology, the identification of their possible provenance. The pigments used were essentially yellow, brown and red ochres, smalt blue, copper green, and black earths, probably from local sources.


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