Water-soluble biopolymers from heat-treated and high pressure homogenized vegetable purées: investigating their emulsion forming and stabilizing capacities.

The emulsion forming and stabilizing capacities of water-soluble biopolymers originating from the aqueous (serum) phase of heat-treated and high pressure homogenized purées were investigated. The serum biopolymers were characterized and then utilized as emulsifier/stabilizer in simple oil-in-water emulsions. The resulting emulsions were stored at 4 °C and monitored for 2 weeks. Results revealed that carrot and tomato sera contained higher amounts of pectin and lower protein compared to broccoli. The serum pectic biopolymers exhibited distinct molecular structures, depending on the vegetable origin. Given these natural biopolymer composition and characteristics, emulsions with small droplet sizes were observed at pH 3.5. However, emulsions at pH 6.0 showed large mean droplet sizes, except for the emulsion formulated with carrot serum. Regardless of the pH, emulsions containing carrot serum biopolymers exhibited high capacity to form fine emulsions that were stable during the 2-week storage period at low temperature. This study clearly shows the capacity of natural water-soluble biopolymers isolated from the serum phase of vegetable purées to form fine emulsion droplets and maintain its stability during storage, especially in the case of carrot serum biopolymers.

Pulse seeds as promising and sustainable source of ingredients with naturally bioencapsulated nutrients: Literature review and outlook.

Pulse seeds are nutritious and sustainable matrices with a high level of intrinsic microstructural complexity. They contain high-quality plant-based protein and substantial amounts of slowly digestible starch and dietary fiber. Starch and protein in pulses are located inside cotyledon cells that survive cooking and subsequent mechanical disintegration, hence preserving natural nutrient bioencapsulation. In this context, several authors have explored a number of techniques to isolate individual cotyledon cells from these seeds, aiming to unveil their digestive and physicochemical properties. In recent years, isolated pulse cotyledon cells are also being highlighted as promising novel ingredients that could improve the nutritional properties of traditionally consumed food products. Even more, they could enable to implement a strategy for increasing pulse intake in populations where these seeds have not been traditionally consumed. This review mainly focuses on the reported digestive, physicochemical, and technofunctional properties of pulse cotyledon cells isolated through different techniques, preceded by a descriptive summary of the nutritional properties, structural organization, and traditional process chain of pulse seeds. It also offers an outlook of research directions to take, based on the identified research gaps. All in all, it is clear that isolation of pulse cotyledon cells using diverse techniques constitutes a promising strategy for the development of pulse-based ingredients where natural bioencapsulation of macronutrients is preserved. However, much more research is needed at the level of ingredient characterization to better understand the effect of starting pulse seed material, isolation technique, and isolation conditions on the nutritional and functional properties of the finished product(s) where the isolated cells are (to be) used.

Reaction pathways and factors influencing nonenzymatic browning in shelf-stable fruit juices during storage.

The occurrence of nonenzymaticbrowning in fruit juices during storage is a major quality defect. It negatively affects consumer acceptance and consumption behavior and determines the shelf-life of these products. Although nonenzymatic browning of fruit juices has been the subject of research for a long time, the exact mechanism of the nonenzymatic browning reactions is not yet completely understood. This review paper aims to give an overview of the compounds and reactions playing a key role in nonenzymatic browning during the storage of fruit juices. The chemistry of the plausible reactions and their relative importance will be discussed. To better understand nonenzymatic browning, factors affecting these reactions will be reviewed and several strategies and methods to evaluate color changes and browning will be discussed. Nonenzymatic browning involves three main reactions: ascorbic acid degradation, acid-catalyzed sugar degradation, and Maillard-associated reactions. The most important NEB pathway depends on the matrix. Nonenzymatic browning is affected by many factors, such as the juice composition, the pH, the oxygen availability (packaging material), and the storage conditions. Nonenzymatic browning can thus be considered as a complex problem. To characterize color changes and browning and obtain insight into the browning mechanism of fruit juices, food scientists applied several approaches and strategies. These included the use of model systems with/without the addition of labeled compound and real systems as well as advanced analytical methods.

Thermal treatment of common beans (Phaseolus vulgaris L.): Factors determining cooking time and its consequences for sensory and nutritional quality.

Over the past years, the shift toward plant-based foods has largely increased the global awareness of the nutritional importance of legumes (common beans (Phaseolus vulgaris L.) in particular) and their potential role in sustainable food systems. Nevertheless, the many benefits of bean consumption may not be realized in large parts of the world, since long cooking time (lack of convenience) limits their utilization. This review focuses on the current insights in the cooking behavior (cookability) of common beans and the variables that have a direct and/or indirect impact on cooking time. The review includes the various methods to evaluate textural changes and the effect of cooking on sensory attributes and nutritional quality of beans. In this review, it is revealed that the factors involved in cooking time of beans are diverse and complex and thus necessitate a careful consideration of the choice of (pre)processing conditions to conveniently achieve palatability while ensuring maximum nutrient retention in beans. In order to harness the full potential of beans, there is a need for a multisectoral collaboration between breeders, processors, and nutritionists.

How postharvest variables in the pulse value chain affect nutrient digestibility and bioaccessibility.

Pulses are increasingly being put forward as part of healthy diets because they are rich in protein, (slowly digestible) starch, dietary fiber, minerals, and vitamins. In pulses, nutrients are bioencapsulated by a cell wall, which mostly survives cooking followed by mechanical disintegration (e.g., mastication). In this review, we describe how different steps in the postharvest pulse value chain affect starch and protein digestion and the mineral bioaccessibility of pulses by influencing both their nutritional composition and structural integrity. Processing conditions that influence structural characteristics, and thus potentially the starch and protein digestive properties of (fresh and hard-to-cook [HTC]) pulses, have been reported in literature and are summarized in this review. The effect of thermal treatment on the pulse microstructure seems highly dependent on pulse type-specific cell wall properties and postharvest storage, which requires further investigation. In contrast to starch and protein digestion, the bioaccessibility of minerals is not dependent on the integrity of the pulse (cellular) tissue, but is affected by the presence of mineral antinutrients (chelators). Although pulses have a high overall mineral content, the presence of mineral antinutrients makes them rather poorly accessible for absorption. The negative effect of HTC on mineral bioaccessibility cannot be counteracted by thermal processing. This review also summarizes lessons learned on the use of pulses for the preparation of foods, from the traditional use of raw-milled pulse flours, to purified pulse ingredients (e.g., protein), to more innovative pulse ingredients in which cellular arrangement and bioencapsulation of macronutrients are (partially) preserved.

Barriers impairing mineral bioaccessibility and bioavailability in plant-based foods and the perspectives for food processing.

Plant-based foods gain more importance since they play a key role in sustainable, low-meat and healthy diets. In developing countries, these food products, especially legumes and cereals, are important staple foods. Nevertheless, the question arises on how efficient they are to deliver minerals and if it is useful to encourage their consumption to reduce the prevalence of mineral deficiencies? This review paper focuses on the discrepancy between the mineral content and the amount of minerals that can be released and absorbed from plant-based foods during human digestion which can be attributed to several inherent factors such as the presence of mineral antinutrients (phytic acid, polyphenols and dietary fiber) and physical barriers (surrounding macronutrients and cell wall). Further, this review paper summarizes the effects of different processing techniques (milling, soaking, dehulling, fermentation, germination and thermal processing) on mineral bioaccessibility and bioavailability of plant-based foods. The positive impact of these techniques mostly relies on the fact that antinutrients levels are reduced due to removal of fractions rich in antinutrients and/or due to their leaching into the processing liquid. Although processing can have a positive effect, it also can induce leaching out of minerals and a reduced mineral bioaccessibility and bioavailability.

Insight into non-enzymatic browning of shelf-stable orange juice during storage: A fractionation and kinetic approach.

BACKGROUND: Non-enzymatic browning (NEB) is the main quality defect in shelf-stable orange juice and other fruit juices during storage. Previous studies on NEB focused solely on the soluble fraction of orange juice, regardless of the fact that both soluble and insoluble fractions turn brown during extended storage. Clear evidence of the relative contribution of both fractions to NEB is currently lacking in the literature. This study investigated the contribution of the soluble and insoluble fractions of orange juice, which were obtained by centrifugation and ethanol precipitation, to NEB during storage. Changes in different NEB-related attributes, such as ascorbic acid (AA) degradation, and the browning index (BI), were quantified and kinetically modeled. RESULTS: Evaluation of color during storage showed that the orange juice and the soluble compound-containing fractions turned brown whereas the insoluble fractions did not. The soluble compound-containing fractions showed exactly the same browning behavior with storage as the plain orange juice. Based on the kinetic parameters obtained, the degradation of AA, the hydrolysis of sucrose, the increase in the glucose and fructose content, and the formation of furfural and 5-hydroxymethylfurfural during storage were similar for the plain orange juice and the soluble compound-containing fractions. CONCLUSION: This work provided evidence that the soluble fraction of orange juice plays the major role in NEB, unlike the insoluble fraction, which seems to make no contribution. Results from this work also demonstrate the potential use of the soluble fraction as an orange-juice-based model system of reduced complexity that can be used for the further investigation of NEB processes. © 2020 Society of Chemical Industry.

Effect of process-induced common bean hardness on structural properties of in vivo generated boluses and consequences for in vitro starch digestion kinetics.

In the present study, we evaluated the effect of process-induced common bean hardness on structural properties of in vivo generated boluses and the consequences for in vitro starch digestion. Initially, the impact of human mastication on the particle size distribution (PSD) of oral boluses from common beans with different process-induced hardness levels was investigated through a mastication study. Then the effect of structural properties of selected boluses on in vitro starch digestion kinetics was assessed. For a particular process-induced hardness level, oral boluses had similar PSD despite differences in masticatory parameters between participants of the mastication study. At different hardness levels, a clear effect of processing (P<0·0001) was observed. However, the effect of mastication behaviour (P=0·1141) was not significant. Two distinctive fractions were present in all boluses. The first one was a cotyledon-rich fraction consisting of majorly small particles (40-125 µm), which could be described as individual cells based on microscopic observations. This fraction increased with a decrease in process-induced hardness. The second fraction (>2000 µm) mostly contained seed coat material and did not change based on hardness levels. The in vitro starch digestion kinetics of common bean boluses was only affected by process-induced hardness. After kinetic modelling, significant differences were observed between the reaction rate constant of boluses generated from the hardest beans and those obtained from softer ones. Overall this work demonstrated that the in vitro nutritional functionality of common beans is affected to a greater extent by structural properties induced by processing than by mechanical degradation in the mouth.

Ground and Low-Lying Excited States of NbC3-/0 Clusters: Assignment of the Anion Photoelectron Spectra from Multiconfigurational Calculations.

The BP86 DFT, CCSD(T), and CASPT2 methods were employed to study the low-lying states of NbC3-/0 clusters. The anionic and neutral ground states were determined to be the 1A1 and 12A1 of the cyclic-NbC3-/0 isomers. All bands in the photoelectron spectra of the NbC3- cluster were interpreted based on electron detachment processes from the 1A1 of the cyclic-NbC3- isomer. The X, A, B, and C bands in the spectra are, respectively, ascribed to the transitions from 1A1 to the 12A1, 2B1, 22A1, and 2B2 states. The wave function of the initial 1A1 anionic state exhibits a pronounced multireference character that plays to some extent a role in the 1A1 → 12A1 and the 1A1 → 22A1 ionizations. Only the 1A1 → 2B2 transition appears as a clear one-electron detachment process. The Franck-Condon factor simulations for the 1A1 → 12A1 and 1A1 → 2B1 transitions are consistent with the observed vibrational progressions of the X and A bands in the spectra.

Understanding the Relations Among the Storage, Soaking, and Cooking Behavior of Pulses: A Scientific Basis for Innovations in Sustainable Foods for the Future.

The world faces challenges that require sustainable solutions: food and nutrition insecurity; replacement of animal-based protein sources; and increasing demand for convenient, nutritious, and health-beneficial foods; as well as functional ingredients. The irrefutable potential of pulses as future sustainable food systems is undermined by the hardening phenomenon that develops upon their storage under adverse conditions of temperature and relative humidity. Occurrence of this phenomenon indicates storage instability. In this review, the application of a material science approach, in particular the glass transition temperature concept, is presented to explain phenomena of storage instability such as the occurrence of hardening and loss of viability under adverse storage conditions. In addition to storage (in)stability, application of this concept during processing of pulses is discussed. The state-of-the-art on how hardening occurs, that is, mechanistic insights, is provided, including a critical evaluation of some of the existing postulations using recent research findings. Moreover, the influence of hardening on the properties and processing of pulses is included. Prevention of hardening and curative actions for pulses affected by the hardening phenomenon are described in addition to the current trends on uses of pulses and pulse-derived products. Based on the knowledge progress presented in this review, suggestions for the future include: first, the need for innovation toward implementation of recommended solutions for the prevention of hardening; second, the optimization of the identified most effective and efficient curative action against hardening; and third, areas to focus on for elucidation of mechanisms of hardening, although existing analytical methods require advancement.

Shelf-life dating of shelf-stable strawberry juice based on survival analysis of consumer acceptance information.

BACKGROUND: Accurate shelf-life dating of food products is crucial for consumers and industries. Therefore, in this study we applied a science-based approach for shelf-life assessment, including accelerated shelf-life testing (ASLT), acceptability testing and the screening of analytical attributes for fast shelf-life predictions. Shelf-stable strawberry juice was selected as a case study. RESULTS: Ambient storage (20 °C) had no effect on the aroma-based acceptance of strawberry juice. The colour-based acceptability decreased during storage under ambient and accelerated (28-42 °C) conditions. The application of survival analysis showed that the colour-based shelf-life was reached in the early stages of storage (≤11 weeks) and that the shelf-life was shortened at higher temperatures. None of the selected attributes (a* and ΔE* value, anthocyanin and ascorbic acid content) is an ideal analytical marker for shelf-life predictions in the investigated temperature range (20-42 °C). Nevertheless, an overall analytical cut-off value over the whole temperature range can be selected. CONCLUSIONS: Colour changes of strawberry juice during storage are shelf-life limiting. Combining ASLT with acceptability testing allowed to gain faster insight into the change in colour-based acceptability and to perform shelf-life predictions relying on scientific data. An analytical marker is a convenient tool for shelf-life predictions in the context of ASLT. © 2017 Society of Chemical Industry.

Influence of Pectin Structural Properties on Interactions with Divalent Cations and Its Associated Functionalities.

Pectin is an anionic cell wall polysaccharide which is known to interact with divalent cations via its nonmethylesterified galacturonic acid units. Due to its cation-binding capacity, extracted pectin is frequently used for several purposes, such as a gelling agent in food products or as a biosorbent to remove toxic metals from waste water. Pectin can, however, possess a large variability in molecular structure, which influences its cation-binding capacity. Besides the pectin structure, several extrinsic factors, such as cation type or pH, have been shown to define the cation binding of pectin. This review paper focuses on the research progress in the field of pectin-divalent cation interactions and associated functional properties. In addition, it addresses the main research gaps and challenges in order to clearly understand the influence of pectin structural properties on its divalent cation-binding capacity and associated functionalities. This review reveals that many factors, including pectin molecular structure and extrinsic factors, influence pectin-cation interactions and its associated functionalities, which makes it difficult to predict the pectin-cation-binding capacity. Despite the limited information available, determination of the cation-binding capacity of pectins with distinct structural properties using equilibrium adsorption experiments or isothermal titration calorimetry is a promising tool to gain fundamental insights into pectin-cation interactions. These insights can then be used in targeted pectin structural modification, in order to optimize the cation-binding capacity and to promote pectin-cation interactions, for instance for a structure build-up in food products without compromising the mineral nutrition value.

Antioxidant Capacity of Beetroot: Traditional vs Novel Approaches.

Red beetroot has been ranked among the 10 most potent antioxidant vegetables, although only extraction-based methods have been used to evaluate its total antioxidant capacity. Therefore, the present study aims at comparing the traditional extraction-based method with two more recent approaches (QUENCHER -QUick, Easy, New, CHEap and Reproducible- and GAR -global antioxidant response method), in order to establish their suitability in the case of beetroot. Our results indicate that the total antioxidant capacity of beetroot would be underestimated when using extraction-based procedures, since both QUENCHER and GAR methods resulted in a higher total antioxidant capacity. The effect of a thermal treatment on the total antioxidant capacity of beetroot varies among the methods evaluated and our findings suggest different compounds responsible for the total antioxidant capacity detected in each pre-processing method. Remarkably, the present study demonstrates that the traditional extraction-based method seems useful to screen for (changes in) the "bioavailable" antioxidant potential of the root.

Carotene Degradation and Isomerization during Thermal Processing: A Review on the Kinetic Aspects.

Kinetic models are important tools for process design and optimization to balance desired and undesired reactions taking place in complex food systems during food processing and preservation. This review covers the state of the art on kinetic models available to describe heat-induced conversion of carotenoids, in particular lycopene and ß-carotene. First, relevant properties of these carotenoids are discussed. Second, some general aspects of kinetic modeling are introduced, including both empirical single-response modeling and mechanism-based multi-response modeling. The merits of multi-response modeling to simultaneously describe carotene degradation and isomerization are demonstrated. The future challenge in this research field lies in the extension of the current multi-response models to better approach the real reaction pathway and in the integration of kinetic models with mass transfer models in case of reaction in multi-phase food systems.

Process-Structure-Function Relations of Pectin in Food.

Pectin, a complex polysaccharide rich in galacturonic acid, has been identified as a critical structural component of plant cell walls. The functionality of this intricate macromolecule in fruit- and vegetable-based-derived products and ingredients is strongly determined by the nanostructure of its most abundant polymer, homogalacturonan. During food processing, pectic homogalacturonan is susceptible to various enzymatic as well as nonenzymatic conversion reactions modifying its structural and, hence, its functional properties. Consequently, a profound understanding of the various process-structure-function relations of pectin aids food scientists to tailor the functional properties of plant-based derived products and ingredients. This review describes the current knowledge on process-structure-function relations of pectin in foods with special focus on pectin's functionality with regard to textural attributes of solid plant-based foods and rheological properties of particulated fruit- and vegetable-derived products. In this context, both pectin research performed via traditional, ex situ physicochemical analyses of fractionated walls and isolated polymers and pectin investigation through in situ pectin localization are considered.

Contributions of Nearly-Degenerate States to the Photoelectron Spectra of the Vanadium Dicarbide Anion.

A theoretical study by using a wide variety of quantum chemical methods has been carried out to investigate the nature of the ionization processes that are responsible for the experimental observed photoelectron spectra of the anionic VC2- stoichiometry. In agreement with previous studies, the most stable structures for the anionic and neutral vanadium dicarbide species were unambiguously found to be cyclic isomers. However, concerning the nature of the ground state of the anionic cluster there appear to be two candidates that are nearly degenerate. Only by considering both these anionic states as initial states could a substantial novel and complete assignment for the observed anion photoelectron spectra be proposed. A thorough analysis of the electronic structures not only allows us to distinguish the one-electron processes but also enables to disclose their natures. All the lower binding energy bands involve ionizations out of a dominant V+ orbital. Opposed, the higher positioned bands are the outcome of an electron detachment out of the C22- ligand 3σg orbital. Finally, the experimentally observed vibrational progressions in the photoelectron spectra of VC2- were simulated on the basis of harmonic frequency analyses at the B3LYP level and the derived Franck-Condon factors.

Enzymatic cell wall degradation of high-pressure-homogenized tomato puree and its effect on lycopene bioaccessibility.

BACKGROUND: High-pressure homogenization disrupts cell structures, assisting carotenoid release from the matrix and subsequent micellarization. However, lycopene bioaccessibility of tomato puree upon high-pressure homogenization is limited by the formation of a process-induced barrier. In this context, cell wall-degrading enzymes were applied to hydrolyze the formed barrier and enhance lycopene bioaccessibility. RESULTS: The effectiveness of the enzymes in degrading their corresponding substrates was evaluated (consistency, amount of reducing sugars, molar mass distribution and immunolabeling). An in vitro digestion procedure was applied to evaluate the effect of the enzymatic treatments on lycopene bioaccessibility. Enzymatic treatments with pectinases and cellulase were proved to effectively degrade their corresponding cell wall polymers; however, no further significant increase in lycopene bioaccessibility was obtained. CONCLUSION: A process-induced barrier consisting of cell wall material is not the only factor governing lycopene bioaccessibility upon high-pressure homogenization.

Geometric and Electronic Structures for MnS2(-/0) Clusters by Interpreting the Anion Photoelectron Spectrum with Quantum Chemical Calculations.

Geometric and electronic structures of linear SMnS, cyclic η(2)-MnS2, and linear η(1)-MnS2 isomers of MnS2(-) clusters have been investigated with B3LYP, CCSD(T), and NEVPT2 methods. The ground state of the anionic cluster is determined as (5)Πg of the linear SMnS(-) isomer, while the ground state of the neutral cluster may be either the (4)Σg(-) of the same isomer or the (6)A1 of the η(2)-MnS2 cluster. The experimental photoelectron spectrum of the MnS2(-) cluster is interpreted by contributions of these two isomers. The high-intensity band at a binding energy of 2.94 eV is attributed to the (5)Πg → (4)Σg(-) transition between the linear SMnS(-/0) clusters. The lower energy feature in the spectrum at binding energies between 1.9 and 2.8 eV and exhibiting a low intensity, is ascribed to electron detachments within the less stable η(2)-MnS2(-/0) clusters. Ionizations from the lowest energy (7)A1 state of this isomer to the neutral (6)A1, (6)A2, (8)A2, and (6)B2 states are responsible for this part of the spectrum. The extreme low intensity part between 1.3 and 1.9 eV can be due to excited states of either SMnS(-) or η(2)-MnS2(-).

A Review on the Relationships between Processing, Food Structure, and Rheological Properties of Plant-Tissue-Based Food Suspensions.

Nowadays, there is much interest in controlling the functional properties of processed fruit- and vegetable-derived products, which has stimulated renewed research interest in process-structure-function relations. In this review, we focus on rheology as a functional property because of its importance during the entire production chain up to the moment of consumption and digestion. This review covers the literature of the past decade with respect to process-structure-rheology relations in plant-tissue-based food suspensions. It became clear that the structure of plant-tissue-based food suspensions, consisting of plant-tissue-based particles in an aqueous serum phase, is affected by many unit operations (for example, heat treatment) and that also the sequence of unit operations can have an effect on the final structural properties. Furthermore, particle concentration, particle size, and particle morphology were found to be key structural elements determining the rheological properties of these suspensions comprising low amounts of starch and serum pectin. Since the structure of plant-tissue-based products was shown to be changed during processing, rheological parameters of these products were simultaneously altered. Therefore, this review also comprises a discussion of the effect on rheological properties of the most relevant processing steps in the production of plant-tissue-based products. Linking changes in rheology due to processing with process-induced alterations in structural characteristics turned out to be quite intricate. The current knowledge on process-structure-function relations can form the basis for future improved and novel food process and product design.

Quantitative assessment of molecular, microstructural, and macroscopic changes of red kidney beans (Phaseolus vulgaris L.) during cooking provides detailed insights in their cooking behavior.

Quantitative changes at different length scales (molecular, microscopic, and macroscopic levels) during cooking were evaluated to better understand the cooking behavior of common beans. The microstructural evolution of presoaked fresh and aged red kidney beans during cooking at 95 °C was quantified using light microscopy coupled with image analysis. These data were related to macroscopic properties, being hardness and volume changes representing texture and swelling of the beans during cooking. Microstructural properties included the cell area (Acell), the fraction of intercellular spaces (%Ais), and the fraction of starch area within the cells (%As/c), reflecting respectively cell expansion, cell separation, and starch swelling. A strong linear correlation between hardness and %Ais (r = -0.886, p = 0.07), along with a significant relative change in %Ais (∼5 times), suggests that softening is predominantly due to cell separation rather than cell expansion. Regarding volume changes, substantial cell expansion (Acell increased by ∼1.5 times) during the initial 30 min of cooking was greatly associated with the increase in the cotyledon volume, while the significance of cell separation became more prominent during the later stages of cooking. Furthermore, we found that the seed coat, rather than the cotyledon, played a major role in the swelling of whole beans, which became less pronounced after aging. The macroscopic properties did not correlate with %As/c. However, the evolution of %As/c conveyed information on the swelling of the starch granules during cooking. During the initial phase, the starch granule swelling mainly filled the cells, while during the later phase, the further swelling was confined by the cell wall. This study provides strong microscopic evidence supporting the direct involvement of the cell wall/ middle lamella network in microstructural changes during cooking as affected by aging, which is in line with the results of molecular changes.