Superiority of microwaves over conventional heating to preserve shelf-life and quality of kiwifruit puree

[EN] The effect of both microwave (1000 W-340 s) and conventional heating (97 degrees C-30 s) on the quality and shelf-life of kiwifruit puree was investigated. The growth of microorganisms and the evolution of enzyme activity, colour, pH, bioactive compounds and antioxidant activity in the product during storage at 4, 10 and 22 degrees C were checked. The storage temperature had a significant (p < 0.05) impact on both the shelf-life and the nutritional and functional value of the samples: the higher the temperature, the significantly (p <0.05) faster the rate of both the sample spoilage and the loss of the bioactive compounds. On the other hand, thermal processing significantly (p < 0.05) reduced the growth of microorganisms and the degradation rate of some bioactive compounds in a 12-59%, as well as leading to enzyme and colour stabilization. A longer shelf-life (123 days at 4 degrees C) and a superior preservation of colour (Delta E-SE = 6.54) and bioactive compounds (57-67%) were obtained when microwave heating was the technology selected to process the kiwifruit puree. Microwave heating was considered a suitable means of preserving kiwifruit puree that might be successfully employed as an innovation tool with which to help safe, high-quality and minimally processed kiwifruit based-products reach the market.The authors thank the Ministerio de Educacion y Ciencia for the financial support given throughout the Projects AGL 2010-22176 and AGL 2010-22206-C02-01 and the Generalitat Valenciana for the Grant awarded to the author Maria Benlloch.Benlloch Tinoco, M.; Igual Ramo, M.; Rodrigo Aliaga, MD.; Martínez Navarrete, N. (2015). Superiority of microwaves over conventional heating to preserve shelf-life and quality of kiwifruit puree. Food Control. 50:620-629. https://doi.org/10.1016/j.foodcont.2014.10.006S6206295

Evaluation of alternative preservation treatments (water heat treatment, ultrasounds, thermosonication and UV-C radiation) to improve safety and quality of whole tomato

Previously optimised postharvest treatments were compared to conventional chlorinated water treatment in terms of their effects on the overall quality of tomato (‘Zinac’) during storage at 10 °C. The treatments in question were water heat treatment (WHT = 40 °C, 30 min), ultrasounds (US = 45 kHz, 80 %, 30 min), thermosonication (TS =40 °C, 30 min, 45 kHz, 80 %) and ultraviolet irradiation (UV-C: 0.97 kJ m−2). The quality factors evaluated were colour, texture, sensorial analysis, mass loss, antioxidant capacity, total phenolic content, peroxidase and pectin methylesterase enzymatic activities, and microbial load reduction. The results demonstrate that all treatments tested preserve tomato quality to some extent during storage at 10 °C. WHT, TS and UV-C proved to be more efficient on minimising colour and texture changes with the additional advantage of microbial load reduction, leading to a shelf life extension when compared to control trials. However, at the end of storage, with exception of WHT samples, the antioxidant activity and phenolic content of treated samples was lower than for control samples. Moreover, sensorial results were well correlated with instrumental colour experimental data. This study presents alternative postharvest technologies that improve tomato (Zinac) quality during shelf life period and minimise the negative impact of conventional chlorinated water on human safety, health and environment.info:eu-repo/semantics/publishedVersio

Grass track and its role as a green infrastructure strategy within Stockholm’s public transport sector : A qualitative study of the Spårväg Syd project as a future tram project with a social example from Hammarby Sjöstad

The implementation of grass tracks is uncommon in Stockholm compared to Central Europe where it is more popularized. As more tram projects are planned in the future such as the Spårväg Syd project, the aim of this study is to explore the role of grass tracks in the public transport sector by theoretically conceptualising grass tracks as a green infrastructure strategy. The research questions were to study how residents perceive the grass track between Sicka Udde and Sickla Station, and how the grass track could contribute to noise concerns, traffic safety, and financial resource in the Spårväg Syd project. Qualitative methods were used in which online surveys were sent out to residents in Hammarby Sjöstad and interviews with the municipality and county workers from Lund, Norrköping and Stockholm were conducted. The result showed that the resident was more positive about the grass track compared to the municipality and county workers which highlighted the additional cost and work effort to provide the public with a well-maintained and visually attractive grass track. The conclusion of this study has covered previous and new discoveries which open discussions for further reflection on what project planners shall consider before deciding to implement grass tracks in future tram projects.

Heat inactivation and reactivation of broccoli peroxidase. Jourrnal of agricultural and food chemistry

Heat inactivation characteristics differed for acidic (A), neutral (N), and basic (B) broccoli peroxidase. At 65°C, A was the most heat stable followed by N and B. The activation energies for denaturation were 388, 189, and 269 kJ/mol for A, N, and B, respectively. Reactivation of N occurred rapidly, within 10 min after the heated enzyme was cooled and incubated at room temperature. The extent of reactivation varied from 0 to 50% depending on the isoenzyme and heating conditions (temperature and time). The denaturation temperature allowing the maximum reactivation was 90°C for A and horseradish peroxidase (HRP) and 70 and 80°C for B and N, respectively. In all cases, heat treatment at low temperatures for long times prevented reactivation of the heated enzymes. Calcium (5 mM) increased the thermal stability of N and B but had no effect on reactivation. The presence of 0.05% bovine serum albumin decreased thermal stability but increased the extent of reactivation of A.

Subcritical liquified dimethyl ether and supercritical fluid carbon dioxide extraction of gamma oryzanol from rice bran acid oil

Gamma oryzanol (γ-oryzanol) is a bioactive compound in rice bran acid oil, a by-product of the rice bran oil refining process that possesses various pharmacological properties. This study investigated the effect of green technology supercritical fluid carbon dioxide extraction (SF–CO2) and subcritical liquified dimethyl ether extraction (SUBLDME) of γ-oryzanol from rice bran acid oil. Results showed that subcritical liquified dimethyl ether extracted oryzanol at 4865.25 mg/100 g from rice bran acid oil without pretreatment by hexane and ethyl acetate compared with supercritical fluid carbon dioxide extraction (2569.04 mg/100 g), with high extraction efficiency (62.73 vs 18.86%). Further extraction of the filter cake remaining from supercritical fluid carbon dioxide extraction from rice bran acid oil without pretreatment using subcritical liquified dimethyl ether extraction gave the highest percentage yield and γ-oryzanol contents (8128.51 mg/100 g). Supercritical fluid carbon dioxide extraction together with subcritical liquified dimethyl ether extraction showed promise as a green technology to extract γ-oryzanol from rice bran acid oil. Further studies are required to optimize both SF-CO2 and SUBLDME extraction methods to increase the γ-oryzanol content