Influence of pectin properties and processing conditions on thermal pectin degradation

Texture degradation of fruits and vegetables during thermal processing is partly due to pectin depolymerization. In this contribution we investigate the influence of pectin properties (degree and pattern of methoxylation) and processing conditions (pH 2.0, 3.0, 5.0 and 7.0; temperatures of 80 up to 110 °C) on pectin degradation rate constants. Pectins with different degrees and patterns of methoxylation were prepared and heated, the extent of acid hydrolysis, β-elimination and demethoxylation was assayed as a function of treatment time. As the degree of methoxylation and pH decreased, β-elimination rate constants decreased while acid hydrolysis rate constants increased. Demethoxylation rate constants were minimal at pH 3.0 and increased both at lower and higher pH. Reaction rate constants were not considerably influenced by the pattern of methoxylation. All reaction rate constants increased with increasing temperature. As β-elimination rates are reduced by competing demethoxylation, both rate constants were compared. The ratio of these reaction rate constants showed no trend with pH. However, an increase in degree of methoxylation or temperature resulted in a more pronounced increase in β-elimination rate constants than in demethoxylation rate constants.     

Effect of Pectinmethylesterase Infusion Methods and Processing Techniques on Strawberry Firmness

Strawberry halves were pretreated with fungal pectinmethylesterase (PME) and calcium chloride using, respectively, passive osmotic infusion, vacuum‐assisted infusion, and pressure‐assisted infusion with the aim to improve the firmness. The vacuum‐assisted procedure was observed to be the only method able to accomplish an uptake of infusion solution and hence capable of improving the firmness of the strawberries. Significantly less firmness increase was realized when tomato PME was vacuum‐infused instead of fungal PME. Strawberry halves were pretreated by vacuum‐assisted infusion with fungal PME and calcium chloride and were subsequently subjected to thermal treatments at 60 °C and 80 °C and pressure treatments at about 400 MPa and 550 MPa. For all treatments studied, the pretreated sample was significantly firmer compared with the reference sample. For the thermal processes, the residual firmness relative to the initial value before treatment was depending on the temperature of the treatment and not on the pretreatment. However, vacuum‐assisted infusion of PME and calcium could limit the portion of firmness loss due to pressure treatment to 30% compared with 80% for non‐pretreated fruits.     

Occurrence,prevention and remediation of toxigenic fungi and mycotoxins in silage: a review

Ruminants are considered to be less sensitive towards mycotoxins than monogastric animals because rumen microbiota have mycotoxin‐detoxifying capacities. Therefore the effect of mycotoxins towards ruminants has been studied to a lesser extent compared with monogastric animals. Worldwide, a high proportion of the ruminant diet consists of silages made of forage crops (i.e. all parts of the crop above the stubble are harvested). In practice, silages are often contaminated with multiple mycotoxins. Exposure to a cocktail of mycotoxins can hamper animal production and have severe health consequences. In this article the different aspects associated with mycotoxin contamination of silage are reviewed ‘from seed to feed’. An overview is given on the occurrence of toxigenic fungal species and their concomitant mycotoxins in forage crops before and after ensiling. The mycotoxin load of visually non‐mouldy samples and mouldy hot spots within the same silo is also compared. Subsequently, this review delves into different problem‐solving strategies. A logical first step is prevention of mould growth and mycotoxin production in the field, during harvest and during ensiling. If prevention should fail, several remediation strategies are available. These are listed, mainly focusing on the possibilities of microbial degradation of mycotoxins in vivo in silage. © 2015 Society of Chemical Industry     

Towards a better understanding of the pectin structure-function relationship in broccoli during processing: Part I—macroscopic and molecular analyses

To investigate the structure-function relationship of pectin during (pre)processing, broccoli samples (Brassica oleracea L. cultivar italica) were subjected to one of the following pretreatments: (i) low-temperature blanching (LTB), (ii) LTB in combination with Ca²⁺ infusion, (iii) high-pressure pretreatment (HP), (iv) HP in combination with Ca²⁺ infusion, or (v) no pretreatment (control sample), whether or not in combination with a thermal treatment of 15 min at 90 °C. The macroscopic attributes of broccoli were linked to the chemical structure of broccoli pectin. By enhancing the cross-linking of pectic polymers, both LTB and HP reduced the texture loss that occurred during thermal processing of broccoli. During these pretreatments, homogalacturonan was de-esterified by pectin methylesterase, which led to changes in pectin solubility. When LTB or HP was combined with Ca²⁺ infusion, changes in the structure of pectin occurred, however not always reflected at the macroscopic level. The degree of esterification of pectin in Ca²⁺-soaked broccoli samples was lower compared to non-Ca²⁺-soaked samples and, in addition, a higher amount of ionically cross-linked pectin was retrieved.     

Energy saving in existing buildings by an intelligent use of interoperable ICTs

In this paper, we report a methodology, developed in the context of Smart Energy Efficient Middleware for Public Spaces European Project, aimed at exploiting ICT monitoring and control services to reduce energy usage and CO₂ footprint in existing buildings. The approach does not require significant construction work as it is based on commercial-off-the-shelf devices and, where present, it exploits and integrates existing building management systems with new sensors and actuator networks. To make this possible, the proposed approach leverages upon the following main contributions: (a) to develop an integrated building automation and control system, (b) to implement a middleware for the energy-efficient buildings domain, (c) to provide a multi-dimensional building information modelling-based visualisation, and (d) to raise people’s awareness about energy efficiency. The research approach adopted in the project started with the selection, as case studies, of representative test and reference rooms in modern and historical buildings chosen for having different requirements and constraints in term of sensing and control technologies. Then, according to the features of the selected rooms, the strategies to reduce the energy consumptions were defined, taking into account the potential savings related to lighting, heating, ventilation, and air conditioning (HVAC) systems and other device loads (PC, printers, etc.). The strategies include both the control of building services and devices and the monitoring of environmental conditions and energy consumption. In the paper, the energy savings estimated through simulation, for both HVAC and lighting, are presented to highlight the potential of the designed system. After the implementation of the system in the demonstrator, results will be compared with the monitored data.     

A SUITABILITY STUDY OF SATELLITE EMULATION BY AIRBORNE PLATFORMS

For the design of satellite links, detailed knowledge of the transmission characteristics is important. Development issues such as channel measurements, feasibility and performance studies, pre-operational demonstration and verification tests, etc., are necessary or desirable before launch. For this task, another satellite might and should eventually be used. However, if a suitable test satellite is not available and if a tower, mountain, or cliff is not feasible, a proper airborne platform is necessary to emulate the characteristics of the satellite under investigation as closely as possible. This situation is assumed in the following. In this paper, theoretical as well as practical arguments are derived and collected, respectively: (i) to guide the selection of a suitable platform; (ii) to predict its limitations; and (iii) to consider the time-variant behaviour of satellite orbiting. The capabilities of a helicopter platform and of an airplane platform are demonstrated, supported by data recently collected in several test campaigns. © 1997 by John Wiley & Sons, Ltd.