Functional and sensory properties of phenolic compounds from unripe grapes in vegetable food prototypes

Plasmopara viticola effector PvCRN20 represses the import of VvDEG5 into chloroplasts to suppress immunity in grapevine

Chloroplasts play a crucial role in plant defense against pathogens, making them primary targets for pathogen effectors that suppress host immunity. This study characterizes the Plasmopara viticola CRN-like effector, PvCRN20, which interacts with DEG5 in the cytoplasm but not with its interacting protein, DEG8, which is located in the chloroplast. By transiently overexpressing in tobacco leaves, we show that PvCRN20 could inhibit INF1- and Bax-triggered cell death. Constitutive expression of PvCRN20 suppresses the accumulation of reactive oxygen species (ROS) and promotes pathogen colonization. PvCRN20 reduces DEG5 entry into chloroplasts, thereby disrupting DEG5 and DEG8 interactions in chloroplasts. Overexpression of VvDEG5 and VvDEG8 induces ROS accumulation and enhances grapevine resistance to P. viticola, whereas knockout of VvDEG8 represses ROS production and promotes P. viticola colonization. Consistently, ectopic expression of VvDEG5 and VvDEG8 in tobacco promotes chloroplast-derived ROS accumulation, whereas co-expression of PvCRN20 counteracted this promotion by VvDEG5. Therefore, DEG5 is essential for the virulence function of PvCRN20. Although PvCRN20 is located in both the nucleus and cytoplasm, only cytoplasmic PvCRN20 suppresses plant immunity and promotes pathogen infection. Our results reveal that PvCRN20 dampens plant defenses by repressing the chloroplast import of DEG5, thus reducing host ROS accumulation and facilitating pathogen colonization.

Effect of NaCl Pretreatment on the Relationship between the Color Characteristics and Taste of Cirsium setidens Processed Using a Micro-Oil-Sprayed Thermal Air Technique

Cirsium setidens is commonly used as a food ingredient, and it is typically stored and distributed in a dried form to prolong its shelf life. In a previous study, a micro-oil-sprayed thermal air (MOTA) technique was developed, which effectively enhanced the rehydration properties and improved the color characteristics of Cirsium setidens after processing. Here, we investigated the relationship between the color characteristics and taste of MOTA-processed C. setidens and the effect of NaCl pretreatment, prior to processing, on the final quality of dried C. setidens. NaCl pretreatment, whether combined with the MOTA technique or not, showed improved color characteristics, in which MOTA-and NaCl+ MOTA-processed C. setidens manifested equal color characteristics. In contrast, NaCl + MOTA-processed C. setidens resulted in significantly higher values of sourness and saltiness than MOTA-processed C. setidens when the taste of the rehydrated C. setidens was examined using an electronic tongue (Astree II; Alpha MOS, Toulouse, France). Pearson correlation coefficient analysis showed that sourness and saltness were negatively correlated with Hunter a* values and positively correlated with Hunter L* and Hunter b* values, indicating that the color characteristics of dried and rehydrated C. setidens could be indicators of taste. Furthermore, the amounts of total phenol and chlorophyll were better preserved in C. setidens processed by the MOTA technique with NaCl than by the MOTA technique alone. Our data revealed that the color characteristics of dried plants are associated with the taste of processed C. setidens, and that the MOTA technique with NaCl pretreatment is a useful method for preserving health-promoting compounds during processing.

Phenolic Composition of Brazilian BRS Carmem (Muscat Belly A × BRS Rúbea) Grapes: Evaluation of Their Potential Use as Bioingredients

The BRS Carmem grape was developed as an alternative for processing juices and wines. This study aimed to determine the phenolic compounds (PC) in the edible parts of this grape from two harvests-one harvested at ideal maturation time and another when the grapes were still immature-using HPLC-DAD-ESI-MS/MS. Student's t-test was used (α = 0.05) to evaluate differences in the PC content between the edible parts and between the harvests. Both skins showed a predominance of flavonols, anthocyanins, hydroxycinnamic acids derivatives (HCAD) and stilbenes, with higher concentrations for harvest 1 than harvest 2. For both harvests (harvest 1 and harvest 2), the HCAD (mg of caftaric acid•kg fruit^-1) was higher in whole grapes (383.98 and 67.09) than in their skins (173.95 and 21.74), with a predominance of trans-caffeic acid for all samples; the flavan-3-ols and proanthocyanidins (mg of (+)-catechin•kg fruit^-1) presented higher concentrations in the seeds (flavan-3-ols: 203.20 and 182.71, proanthocyanidins: 453.57 and 299.86) than in the skins (flavan-3-ols: 1.90 and 4.56, proanthocyanidins: 37.58 and 98.92); the stilbenes concentration (µg 3-glc-resveratrol•kg fruit^-1) was higher for the seeds from harvest 2 (896.25) than those from harvest 1 (48.67). BRS Carmem grapes contain a phenolic composition complex, and still have a relevant concentration of flavonols, anthocyanins and stilbenes, even when immature.

Influence of environmental conditions on the production of nutraceuticals in Italian edible plant landraces

Autochthonous plant varieties, also referred to as landraces, represent an important genetic resource, being well-adapted to the environment in which they have been selected. Landraces usually show profiles rich in nutraceuticals, making them an effective and valuable alternative to commercial agri-products, as well as potential candidates for crop improvement programs. Basilicata region is recognized as an Italian hotspot for agrobiodiversity, due to its complex orography. Thus, this work aimed to characterize and monitor, for two successive years, the content of secondary metabolites and related antioxidant properties of seven different species, four officinal (i.e., wild fennel - Feoniculum vulgare Mill.; oregano - Origanum vulgare L.; thyme - Thymus vulgaris L.; valerian - Valeriana officinalis L.) and three fruit species (i.e., fig - Ficus carica L. cv. Dottato; sweet cherry Prunus avium L. cv. Majatica; plum - Prunus domestica L. cv. Cascavella Gialla), collected in three different sites of this region. In detail, spectrophotometric tests were performed to assess the concentration of phenolic compounds, flavonoids, and - for officinal plants - also terpenoids, together with the antiradical activity (FRAP assays). In addition, to better typify the phytocomplexes of these landraces, HPLC-DAD and GC-MS analyses were carried out. In general, officinal plants showed higher values of nutraceutical compounds and related bioactivity with respect to fruit species. The data showed how different accessions of the same species had different phytochemical profiles, according to the sampling area and the year of collection, suggesting a role for both genetic and environmental factors in determining the observed results. Therefore, the final goal of this research was also to find a possible correlation between environmental factors and nutraceutics. The greatest correlation was found in valerian, where a lower water intake seemed to lead to a higher accumulation of antioxidants, and in plum, where the flavonoid content correlated positively with high temperatures. All these outcomes contribute at valorising Basilicata landraces for their aptitude to be high-quality foods and, at the same time, promoting the preservation of the agrobiodiversity for this region.

Replacement of SO2 with an Unripe Grape Extract and Chitosan during Oak Aging: Case Study of a Sangiovese Wine

The aim of this study was to evaluate the chemical, microbiological and sensory characteristics of a Sangiovese wine aged in barrique with the addition of an unripe grape extract (UGE) as an alternative to sulfur dioxide. Three samples were considered: control wine (TQ) with free SO₂ of approximately 15 mg/L; sample A with chitosan (100 mg/L) and UGE (200 mg/L); and sample B with UGE (400 mg/L). The results achieved in this work demonstrated that the UGE, either alone or in combination with chitosan, was able to maintain the color characteristics of the Sangiovese wine and its sensory quality. Moreover, the addition of UGE contributed to an early and better stabilization of the color through the formation of polymeric pigments. The microbiological stabilization was comparable to SO₂ when UGE was used at 200 mg/L in combination with chitosan. The market survey conducted in the present study confirmed how the use of UGE as an alternative to sulfitation was positively accepted by consumers, who are increasingly attentive not only to the quality of the wines they select but also to the sustainability of the production processes from which they derive and to the fact that they are not harmful to human health.

Development and Characterization of Functional Cookies Enriched with Chestnut Shells Extract as Source of Bioactive Phenolic Compounds

Chestnut (Castanea sativa) shells (CSs), an undervalued agro-industrial biowaste, have arisen as a source of bioactive compounds with promising health-promoting effects. This study attempted, for the first time, to develop a functional food, namely cookies, using a CS extract obtained by an eco-friendly technology (subcritical water extraction). The cookies were characterized regarding their nutritional composition, total phenolic and flavonoid contents (TPC and TFC, respectively), antioxidant/antiradical activities, phenolic profile, and sensory evaluation. The results demonstrated that the CS-extract-enriched cookies were mainly composed of carbohydrates (53.92% on dry weight (dw)), fat (32.62% dw), and fiber (5.15% dw). The phenolic profile outlined by HPLC-PDA revealed the presence of phenolic acids, flavonoids, and hydrolysable tannins, attesting to the high TPC and TFC. The in vitro antioxidant/antiradical effects proved the bioactivity of the functional cookies, while the sensory evaluation unveiled excellent scores on all attributes (≥6.25). The heatmap diagram corroborated strong correlations between the TPC and antioxidant/antiradical properties, predicting that the appreciated sensory attributes were closely correlated with high carbohydrates and phenolic compounds. This study encourages the sustainable recovery of antioxidants from CSs and their further employment as an active nutraceutical ingredient in functional cookies.

Characterization of Unripe Grapes (Vitis vinifera L.) and Its Use to Obtain Antioxidant Phenolic Compounds by Green Extraction

Thinning pruning is a process in modern viticulture to improve product quality when grapes are still in the immature fruit stage. Unripe grapes, which are waste, are mostly consumed locally as verjuices to meet domestic demand. This study aims to optimize a more efficient “green” technique for the extraction of total phenolic compounds (TPC) and antioxidant capacity (AC) from three varieties of unripe grape juice by response surface method (RSM) using ultrasound-assisted extraction (UAE). The influence of temperature (25–65°C) and extraction time (5–30 min) on total phenolic content (TPC) and antioxidant capacity (DPPH and CUPRAC) was investigated. In this study, physicochemical properties, mineral composition, phenolic and organic acid components of three different verjuices were also investigated. As a result, the optimal extraction points for extraction time (12 min) and temperature (30°C) were determined. All independent variables were found to be significantly effective on TPC and AC content during UAE. Verjuices are a rich source of antioxidants, phenols, organic acids, minerals, and vitamin C. This study is expected to contribute to the evaluation of unripe grape wastes, which are very rich in bioactive components, and to increase its economic potential by expanding local production, thus contributing to sustainable agri-food processing.

Potential opportunities of thinned clusters in viticulture: a mini review

Crop thinning is a common practice performed in the vineyard consisting of whole clusters or individual fruits being removed after flowering is attained. Current studies have reported that unripe grape products as verjuice and sour grape sauce contain high content of bioactive compounds such as polyphenols, sugars, organic acids, nitrogenous compounds and sterols. This mini-review overviewed the bioactive components obtained from thinned unripe grapes such as phenolic compounds, sugars, organic acids, minerals, nitrogen compounds and sterols, and their use as antibrowning and whitening agents, natural catalysts, food preservative and food additive. In addition, their beneficial effects for human health also were reviewed, as well as the practices to maximize the extraction of antioxidant compounds. Therefore, revalorizing the waste from this management practice in viticulture can increase the vineyard sustainability and farmers' economic profits. © 2021 Society of Chemical Industry.

Comprehensive Utilization of Thinned Unripe Fruits from Horticultural Crops

Fruit thinning is a cultivation technique that is widely applied in horticulture in order to obtain high-quality horticultural crops. This practice results in the discarding of a large number of thinned unripe fruits in orchards each year, which produces a great waste of agricultural resources and causes soil pollution that may be an important reservoir for pest and plant diseases. Current studies showed that bioactive compounds such as polyphenols, organic acids, monosaccharides and starches are present in unripe fruits. Therefore, we reviewed the bioactive components obtained from thinned unripe fruits, their revalorization for the food industry, their beneficial effects for human health and the methods for obtaining these components. We also performed a calculation of the costs and benefits of obtaining these bioactive compounds, and we proposed future research directions. This review provides a reference for the effective utilization and industrial development of thinned unripe fruits obtained from horticultural crops. Furthermore, revalorizing the waste from this cultural practice may increase the economic benefits and relieve the environmental stress.

Characterisation of Extracts Obtained from Unripe Grapes and Evaluation of Their Potential Protective Effects against Oxidation of Wine Colour in Comparison with Different Oenological Products

Unripe grapes (UGs) are a waste product of vine cultivation rich in natural antioxidants. These antioxidants could be used in winemaking as alternatives to SO2. Three extracts were obtained by maceration from Viognier, Merlot and Sangiovese UGs. The composition and antioxidant activity of the UG extracts were studied in model solutions at different pH levels. The capacity of the UG extracts to protect wine colour was evaluated in accelerated oxidation tests and small-scale trials on both red and white wines during ageing in comparison with sulphur dioxide, ascorbic acid and commercial tannins. The Viognier and Merlot extracts were rich in phenolic acids while the Sangiovese extract was rich in flavonoids. The antioxidant activity of the extracts and commercial tannins was influenced by the pH. In the oxidation tests, the extracts and commercial products showed different wine colour protection capacities in function of the type of wine. During ageing, the white wine with the added Viognier UG extract showed the lowest level of colour oxidation. The colour of the red wine with the UG extract evolved similarly to wine with SO2 and commercial tannins. The obtained results indicated that natural and healthy UG extracts could be an interesting substitute for SO2 during wine ageing.

Understanding the molecular interactions between a yeast protein extract and phenolic compounds

Phenolic compounds are partially removed during fining, which may influence the organoleptic properties of beverages. Among phenolic compounds, tannins have been widely associated to the taste of beverages (namely astringency and bitterness). Furthermore, phenolic acids and anthocyanins may also influence bitterness and the latter are also responsible for beverages' color. Thus, it is necessary to perform molecular studies to better understand the effect of fining agents in the overall phenolic composition of beverages and the resulting organoleptic changes. The molecular interactions between these three classes of phenolic compounds and a yeast protein extract (YPE), designed as a new fining agent, was studied. The binding affinities were assessed by fluorescence quenching at two temperatures (21 °C and 37 °C) and in two reaction media (water and wine model solution). The size of aggregates formed was characterized by Dynamic Light Scattering and the selectivity of protein interaction was analyzed by electrophoresis. Overall, pentagalloylglucoside (tannin) showed the highest binding affinity for YPE, followed by malvidin 3-glucoside (anthocyanin), p-coumaric acid (phenolic acid) and gallic acid (phenolic acid). The studied temperatures and solvents affected the interaction affinities as well as the aggregates' size. Binding selectivity of proteins from YPE was not found. These results open new perspectives to control the fining process by using the YPE as a fining agent taking into account the further effect in the organoleptic properties of beverages.

β-aminobutyric acid induces priming defence against Botrytis cinerea in grapefruit by reducing intercellular redox status that modifies posttranslation of VvNPR1 and its interaction with VvTGA1

Either NPR1 or TGA1 serve as master redox-sensitive transcriptional regulators for the transcription of PR genes in plants. The redox modification of the two co-activators involved in BABA-induced priming resistance against Botrytis cinerea in grapes was examined in this study. The results showed that 10 mmol L^-1 BABA could effectively trigger a priming defense in grapes as manifested by augmented expression levels of PR genes upon inoculation with B. cinerea. Moreover, transcriptome profiling analysis revealed that all of the sets of key genes in the enzymatic ROS scavenging system, the PPP and AsA-GSH cycle were in harmony and were transcriptionally induced in BABA-primed grapes with pathogenic infection; in addition, this enhanced expression caused the accelerated accumulation of reductive substances, namely, AsA, GSH and NADPH, resulting in reduced intercellular conditions. Under reduced conditions, the interaction of VvTGA1 and VvNPR1 in the Y2H assay implied that VvTGA1 can provide the DNA binding capacity required by VvNPR1 for activation of VvPR genes. Consequently, the transactivation of VvNPR1 by the promoters of VvPR1, VvPR2 and VvPR5 was determined via a DLR assay, and it induced the transcription of the VvPR genes. In parallel, the redox-modified reducing condition achieved with an abundant supply of reductive substances was closely associated with the translocation of NPR1 for interaction with TGA in the nucleus. Thus, the posttranslational modification and subsequent interaction of the two redox-sensitive co-activators of VvNPR1 and VvTGA1 under reduced conditions may be responsible for BABA-induced priming for effective disease resistance in grapes.

Extended Harvest Date Alter Flavonoid Composition and Chromatic Characteristics of Plavac Mali (Vitis vinifera L.) Grape Berries

This study delivers a comprehensive flavonoid fingerprint profile, physiochemical and external color characterization of Plavac Mali grapes through four harvest dates at two distinct vineyards (Split and Zadar) in the Eastern Adriatic region. The experimental harvest lasted 56 days, at total soluble solids content from 18.4 to 22.4°Brix in Split and 16.8 to 20.4°Brix in Zadar. Patterns of 27 skin and seed flavonoid compounds at each location indicate unique flavonoid composition of berries at each harvest date. Extended harvest increased six compounds in skin with maximum values of main anthocyanin malvidin-3-O-glucoside in H3 (4406.6 and 6389.5 mg kg⁻¹, Split and Zadar, respectively) followed by a decrease in October. Peak values of seed and skin catechins and galloylated flavan-3-ol subunits are seen in H1 and H2 at Split, while constantly high values are reported in the case of Zadar, with an incoherent pattern of those in skin extracts. Minimal values of epigallocatechin were detected with an extended harvest date at both locations. Berries of extended harvest dates underwent colorimetric improvements, trough decrease in L*, a*, b* and C characteristics and increase in skin color index for red grapes CIRG. The extended harvest date promotes flavonoid composition, and improves the quality of Plavac Mali grape berries.

Winemaking Byproducts as Source of Antioxidant Components: Consumers' Acceptance and Expectations of Phenol-Enriched Plant-Based Food

One of the food industry's priorities is to recover byproducts and move towards more sustainable systems. Among wine-chain byproducts, unripe grapes represent a promising source of antioxidants. However, the development of new foods enriched using phenol-rich ingredients is challenging due to their sensory attributes. The aims of the present study were to (1) use phenol-rich extract from unripe grapes to enrich a model plant-based food (beetroot puree-BP); (2) evaluate consumers' acceptance and expectations for the beetroot purée samples. The effect of information about the sustainability and pro-health activity of value-added ingredients on consumers' responses was also investigated. Four beetroot purees with increasing concentrations of phenol extract (0-1.93 g/kg) added were evaluated by 101 participants in three tasting conditions (blind: only samples; expected: only information without tasting; real: both samples and information).Liking slightly decreased with increasing concentrations of phenol extract, even if all the samples were considered acceptable. The health and sustainability information increased the hedonic expectations, although it was not assimilated by all consumers involved. The development of new phenol-enriched foods using functional ingredients from unripe grapes is challenging. However, it is also promising, since all the samples were generally accepted by the consumers and they presented phenol levels that were stable over time and that could have positive health effects when consumed.

Recovery of Bioactive Compounds from Unripe Red Grapes (cv. Sangiovese) through a Green Extraction

Unripe grapes are a potential source of bioactive compounds which can exert antioxidant and antimicrobial activity. However, very little information is available about the composition of unripe grapes extracts and their extraction techniques. This study aims to evaluate the recovery of bioactive compounds and the antioxidant activity of the extract from unripe Sangiovese grapes obtained at an industrial-scale and the composition of the extract during processing. The extraction yield was approximately 75%. During the extraction, the total phenol (TP), antioxidant activity (AA) total anthocyanin (TAnt), pantothenic acid and choline content significantly increased. High concentrations of TP (2522 mgCATeq/L), AA (8227 μmolTEAC/L) and total water-soluble vitamins (1397 μg/L) were reached at the end of process. The antioxidant activity of the extract was positively correlated with all the phenol compounds and the highest correlations were found with procyanidin B1 (r = 0.994; p-value < 0.004), procyanidin B2 (r = 0.989; p-value < 0.004), kaempferol 3-O-glucoside (r = 0.995; p-value < 0.004) and quercetin 3-O-hexoside (r = 0.995; p-value < 0.071). Our findings contribute to the knowledge of the bioactive composition of unripe grapes. An efficient industrial-scale "green" extraction method, ready to be transferred to the wine sector, was developed to obtain a safe extract with a high concentration of bioactive compounds.