Plant Cell Walls and Food Quality

Biological factors and production challenges drive significant UK fruit and vegetable loss

BACKGROUND

Food loss and waste estimates are highly inconsistent as a result of methodological and systemic differences. Additionally, the absence of in-depth evidence surrounding the biological drivers of food loss and waste precludes targeted mitigation action. To address this challenge, we undertook a metanalysis utilising a systematic literature review combined with industry stakeholder surveys to examine the incidence of food loss and waste in the UK fruit and vegetable supply chain between primary production and retail.

RESULTS

We estimated that 37% of fruit and vegetables, equivalent to 2.4 Mt of produce, is lost between production and sale. In the UK, primary production is the main stage responsible for these losses (58%), and is dominated by four crops (apple, onion, carrot and potato), which contribute 71% of total food loss and waste. Quality and supply/demand mismatch are the core drivers, combined with limited ability to control postharvest quality decline as a result of technical or economic barriers.

CONCLUSIONS

Innate biological mechanisms contribute to, and detract from, marketable quality generating food loss risks where these cannot be adequately modified or controlled. Through climate change effects, reduced pesticide availability, changing consumer behaviour and increased pressure to reduce resource/energy inputs during pre- and postharvest handling, food loss and waste risk is likely to increase in the short term unless targeted, coordinated action is taken to actively promote its mitigation. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Impact of chickpea hummus on postprandial blood glucose, insulin and gut hormones in healthy humans combined with mechanistic studies of food structure, rheology and digestion kinetics

Slowing the rate of carbohydrate digestion leads to low postprandial glucose and insulin responses, which are associated with reduced risk of type 2 diabetes. There is increasing evidence that food structure plays a crucial role in influencing the bioaccessibility and digestion kinetics of macronutrients. The aims of this study were to compare the effects of two hummus meals, with different degrees of cell wall integrity, on postprandial metabolic responses in relation to the microstructural and rheological characteristics of the meals. A randomised crossover trial in 15 healthy participants was designed to compare the acute effect of 27 g of starch, provided as hummus made from either intact chickpea cells (ICC) or ruptured chickpea cells (RCC), on postprandial metabolic responses. In vitro starch digestibility, microstructural and rheological experiments were also conducted to evaluate differences between the two chickpea hummus meals. Blood insulin and GIP concentrations were significantly lower (P < 0.02, P < 0.03) after the consumption of the ICC meal than the meal containing RCC. In vitro starch digestion for 90 min was slower in ICC than in RCC. Microscopic examination of hummus samples digested in vitro for 90 min revealed more intact chickpea cells in ICC compared to the RCC sample. Rheological experiments showed that fracture for ICC hummus samples occurred at smaller strains compared to RCC samples. However, the storage modulus for ICC was higher than RCC, which may be explained by the presence of intact cells in ICC. Food structure can affect the rate and extent of starch bioaccessibility and digestion and may explain the difference in the time course of metabolic responses between meals. The rheological properties were measured on the two types of meals before ingestion, showing significant differences that may point to different breakdown mechanisms during subsequent digestion. This trial was registered at clinicaltrial.gov as NCT03424187.

Development and Evaluation of Calcium-Fortified Multi-Millet Biscuits: A Nutritious Alternative to Refined Wheat Flour

Millet products have garnered global recognition for their exceptional nutritional profile, appealing to various age demographics, and, therefore, fortifying such products with minerals can ensure nutritional security. This research explores the feasibility of utilizing millet as a substitute for refined wheat flour in biscuit production. Three distinct millet varieties were investigated: finger, pearl, and buckwheat. Employing response surface methodology (RSM), the optimal ratio of these flours was determined, resulting in a blend of 1.5:1:1, respectively. The optimized multi-millet biscuits were further enhanced with calcium fortification and subjected to comprehensive physico-chemical analysis. Proximate composition analysis revealed favorable levels of protein (5.472 ± 0.31%), ash (2.80 ± 0.57 g/100 g), and energy density (5.8015 ± 0.004 kcal/g), indicating a significantly higher protein content, enriched mineral profile, and high energy density as compared to refined wheat flour products. Sensory evaluation encompassing attributes such as color and texture and organoleptic assessment using a nine-point hedonic scale demonstrated favorable acceptance. Additionally, the overall acceptability of the biscuits remained consistently high throughout storage, ranging from 8.263 ± 0.65 (day 0) to 8.053 ± 0.85 (day 14). This study underscores the potential of multi-millet biscuits as a nutritious and palatable alternative to traditional wheat-based snacks, offering an avenue for diversifying dietary options and promoting healthier food choices.

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.

The effects of carrot shape and oral processing behaviour on bolus properties and β-carotene bioaccessibility of raw carrots

The aim of this study was to investigate the effects of carrot shape (cube vs. julienne) and oral processing behaviour, specifically chewing time, on bolus properties and bioaccessibility of β-carotene in raw carrots. Participants (n = 20) consumed raw carrot cubes (15 × 15 × 15 mm, 4.2 g/bite) and raw carrot julienne (2 × 3 × 90 mm, 4.2 g/bite) with normal (cube: 20 s/bite; julienne: 28 s/bite) and short (cube: 10 s/bite; julienne: 14 s/bite) chewing time. Expectorated boli were collected and characterized for number and mean area of carrot bolus particles. The proportion of easily extractable β-carotene of the carrot bolus was taken as an approximate indicator of the potentially bioaccessible β-carotene. Longer chewing time resulted in significantly more and smaller carrot bolus particles, larger particle surface area (p < 0.01) and higher proportion of easily extractable β-carotene than shorter chewing of raw carrots of both shapes (Cube_Normal vs. Cube_Short: 29 ± 7 % vs. 23 ± 7 %; Julienne_Normal vs. Julienne Short: 31 ± 8 % vs. 26 ± 6 %, p < 0.05). Carrot shape significantly influenced number and size of bolus particles (p < 0.01) with carrot julienne generating more and smaller carrot bolus particles than carrot cubes. These differences in bolus properties between carrot julienne and cubes did not influence the proportion of easily extractable β-carotene (p > 0.05). We conclude that differences in oral processing behaviour and the corresponding differences in bolus properties produce only modest differences in β-carotene bioaccessibility of raw carrots regardless of carrot shape.

Salt adopted in soaking solution controls the yield and starch digestion kinetics of intact pulse cotyledon cells

Intact cellular powders have gained attention as a functional ingredient due to their lower glycemic response and potential benefits in colon. The isolation of intact cells in the laboratory and pilot plant settings is mainly achieved through thermal treatment with or without the use of limited salts. However, the effects of salt type and concentration on cell porosity, and their impact on the enzymic hydrolysis of encapsulated macro-nutrients such as starch, have been overlooked. In this study, different salt-soaking solutions were used to isolate intact cotyledon cells from white kidney beans. The use of Na₂CO₃ and Na₃PO₄ soaking treatments, with high pH (11.5-12.7) and high amount of Na ion (0.1, 0.5 M), greatly improved the yield of cellular powder (49.6-55.5 %), due to the solubilization of pectin through β-elimination and ion exchange. Intact cell walls serve as a physical barrier, significantly reducing the susceptibility of cell to amylolysis when compared to white kidney bean flour and starch counterparts. However, the solubilization of pectin may facilitate enzyme access into the cells by enlarging cell wall permeability. These findings provide new insights into the processing optimization to improve the yield and nutritional value of intact pulse cotyledon cells as a functional food ingredient.

Edible gum addition improves the quality of freeze-dried restructured strawberry blocks

Freeze-dried restructured strawberry blocks (FRSB) have become an increasingly popular product. In this study, the effects of six edible gums (guar gum, gelatin, xanthan gum, pectin, konjac gum, and carrageenan) on the FRSB quality were investigated. For FRSBs, compared with those in untreated samples, the 0.6 % guar gum addition increased texture profile analysis (TPA) hardness, chewiness, and puncture hardness by 29.59%, 174.86%, and 25.34%, respectively; after the 0.6% gelatin addition, the sensory evaluation sourness was reduced by 8.58%, whereas yield, TPA chewiness, and puncture hardness were increased by 3.40%, 28.62%, and 92.12%, respectively; with the 0.9% gelatin addition, the sensory evaluation sourness was reduced by 8.58%; with the 0.9% pectin addition, the yield, TPA hardness, chewiness, and puncture hardness were increased by 4.55%, 5.94%, 77.49%, and 103.62%, respectively. In summary, 0.6-0.9% pectin, gelatin, and guar gum addition are recommended to improve the main qualities of FRSBs.

Pore Evolution in Cell Walls of Food Tissue during Microwave-Assisted Drying: An In-Depth Investigation

Microwave (MW) heating is a unique approach that, unlike conduction- and convection-based heating, can provide volumetric heating. Complex microstructural changes in food materials occur because of simultaneous heat and mass transfer during drying, significantly affecting food structure and quality. Food properties, drying methods, and other drying parameters all have an impact on the microstructure of food samples, which in turn affects drying kinetics and food quality. However, no study has been undertaken to investigate the development of nano-micro-pores (NM-pores) on the cell walls and their relationship with the moisture migration mechanism. This study presents a novel investigation of the microstructural changes in food during microwave drying, with a focus on the formation of nano-micro-pores (NM-pores) on cell walls and their impact on moisture transport kinetics. The utilized hot air was maintained at a temperature of 70 °C, whereas microwave (MW) power levels of 100 W, 200 W, 300 W, and 400 W were used in microwave drying. The findings of the study indicate that the development of NM-pores occurs only during intermittent microwave drying (IMCD), while the cell wall of the food samples tends to burn or collapse in continuous microwave drying (CMD) due to the high heat generated. Additionally, no NM-pores were observed in the cell wall during convective drying. During IMCD with microwave power ranging from 100 W to 400 W, a range of pore sizes from 0.1 μm to 8.5 μm were observed. Due to the formation of NM-pores and collapses, MW drying takes around 10-20 times less time than convective drying to remove the same quantity of moisture. The effective moisture diffusivity values were found to be the highest in CMD at 4.70 × 10^-07 m²/s and the lowest in CD at 2.43 × 10^-09 m²/s. IMCD showed a moderate diffusivity of 2.45 × 10^-08 m²/s. This study investigates the formation of NM-pores on cell walls during microwave drying and their impact on moisture transport kinetics and establishes correlations between microstructure modifications and moisture migration pathways.

What are the determining factors controlling the juice yield of cider apple? A multimodal and multiscale investigation

Apple cider juice yield at harvest and after 15 and 30 days of storage durations was studied by analyzing the mechanical properties of fresh and plasmolyzed flesh, water distribution, cell wall polysaccharide composition and organization of the apples; in this study, the apple varieties used were Avrolles, Douce coetligne, Douce moen, Judor, Petit jaune. Juice yield mainly depended on the apple variety and the storage duration. Cellulose organization and cell wall pectin hydration were affected by ripening and are related to fruit firmness. Flesh viscoelastic mechanical properties were not general indications of juice yields. However, these properties helped distinguish the varieties according to flesh damage caused by ice crystals upon freezing. Cell encapsulation of the juice in the flesh contributed to lower yields. The apple variety and harvesting mode are recommended as a means to better control juice yield variations.

Optimization of Conditions for a Freeze-Dried Restructured Strawberry Block by Adding Guar Gum, Pectin and Gelatin

With its high moisture content and tender texture, fresh strawberry is very susceptible to mechanical damage and microbial infection. Drying is one of the most frequently employed methods to extend its shelf life, and freeze-dried restructured strawberry block (FRSB) is an emerging popular food. Here, in order to enhance the quality of FRSB, edible gums of guar gum, pectin, and gelatin were added and the combination was optimized using response surface methodology (RSM) with chewiness, hardness, and organoleptic evaluations of the dried sample as the response indicators. The results showed that the combination addition of 0.10% guar gum, 0.22% pectin, and 0.30% gelatin contributed to the highest comprehensive quality of the dried sample. Compared with the untreated sample, the optimal combination addition of the three edible gums resulted in a higher moisture content for the dried sample (increased by 0.8%), and increased the chewiness, hardness, and porosity by 82.04%, 27.09%, and 3.01%, respectively, while maintaining more original color and forming a denser porous microstructure. The findings in the current work will be useful for the application of edible gums in freeze-dried restructured fruits and vegetables.

Potassium Bioaccessibility in Uncooked and Cooked Plant Foods: Results from a Static In Vitro Digestion Methodology

Hyperkalemia is a major concern in chronic kidney disease and in end-stage renal disease, representing a predictor of hospitalization and mortality. To prevent and treat hyperkalemia, dietary management is of great clinical interest. Currently, the growing use of plant-based diets causes an increasing concern about potassium load in renal patients. The aim of this study was to assess the bioaccessibility of potassium in vegetables, concerning all aspects of the plants (fruit, flower, root, tuber, leaf and seed) and to what extent different boiling techniques affect potassium content and bioaccessibility of plant-based foods. Bioaccessibility was evaluated by an in vitro digestion methodology, resembling human gastro-intestinal tract. Potassium content was higher in seeds and leaves, despite it not being possible to define a common “rule” according to the type of organ, namely seed, leaf or fruit. Boiling reduced potassium content in all vegetables excluding carrot, zucchini, and cauliflower; boiling starting from cold water contributed to a greater reduction of the potassium content in potato, peas, and beans. Bioaccessibility after in vitro digestion ranged from 12 (peas) to 93% (tomato) regardless of species and organs. Higher bioaccessibility was found in spinach, chicory, zucchini, tomato, kiwi, and cauliflower, and lower bioaccessibility in peas. Potassium from leaf resulted in the highest bioaccessibility after digestion; as a whole potassium bioaccessibility in the fruits and vegetables studied was 67% on average, with differences in relation to the different organs and species. Further, considering the method of boiling to reduce potassium content, these data indicate that the effective potassium load from plant-based foods may be lower than originally expected. This supports the clinical advices to maintain a wide use of plant-based food in the management of renal patients.

Flavor and Other Quality Traits of Tomato Cultivars Bred for Diverse Production Systems as Revealed in Organic Low-Input Management

This study was conducted to determine the volatile organic compounds (VOCs) associated with fruit flavor in diverse tomato cultivars (salad and cocktail cultivars) under organic low-input production. For this objective, 60 cultivars deriving from very diverse breeding programs 1880-2015 were evaluated in 2015, and a subset of 20 cultivars was selected for further evaluation in 2016. The diversity of instrumentally determined traits, especially for VOCs concentration and sensory properties (fruit firmness, juiciness, skin firmness, sweetness, sourness, aroma, and acceptability), was investigated at two harvest dates. The evaluation of the cultivars exhibited a wide range of variation for all studied traits, with the exception of a few VOCs. Cultivar had the most important effect on all instrumentally determined traits, while the influence of cultivar × harvest date × year interaction was significant for 17 VOCs, but not for total soluble solid (TSS) and titratable acidity (TA). The VOCs with the highest proportion (>8%) were hexanal, 6-methyl-5-heptene-2-one, 2-isobutylthiazole, and (E)-2-hexenal, which were identified in all cultivars. Twelve VOCs significantly correlated with one or more sensory attributes and these VOCs also allowed differentiation of the fruit type. Among these VOCs, phenylethyl alcohol and benzyl alcohol positively correlated with acceptability in the cocktail cultivars, whereas 2-isobuthylthiazole and 6-methyl-5-hepten-2-ol negatively correlated with acceptability in the salad cultivars. As a result of this study, organic breeders are recommended to use cultivars from a wide range of breeding programs to improve important quality and agronomic traits. As examples, salad tomatoes "Campari F1", "Green Zebra", and "Auriga", as well as cocktail tomatoes "Supersweet 100 F1", "Sakura F1", and "Black Cherry" showed higher scores for the sensory attributes aroma and acceptability under organic low-input growing conditions. It remains a challenge for breeders and growers to reduce the trade-off of yield and quality.

Textural Properties of Chinese Water Chestnut (Eleocharis dulcis) during Steam Heating Treatment

Chinese water chestnut (CWC) has become one of the most popular foods in China. The textural properties of food contribute considerably to consumer preferences. Fresh fruits and vegetables are normally softened after thermal treatment. However, CWC retains most of its crispness and hardness after steaming. To explore the relationship between thermal processes and sensory changes, a method for measuring the texture of CWC is warranted. This study aimed to examine the textural properties of CWC subjected to varying degrees of thermal treatments using instrumental and sensory methods. Instrumental tests included the shear force test and puncture test, while trained panelists assessed the sensory attributes. Two sensory attributes were selected for evaluation: crispness and hardness. The results indicated that with the extension of thermal treatment time, the crispness and hardness of CWC decreased slightly, while cells and starch grains were damaged. Sensory results showed a significant correlation with shear force index (slope of rising curve) (p < 0.05) and puncture index (slope of rising curve, slope of descending curve and compression work) (p < 0.05). Thereafter, the instrumental tests parameters could be used to establish regression models for predicting crispness and hardness and controlling the quality of CWC products.

Nutraceutical Concepts and Dextrin-Based Delivery Systems

Nutraceuticals are bioactive or chemical compounds acclaimed for their valuable biological activities and health-promoting effects. The global community is faced with many health concerns such as cancers, cardiovascular and neurodegenerative diseases, diabetes, arthritis, osteoporosis, etc. The effect of nutraceuticals is similar to pharmaceuticals, even though the term nutraceutical has no regulatory definition. The usage of nutraceuticals, to prevent and treat the aforementioned diseases, is limited by several features such as poor water solubility, low bioavailability, low stability, low permeability, low efficacy, etc. These downsides can be overcome by the application of the field of nanotechnology manipulating the properties and structures of materials at the nanometer scale. In this review, the linear and cyclic dextrin, formed during the enzymatic degradation of starch, are highlighted as highly promising nanomaterials- based drug delivery systems. The modified cyclic dextrin, cyclodextrin (CD)-based nanosponges (NSs), are well-known delivery systems of several nutraceuticals such as quercetin, curcumin, resveratrol, thyme essential oil, melatonin, and appear as a more advanced drug delivery system than modified linear dextrin. CD-based NSs prolong and control the nutraceuticals release, and display higher biocompatibility, stability, and solubility of poorly water-soluble nutraceuticals than the CD-inclusion complexes, or uncomplexed nutraceuticals. In addition, the well-explored CD-based NSs pathways, as drug delivery systems, are described. Although important progress is made in drug delivery, all the findings will serve as a source for the use of CD-based nanosystems for nutraceutical delivery. To sum up, our review introduces the extensive literature about the nutraceutical concepts, synthesis, characterization, and applications of the CD-based nano delivery systems that will further contribute to the nutraceutical delivery with more potent nanosystems based on linear dextrins.

Hydrothermal carbonization and Liquefaction: differences, progress, challenges, and opportunities

Thermochemical processes including hydrothermal technology are gaining research interest as a potentially green method for deconstructing biomass into platform chemicals or energy carriers. Hydrothermal liquefaction (HTL) and Hydrothermal Carbonization (HTC) are advantageous because of their enhanced process performance while being environmentally friendly and technologically innovative. However, after a deep review, several works have shown a misunderstanding between HTL and HTC concepts. Therefore, this review advances understanding on the main differences and gaps found between HTL and HTC in terms of operation parameters, technical issues, and main products. Furthermore, environmental and techno-economic assessments (TEA) were presented to appraise the environmental sustainability and economic implications of these techniques. Perspectives and challenges are presented and the integration approaches of hydrothermal valorization pathways and biorefining are explored.

Effect of home processing methods on the levels of heavy metal contaminants in four food crops grown in and around two mining towns in Ghana

Unregulated small-scale mining activities, by young untrained men using some poisonous chemicals, occur in several agricultural forest belts in Ghana. These activities contaminate water bodies in these areas, which happen to be the main farming sites where food crops are intensively cultivated. The presence of these heavy metal contaminants in popular food staples is therefore worrying because of its adverse health implications. Previous studies have shown that processing is able to decrease the concentrations of heavy metals in foods. This study investigated the effectiveness of home processing methods (boiling, frying and roasting) in significantly reducing the levels of heavy metal contaminants in food crops grown in and around two main mining centers in Ghana. The heavy metals contaminants analyzed for, were Arsenic (As), Cadmium, (Cd), lead (Pb), Manganese (Mn), and Mercury (Hg), determined using atomic absorption spectrometry (AAS) and inductively-coupled plasma mass spectrometry (ICP-MS). From the data, the average daily intakes of the heavy metals and the associated long-term health risks to consumers were assessed. Unprocessed samples from Akwatia had higher levels of contaminants than those from Obuasi. Levels of Mn, Pb and As recorded in all unprocessed samples were higher compared to WHO permissible limits in foods. The levels showed a decreasing trend in the processed samples; with the lowest As and Pb content recorded after frying and boiling. The study showed that roasting allowed for the least reduction in the heavy metal contaminations in the four food crops. The levels of Cd in both processed and unprocessed samples were within safe WHO specifications. Except for Pb in unprocessed cassava, boiled cassava and unprocessed plantain and Hg (unprocessed yam and roasted yam), the hazard indices of all metals in all food crops were less than one and posed no risk to consumers. The study therefore reveals that the normal home processing methods are able to reduce the levels of heavy metal contaminants found in cassava, cocoyam, plantain and yam considerably.

Microstructural and Texturizing Properties of Partially Pectin-Depleted Cell Wall Material: The Role of Botanical Origin and High-Pressure Homogenization

In the current study, the texturizing properties of partially pectin-depleted cell wall material (CWM) of apple, carrot, onion and pumpkin, and the potential of functionalization by high-pressure homogenization (HPH) were addressed. This partially pectin-depleted CWM was obtained as the unextractable fraction after acid pectin extraction (AcUF) on the alcohol-insoluble residue. Chemical analysis was performed to gain insight into the polysaccharide composition of the AcUF. The microstructural and functional properties of the AcUF in suspension were studied before HPH and after HPH at 20 and 80 MPa. Before HPH, even after the pectin extraction, the particles showed a cell-like morphology and occurred separately in the apple, onion and pumpkin AcUF and in a clustered manner in the carrot AcUF. The extent of disruption by the HPH treatments at 20 and 80 MPa was dependent on the botanical origin. Only for the onion and pumpkin AcUF, the water binding capacity was increased by HPH. Before HPH, the texturizing potential of the AcUFs was greatly varying between the different matrices. Whereas HPH improved the texturizing potential of the pumpkin AcUF, no effect and even a decrease was observed for the onion AcUF and the apple and carrot AcUF, respectively.

Genomic and transcriptomic analyses of Citrus sinensis varieties provide insights into Valencia orange fruit mastication trait formation

Valencia orange (Citrus sinensis Osbeck) (VO) is a type of late-ripening sweet orange whose ripening occurs 4 to 5 months later than that of the mid-ripening common sweet orange (CO). Notably, the mastication trait of VO fruit is inferior to that of CO fruit. To date, how inferior pulp mastication trait forms in VO has not been determined. In this study, 13 VO varieties and 12 CO varieties were subjected to whole-genome resequencing. A total of 2.98 million SNPs were identified from 25 varieties, and a SNP molecular marker was developed to distinguish VO and CO. Moreover, 144 and 141 genes identified by selective sweep analysis were selected during VO and CO evolution, respectively. Based on gene functional enrichment analysis, most of the selected VO genes were related to the stress response and lignin biosynthesis. Simultaneously, we comparatively analyzed the transcriptome profiles of peel and pulp tissues among three VO varieties and three CO varieties, and the results demonstrated differences in lignin biosynthesis between VO and CO fruits. Furthermore, coexpression network analysis was performed to identify hub genes of lignin-related and variety-specific networks, which included CsERF74, CsNAC25, CsHSFB3, CsSPL4/13, etc. Overall, this study provides important insights into the mastication trait formation of Valencia orange fruit.

Chemical and structural quality traits during postharvest ripening regulated by chromosome segments from a wild relative of tomato Solanum pennellii IL4-2 and IL5-1

Tomato is usually harvested at an early ripening stage with high firmness suitable for storage and transportation but lacks many quality parameters such as sugars, organic acids, and phenolics. In a recent study, we have selected introgression lines (ILs) IL4-2 and IL5-1, developed from a cross between the Solanum pennellii and the Solanum lycopersicum M82, that exhibit differentiated postharvest shelf-life characteristics in the fruit compared to M82 and the rest of the ILs. Here, we first structurally and biochemically characterized IL4-2, IL5-1, and their parent M82 to decipher the cell wall mechanistic difference between soft (IL4-2) and firm (IL5-1) lines at two postharvest ripening periods. Generally, IL4-2 had more active cell wall modifications in terms of ripening-related gene expression, water-soluble pectin, and cell wall structure under the microscope, which probably makes this line softer than IL5-1. We also evaluated these lines based on commercial quality parameters, sugars, phenolics, organic, and amino acids to gain insight into their commercial and functional quality and reveal noticeable differences. In summary, the contribution of the S. pennellii IL5-1 and IL4-2 to the shelf life of the tomato was structurally characterized, and the component differences meeting the quality criteria were revealed.

The Structure and Composition of Extracted Pectin and Residual Cell Wall Material from Processing Tomato: The Role of a Stepwise Approach versus High-Pressure Homogenization-Facilitated Acid Extraction

In literature, different pectin extraction methods exist. In this study, two approaches starting from the alcohol-insoluble residue (AIR) of processing tomato are performed in a parallel way to facilitate the comparison of pectin yield and the compositional and structural properties of the extracted pectin and residual cell wall material obtained. On the one hand, pectin is extracted stepwise using hot water, chelating agents and low-alkaline conditions targeting fractionation of the pectin population. On the other hand, an industrially relevant single-step nitric acid pectin extraction (pH 1.6) is performed. In addition to these conventional solvent pectin extractions, the role of high-pressure homogenization (HPH) as a physically disruptive treatment to facilitate further pectin extraction from the partially pectin-depleted fraction obtained after acid extraction is addressed. The impact of HPH on the pectin cell wall polysaccharide interactions was shown as almost two thirds of the residual pectin were extractable during the subsequent extractions. For both extraction approaches, pectin obtained further in the sequence was characterized by a higher molecular mass and a higher amount of rhamnogalacturonan I domains. The estimated hemicellulose and cellulose content increased from 56 mol% for the AIR to almost 90 mol% for the final unextractable fractions of both methods.

Properties of Biocomposites from Rapeseed Meal, Fruit Pomace and Microcrystalline Cellulose Made by Press Pressing: Mechanical and Physicochemical Characteristics

This paper presents the results of research on biocomposites made of the mixture of post-extraction rapeseed meal, microcrystalline cellulose and various fruit pomace (chokeberry, blackcurrant, apple and raspberry pomace). The biocomposites were made in the process of mechanical thickening by means of a heated mould (die and stamp) which is located between two heating elements installed on a hydraulic press. The presented research combines mechanical engineering and material engineering issues. The physical and mechanical tests of obtained biocomposites included mechanical strength measurements, thermogravimetric analyses (TGA), colour change tests and scanning electron microscopic (SEM) tests of the internal structure after breaking the sample. In addition, Fourier transform infrared spectroscopy (FTIR) tests were carried out. Generally, the bend tests and Young's modulus were significantly increased, for example, biocomposites with an addition of chokeberry pomace had the flexural strength higher by approximately 25% in relation to the primary sample. Furthermore, it is interesting to note the increase of water contact angle of these biocomposites by 40% in relation to the primary sample. The research indicates the potential for using fruit pomace for the needs of biocomposite production.

Freshness Quality and Shelf Life Evaluation of the Seaweed Ulva rigida through Physical, Chemical, Microbiological, and Sensory Methods

In Europe, the consumption of seaweeds and derived products has increased in recent years, due to the expansion of Asian cuisine and the emergence of many top-level chefs. Often in collaboration with scientists, many have initiated a new gastronomy using algae. However, little is known about the quality and degree of freshness of seaweeds for direct consumption or fresh use. For this reason, different analytical methods were applied to test sea vegetables and other marine products. These methods included physical (a_w, pH, color, and texture), chemical (total volatile base nitrogen, TVB-N; and trimethylamine, TMA-N) parameters, microbiological count, and sensory evaluation. In this study, freshness quality and shelf life of the green seaweed Ulva rigida (UR) was evaluated during a 12-day period, stored at 4 and 16 °C. The parameters that proved to be most useful for evaluating its freshness were the TVB, TMA, microbiological, and sensory analyses. The physicochemical and microbiological parameters established a shelf life of UR of 6 days for a storage temperature of 16 °C and up to 10 days for a storage temperature of 4 °C. The changes that UR undergoes during its storage from the sensory point of view are more pronounced than those produced from the physicochemical point of view, which can condition its applications.

Dietary fiber components, microstructure, and texture of date fruits (Phoenix dactylifera, L.)

Date fruits vary widely in the hardness of their edible parts and they are classified accordingly into soft, semi-dry, and dry varieties. Fruit texture, a significant parameter in determining consumer acceptance, is related to the tissue structure and chemical composition of the fruit, mainly the ratio of sucrose to reducing sugars. This study aimed to understand the relationship between the chemical composition, microstructure, and texture profile of 10 major Emirati date fruits. The soluble sugars, glucose and fructose, represent ca 80 g/100 g of the fruits on the basis of dry weight (DW) while the dietary fiber contents varied 5.2-7.4 g/100 dg D.W. with lignin being the main determinant of the variability. The textures of the samples were studied using instrumental texture profile analysis. While no correlation was found between the soluble sugar and texture parameters in this study, the different fiber constituents correlated variably with the different parameters of date fruit texture. Lignin, arabinoxylan, galactomannan, and pectin were found to correlate significantly with fruit hardness and the related parameters, gumminess and chewiness. Both lignin and arabinoxylan correlated with resilience, and arabinoxylan exhibited a strong correlation with cohesiveness.

Genetic variability of cooking time in dry beans (Phaseolus vulgaris L.) related to seed coat thickness and the cotyledon cell wall

Dry beans are an affordable, nutritious food that often require long cooking times. Storage time and conditions, growing environment, and genotype influence cooking times. Little is known about factors underlying genetic variation for cooking time. Using fast and slow cooking genotypes from four different seed types (brown, cranberry, red mottled, yellow), the objectives of this study were to (1) characterize genetic variability for cooking time across multiple soaking time points; (2) determine the roles of seed coat and cotyledon cell wall physical traits in genetic variability for cooking time; and (3) identify seed coat and cotyledon cell wall compositional differences associated with genetic variability for cooking time. Genotypes were evaluated for cooking time on unsoaked beans and beans soaked for 3, 6, 12, 18, and 24 h. Cooking times were sharply reduced after 3 h of soaking and plateaued after 6 h of soaking. Interestingly, the genotypes in each pair that cooked faster when soaked did not necessarily cook faster when unsoaked. Greater seed coat percentage, cotyledon cell wall thickness, total and insoluble whole seed dietary fiber, and insoluble cotyledon cell wall isolate were genotypic factors associated with longer cooking times of soaked beans. Thicker seed coat macrosclereid- and osteosclereid-layers were genotypic factors associated with longer cooking times of unsoaked beans. These findings suggest that cotyledon cell wall thickness and composition have a significant role in genetic variability for cooking time of soaked beans and seed coat layer thickness relates to the genetic variability for cooking time of unsoaked beans.

Changes in cell wall neutral sugar composition related to pectinolytic enzyme activities and intra-flesh textural property during ripening of ten apricot clones

The changes of texture and cell wall characteristics of apricot were investigated in ten clones at two maturity stages. Fruit firmness, cell wall composition and enzyme activity of three apricot flesh zones were analysed. The AIS (alcohol-insoluble solids) were characterised by high amounts of uronic acid (179-300 mg g^-1 AIS) and relatively high amounts of cellulosic glucose (118-214 mg g^-1 AIS). The methylesterification degree varied significantly among the different clones ranging from 58 to 97 in Ab 5 and Mans 15 respectively. Conversely to zones firmness, enzymatic activity was higher in pistil followed by equatorial and peduncle zones. The ripening effect has been observed in firmness evolution according to enzymatic activity. This correlation allowed a classification of clones depending on softening. Among studied clones, Ab 5, Marouch 16, Mans 15 and Cg 2 were less influenced by softening and have the advantage of a technological valorisation for the processing industry.

Impact of Ohmic Heating and High Pressure Processing on Qualitative Attributes of Ohmic Treated Peach Cubes in Syrup

Stabilization of ohmic pretreated peach cubes (ohm) in syrup, representative of semifinished fruit products, was finalized by ohmic heating (OHM) and high pressure processing (HPP), proposed respectively as thermal and nonthermal pasteurization, in comparison to a conventional pasteurization treatment (DIM). The samples were then studied in terms of histological, physical (dimensional distribution, tenderometry, texture, viscosity of syrup and colour), chemical (total phenolic and ascorbic acid content), and sensorial (triangle test) properties. Severe modifications of the cell walls were observed in ohm-DIM and ohm-OHM samples, with swelling and electroporation, respectively. From chemical analyses, significant reduction of ascorbic acid and simultaneous increase of total phenolics content were observed for ohm-DIM and ohm-OHM, probably in relation to the cell wall damages. ohm-HPP showed the best preservation of the dimensional characteristics and hardness, followed by ohm-OHM and ohm-DIM. In addition, textural and colour parameters evidenced similar results, with ohm-HPP as the less different from ohm. Finally, the sensorial analysis confirmed ohm-HPP and ohm-OHM samples as the most similar to ohm as well as the most appreciated in terms of colour and consistency.

Inhibition of fruit softening by cold plasma treatments: affecting factors and applications

Softening is a common phenomenon of texture changes associated with plant cell walls, inducing a decrease in the quality of fruit. Inhibiting the softening is effective to extend the shelf life of fruit. Cold plasma (CP), as a novel nonthermal technology, has been applied to keep the freshness of the fruit. This review centers on applying cold plasma treatments to the inhibition of fruit softening. Different pathways for inhibiting fruit softening by CP treatments, including maintenance of fruit firmness, reduction in the activities of enzymes, inactivation of fungal pathogens and lowering of respiration rates, are discussed. The biochemistry of fruit softening and the fundamental of cold plasma are also presented. In general, among all postharvest technologies, cold plasma is a promising method with many advantages, showing great potential in maintaining the quality and inhibiting the softening of the fruit. Future work should focus on process optimization to achieve better results in maintaining fruit freshness, and commercial applications of cold plasma technology should also be explored.

Destructuring and restructuring of foods during gastric digestion

All foods harbor unique length scale-dependent structural features that can influence the release, transport, and utilization of macro- or micronutrients in the human gastrointestinal tract. In this regard, food destructuring and restructuring processes during gastric passage significantly influence downstream nutrient assimilation and feelings of satiety. This review begins with a synopsis of the effects of oral processing on food structure. Then, stomach-centric factors that contribute to the efficacy of gastric digestion are discussed, and exemplified by comparing the intragastric de- and restructuring of a number of common foods. The mechanisms of how intragastric structuring influences gastric emptying and its relationship to human satiety are then discussed. Finally, recently developed, non-destructive instrumental approaches used to quantitively and qualitatively characterize food behavior during gastric destructuring and restructuring are described.

Plant Cell Walls: Impact on Nutrient Bioaccessibility and Digestibility

Cell walls are important structural components of plants, affecting both the bioaccessibility and subsequent digestibility of the nutrients that plant-based foods contain. These supramolecular structures are composed of complex heterogeneous networks primarily consisting of cellulose, and hemicellulosic and pectic polysaccharides. The composition and organization of these different polysaccharides vary depending on the type of plant tissue, imparting them with specific physicochemical properties. These properties dictate how the cell walls behave in the human gastrointestinal tract, and how amenable they are to digestion, thereby modulating nutrient release from the plant tissue. This short narrative review presents an overview of our current knowledge on cell walls and how they impact nutrient bioaccessibility and digestibility. Some of the most relevant methods currently used to characterize the food matrix and the cell walls are also described.