From protein to indicator. Towards temperature uniformity mapping in high pressure processing reactors

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Headspace fingerprint as a potential multivariate intrinsic indicator to monitor temperature variation of thermal in-pack processes: A case-study on broccoli puree

The aim of the presented study was to evaluate the potential of a headspace fingerprint as a multivariate intrinsic indicator for monitoring temperature history variation that can occur, for example, during in-pack food processing at the product level. Using solid-phase micro-extraction gas chromatography mass spectrometry (SPME-GC–MS), we monitored the extracted volatile fraction of a series of 8 well-defined thermally processed broccoli purees, differing only in the maximal process temperature reached. Our results showed that the relative composition of the extracted volatile fraction clearly depended on the processing intensity (as a measure for thermal variation) applied. In addition, this headspace fingerprinting approach, including multivariate data analytical approaches, allowed a swift selection of specific intrinsic fingerprint markers. The evaluation of the concentration of each of these markers allows to discriminate between the different processing intensities. However, we suggest to perform a linear combination of the information from relevant identified intrinsic fingerprint markers given the increased reliability of a multiple response indicator. The presented approaches are a promising proof-of-principle that has potential to be exploited for monitoring other processing non-uniformities as well.Thermal treatment is by far still the most commonly used preservation method for food with a high water content. In-pack retort treatment commonly results in some temperature non-uniformity occurring during the treatment at both the reactor and/or the product level. While the use of thermocouples for acquiring time-temperature history is often an excellent solution, the use of intrinsic food components as indicators can be of great advantage for process monitoring. So far usually pre-selected single component intrinsic indicators were suggested. In this work, we are presenting the utilization of the headspace fingerprint as a multivariate intrinsic indicator instead of using a single compound. From the industrial point of view, we present an innovative concept of monitoring product specific extracted volatile fraction, followed by selection of specific intrinsic fingerprint markers and linearly combining the information from those markers. While the advanced data analysis for selection of the fingerprint markers will have to be done per specific product, only the linear combination of the specific data from the markers can be used for routine analysis. Such concept can provide increased reliability due to the utilization of a non-pre-selected multiple response indicator with a relatively feasible monitoring of the markers using gas chromatography mass spectrometry (GC–MS).status: publishe

Influence of harvest maturity and logistics on pineapple (Ananas comosus [L.] Merr.) fruit volatiles assessed by headspace solid phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC/MS)

Profiling of volatiles from pineapple fruits was performed at four ripening stages using headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC/MS). In total, 142 volatiles were detected, of which 132 were identified. Multivariate data analysis was carried out to assess the effect of post-harvest storage on volatiles composition of green-ripe sea-freighted pineapple in comparison to air-freighted fruits harvested at full maturity. The latter fruits were characterised by volatiles described as potent odorants in pineapples, such as δ-octalactone, γ-lactones, 1-(E,Z)-3,5-undecatriene and 1,3,5,8-undecatetraene, as well as various methyl esters. In contrast, post-harvest storage of green-ripe sea-freighted fruits resulted in an increased formation of ethyl esters, acetates, acetoxy esters and alcohols, thus allowing the authentication of sea- and air-freighted pineapples, respectively. Particularly, compounds presumably derived from methyl-branched amino acid catabolism were identified in the fruits at later post-harvest stages. In addition, physicochemical traits were determined to characterise the fruit maturity stages.publisher: Elsevier articletitle: Influence of harvest maturity and fruit logistics on pineapple (Ananas comosus [L.] Merr.) volatiles assessed by headspace solid phase microextraction and gas chromatography–mass spectrometry (HS-SPME-GC/MS) journaltitle: Food Chemistry articlelink: http://dx.doi.org/10.1016/j.foodchem.2013.10.092 content_type: article copyright: Copyright © 2013 Elsevier Ltd. All rights reserved.status: publishe

Effect of different combined mechanical and thermal treatments on the volatile fingerprint of a mixed tomato–carrot system

The effect of volatile profiles of a mixed vegetable puree comprised of tomato and carrot due to different thermo-mechanical process conditions has been thoroughly investigated using an untargeted GC–MS chemical fingerprinting approach. This resulted in a selection of discriminative marker volatile compounds in mixed vegetable puree, which acting as the witness of the process footprint and can therefore be related to the quality changes like micro-structure, heat distribution, etc. Moreover, when individual component, in a mixed vegetable system, are processed together (‘all-in-one processed’) vis-a-vis processed separately and then mixed together (‘split-stream processed’) different extent of chemical and enzymatic reactions can potentially induce change in volatile profiles. This work showed the potential of different process types to generate distinct headspace profiles of a mixed tomato–carrot system. This consciousness can be a starting point for more targeted tailoring of the flavour of mixed tomato–carrot products

Establishing a multiresponse model of the in vitro lipid digestion process

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Understanding the effect of processed- and mastication-induced common bean characteristics to engineer its digestive starch functionality

Common beans are nutritious and sustainable commodities in which nutrients are bio-encapsulated in natural barriers. Processing is impeccable to increase their palatability, but also to increase embedded macronutrients digestibilities. In an ongoing PhD work, we investigated how different variables at the level of processing and digestion (e.g. in vivo mastication) affect structural and in vitro starch digestion kinetics of common beans. In a first part 1, we studied the effect of conventional cooking on macro- and microstructural characteristics. We observed that cooking time was an important factor to influence the hardness and microstructural composition of the beans. From short to long cooking times, microstructural properties shifted from free starch granules over cell clusters to free, closed cells. These structures were the result of processing and a simple mechanical desintegration with mortle and pestle. Secondly2, we investigated the effect of in vivo mastication on the tissue structural breakdown pattern. Within the mastication panel, different mastication characteristics were observed but free, closed cells were detected to be the characteristic microstructure of bean tissue when cooked within the palatable range. Finally3,4, we investigated the natural barrier role (e.g. cell wall, protein matrix) on in vitro starch digestion kinetics. We proved that starch digestion in bean cells is a multistep process, in which digestive enzymes need to cross the cell wall barrier, reach their substrate and metabolites produced need to leave the cell in order to be considered bio-accessible3. We also observed that by cooking beans at different intensities, different structural characteristics of proteins can be observed, which can be one of the reasons why beans being cooked with different processing intensities clearly show different digestibilities4. Pallares Pallares, A. (1) (2018). Food Res. Int. ; (2) (2019). Submitted to Br. J. Nut. ; (3) (2018). Food and Funct.; (4) (2019). Submitted to Food Funct.status: publishe

In vitro starch hydrolysis of common bean process-induced structures

Common beans have natural structural barriers playing a fundamental role in the fate of starch upon consumption. In this study, the influence of process-induced modifications of natural barriers on the in vitro starch hydrolysis of common bean cotyledons was investigated. Initially, water-soaked common beans were subjected to three different processes, each as a function of time: a thermal treatment (HT, 95⁰C, 0.1MPa), a high-pressure treatment (HP, 20⁰C, 600MPa), and a combined high-temperature high-pressure treatment (HTHP, 95⁰C, 600MPa). After processing, cotyledons were isolated and the time-dependent evolution of hardness (whole cotyledons) and microstructural properties (after mechanical degradation) was determined. Subsequently, for a number of mechanically disrupted samples with specific microstructural characteristics, the time-dependent evolution of in vitro small intestinal starch hydrolysis (expressed as percentage of digested starch) was determined. It was detected that HP samples were mostly characterized by free, non-swollen starch granules, whilst in samples obtained by HT and HTHP there was major presence of cell clusters at early processing times and free cells at longer times. However, HTHP samples had higher microstructural heterogeneity than HT samples. A fractional conversion model properly described the time-dependent evolution of in vitro starch hydrolysis. From the joint confidence regions of the estimated kinetic parameters, the presence of statistically significant differences among the samples became clear. In general, rate constants of all samples were similar, whilst the final values of digested starch exhibited major differences. The predicted final digested starch decreased with an increase in the level of starch bio-encapsulation (from free gelatinized starch to cell clusters) and a decrease in the degree of starch gelatinization. In samples with the same level of starch bio-encapsulation (free cells), the observed differences might be attributed either to a different degree of starch gelatinization or to a distinct cell wall porosity induced by a longer processing time.status: publishe

The potential of multiresponse modelling in the context of in vitro lipid digestion

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Processing as a tool to manage digestive barriers in plant-based foods: recent advances

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