Delaying the biosynthesis of aromatic secondary metabolites in postharvest strawberry fruit exposed to elevated CO2 atmosphere

The regulation of postharvest strawberry quality mediated by abscisic acid under elevated CO2 stress

Elevated CO2 was a potential strategy for strawberry preservation. However, the regulatory mechanism remained unclear. In current study, transcriptome analysis showed that elevated CO2 played important roles in regulating strawberry fruit quality at the transcriptional level, and plant hormones metabolism at least partially involved in the regulatory process. Further, ABA was demonstrated to play important roles in the response to elevated CO2. Elevated CO2 inhibited the accumulation of ABA, which was 61% lower than that in control. Elevated CO2 repressed ABA synthesis by inhibiting NCED activity and the expression of FaNCED1/2, leading to the reduction of ABA accumulation as a result. Meanwhile, elevated CO2 also decreased ABA sensitivity by down-regulating FaSnRK2.4/2.6 and FaABI5 expression. The dual down-regulation of ABA signaling accounted for the regulation of fruit quality under elevated CO2 treatment. These results provide new insights into the mechanism of strawberry fruit response to elevated CO2.

Regulation of anthocyanin synthesis in red lettuce in plant factory conditions: A review

Anthocyanins, natural pigments known for their vibrant hues and beneficial properties, undergo intricate genetic control. However, red vegetables grown in plant factories frequently exhibit reduced anthocyanin synthesis compared to those in open fields due to factors like inadequate light, temperature, humidity, and nutrient availability. Comprehending these factors is essential for optimizing plant factory environments to enhance anthocyanin synthesis. This review insights the impact of physiological and genetic factors on the production of anthocyanins in red lettuce grown under controlled conditions. Further, we aim to gain a better understanding of the mechanisms involved in both synthesis and degradation of anthocyanins. Moreover, this review summarizes the identified regulators of anthocyanin synthesis in lettuce, addressing the gap in knowledge on controlling anthocyanin production in plant factories, with potential implications for various crops beyond red lettuce.

Composition of free sugars and organic acids in Japanese strawberry cultivars and their influence on the perception of sweetness and sourness

This study aimed to determine the extent of variations in the ratio of major free sugars to total sugars and major organic acids to total organic acids in strawberry juice with cultivar and harvest season and investigate whether these differences affect the perceived intensity of sweetness and sourness. Eight Japanese strawberry cultivars were simultaneously grown and harvested in different seasons for sugar and organic acid content analyses. In addition, simulated strawberry juices, containing equal total amounts of sugars and organic acids but in different ratios, were prepared based on their analytical values. The perceived intensities of sweetness and sourness of the juices were subjected to sensory evaluation. The results showed a wide range of sucrose compositions, ranging from almost zero to the highest ratio of 36.7% to total sugar. Glucose and fructose were present in approximately equal amounts, with a slight inclination toward more fructose. For organic acids, the highest ratio of citric acid was 87.6%, the lowest was approximately 60.1%, and the remainder comprised malic acid. The results of the sensory evaluation using simulated strawberry juice indicated that sweetness and sourness were significantly more pronounced as the ratio of sucrose to total sugar and the ratio of malic acid to total organic acid increased, respectively. These results suggest that it is essential to consider not only total soluble solids and titratable acidity but also the composition of the sugars and organic acids comprising them when evaluating strawberry taste. PRACTICAL APPLICATION: Total soluble solids and titratable acidity have been used to evaluate strawberry taste; however, how the composition and ratios of the sugars and organic acids that comprise them affect the taste is unclear. This study revealed that, for sugars, an increase in the proportion of sucrose resulted in a stronger perception of sweetness, and for organic acids, an increase in the proportion of malic acid resulted in a stronger perception of sourness. These findings are expected to be useful in future studies evaluating strawberry taste and palatability.

Controlled Atmosphere Improves the Quality, Antioxidant Activity and Phenolic Content of Yellow Peach during the Shelf Life

Controlled atmosphere (CA) has been demonstrated to maintain the shelf-life quality of fruits, but its effect on the antioxidant activities and phenolic content of yellow peach is not comprehensive. This study analyzed the role of CA on the quality of shelf period, phenolic content and antioxidant activity of "Jinxiu" yellow peach. Yellow peach was left under specific aeration conditions (3.5-4% CO2, 2-3% O2, 92-95.5% N2, 1 ± 0.5 °C) and the control (1 ± 0.5 °C) for 21 d, to observe changes in physiological parameters of the fruit during 10 d of the shelf life (25 ± 1 °C). The result showed that CA reduced the weight loss rate (WLR), decay rate (DR), and browning index (BI) of yellow peaches. Furthermore, the CA held a high level of total flavonoid content (TFC), total phenol content (TPC) and phenolic content in the fruit. Antioxidant analysis showed that polyphenol oxidase (PPO) enzyme activity was lower and free radical scavenging capacity (DPPH, ABTS, and FRAP) and antioxidant enzyme activities (POD and PAL) were higher in the CA group. Combining the results of significance analysis, correlation analysis, principal component analysis (PCA) and hierarchical cluster analysis (HCA) clearly identified the differences between the CA group and the control group. The results showed that the CA could maintain higher phenolic content and reduce the oxidation of yellow peach fruit and enhance fruit quality by affecting the antioxidant activities of yellow peach.

Effect of glycinebetaine on metabolite profiles of cold-stored strawberry revealed by 1H NMR-based metabolomics

Glycinebetaine (GB) has long been used as a preservative for refrigerated fruits, but the effect of GB on the global metabolites of cold-stored strawberries is still unclear. In this study, the effects of exogenous application of GB on quality-related metabolites of cold-stored strawberries were investigated by nuclear magnetic resonance (NMR)-based metabolomic analysis. The results showed that the application of GB (especially at the concentration of 10 mM) on cold-stored strawberries effectively stabilized the sugars (d-xylose and d-glucose) and amino acids (tyrosine, leucine, and tryptophan) content, and lowered the acid (acetic acid) content as well. Additionally, the GB content in strawberries also increased. This implies that the appropriate concentration of GB is a natural and safe treatment, which could maintain the quality of cold-stored strawberries by regulating levels of quality-related metabolites, and the ingestion of GB-preserved strawberries may serve as a source of methyl-donor supplementation in our daily diet.

Enzymes and microorganisms jointly promote the fermentation of rapeseed cake

Rapeseed cake is a by-product of rapeseed oil separation. The nutritional components of rapeseed cake mainly include a variety of carbohydrates, proteins, and minerals. In order to improve the conversion rate of rapeseed cake, we studied the physicochemical properties, the structure of microbial communities, and the composition of metabolites in rapeseed cake after enzymatic fermentation. The results showed that the addition of enzymatic preparation increased microbial diversity. The relative abundance of Bacillus, Lysinibacillus, Empedobacter, Debaryomyces, Hyphopichia, and Komagataella in enzymatic fermentation was significantly higher than that in natural fermentation. Unlike natural fermentation, microbial diversity during enzymatic fermentation is specific, which improves the efficiency of fermentation. Otherwise, enzymatic fermentation promotes the conversion of macromolecular substances in rapeseed cake, which increases small metabolites, such as fatty acids, organic acids, amino acids and their derivatives. The metabolite enrichment pathway is mostly concentrated in sugar metabolism and fatty acid metabolism. In conclusion, after adding enzymatic preparation, enzymes and microorganisms jointly promote the transformation of macromolecules during the fermentation of rapeseed cake, which laid a good foundation for further utilization of rapeseed cake.

Beneficial Effects of Sodium Nitroprusside on the Aroma, Flavors, and Anthocyanin Accumulation in Blood Orange Fruits

The quality of Tarocco blood orange (Citrus sinensis (L.) Osbeck), which has been cultivated for many years, has degraded substantially. Decreased sugar content, decreased blood color, and increased sour flavor have developed as a result. To improve fruit quality, we studied the effects of bagging and sodium nitroprusside, as a nitric oxide (NO) donor, on the fruit quality of Tarocco blood orange two months before picking. The results showed that NO treatment effectively improved the content of total soluble solids and limonene in the fruit, as well as the color and hardness of the fruit, but reduced the tannin content. It also increased the contents of soluble sugar, fructose, sucrose, vitamin C, amino acids, and mineral elements. NO treatment inhibited the activities of polygalacturonase and pectin esterase, delayed the degradation of protopectin, and promoted the accumulation of anthocyanins, total flavonoids, and flavonoids synthesis. Thus, NO treatment improved the aroma, flavors, and physical properties of blood orange fruit.

Evaluation of the Antioxidant Activity, Deodorizing Effect, and Antibacterial Activity of 'Porotan' Chestnut By-Products and Establishment of a Compound Paper

Chestnuts are widely cultivated for their edible portion (kernel), whereas the non-edible parts are discarded. To enable the utilization of the by-products of processed chestnuts, we separated them into green and brown burs, shells, inner skin, and leaves, and analyzed the bioactive properties of the ground components. We also created a composite paper, comprising the inner skin, and examined its deodorant properties. It was revealed that the inner skin had the highest functionality and showed potent antioxidant, antibacterial, and deodorant properties. Furthermore, when we produced a paper, containing 60% inner skin, and examined its deodorant properties, we found that it was highly effective in deodorizing ammonia and acetic acid gases. These results show that the inner skin of chestnuts is a promising material for developing hygiene and other products.

A novel phase change coolant promoted quality attributes and glutamate accumulation in postharvest shiitake mushrooms involved in energy metabolism

Cold chain transportation is an important link in postharvest logistics of agricultural products. In current study, we developed a novel water-based phase change coolant (PCC), which showed longer effectiveness in maintaining low temperature condition compared with ice, and applied in preserving the postharvest mushrooms. The results showed that the novel PCC effectively inhibited water loss, as well as maintained quality attributes including firmness, color, phenolics, flavonoids, and thus prolonged the shelf-life of mushrooms. Low temperature condition created by the novel PCC treatment maintained high level of energy charge by activating the activities of SDH, CCO, H⁺-ATPase and Ca²⁺-ATPase, resulting in the delay of postharvest senescence. In addition, sufficient energy supply decreased the consumption of glutamate as carbon skeleton by inhibiting GDH activity, improved glutamate accumulation, and therefore maintained sensory properties as a result. Thus, the novel PCC might be an excellent substitute for ice in cold chain transportation of mushrooms.

Nutritional component changes in Xiangfen 1 banana at different developmental stages

Banana is an essential food resource in many tropical and subtropical countries. Metabolites in banana greatly influence its nutritional value and flavor. However, metabolic changes that occur in different developmental stages have not been comprehensively evaluated. In this study, widely targeted metabolomics based on multiple reaction monitoring was used in investigating dynamic changes in metabolites at three stages of fruit development. A total of 655 metabolites were identified in all the stages. A hierarchical cluster analysis of metabolites showed six clear expression patterns at the three developmental stages, and 69 up-regulated differential metabolites were identified in mature fruits compared with young and mature green fruits. A metabolic pathway analysis of differential metabolites showed significant enrichment of the flavonoid biosynthesis pathway and the phenylalanine, tyrosine, and tryptophan biosynthesis pathways. These results may serve as a reference for the isolation and identification of functional compounds from banana and for their sufficient utilization in the future.

High Carbon Dioxide Treatment Modulates Sugar Metabolism and Maintains the Quality of Fresh-Cut Pear Fruit

The purpose of this study is to explore the effect of 10% carbon dioxide (CO₂) on the fruit quality and sugar metabolism of fresh-cut pear during storage. The results indicated that carbon dioxide treatment maintained fruit quality by delaying the decline of firmness and promoting the accumulation of total soluble solids (TSS). Moreover, carbon dioxide enhanced activities of sucrose synthase (SS), and sucrose phosphate synthase (SPS). The activities of amylase, acid invertase (AI), neutral invertase (NI), SS-cleavage, fructokinase (FK), hexokinase (HK), sorbitol oxidase (SOX), NAD-dependent sorbitol dehydrogenase (NAD-SDH), and NADP-SDH in CO₂-treated fruit were inhibited. Expression levels of key genes were found to correspond with the related enzyme activities. As a result, the accumulation of glucose, fructose, sorbitol, and sucrose were accelerated by CO₂, which were 12.58%, 13.86%, 24.7%, and 13.9% higher than those of the control at the end of storage, respectively. The results showed that CO₂ could maintain the quality of fresh-cut pears by regulating the conversion of various sugar components to enhance soluble sugars content.

Effect of Trichoderma Bioactive Metabolite Treatments on the Production, Quality, and Protein Profile of Strawberry Fruits

Fungi of the genus Trichoderma produce secondary metabolites having several biological activities that affect plant metabolism. We examined the effect of three Trichoderma bioactive metabolites (BAMs), namely, 6-pentyl-α-pyrone (6PP), harzianic acid (HA), and hydrophobin 1 (HYTLO1), on yield, fruit quality, and protein representation of strawberry plants. In particular, 6PP and HA increased the plant yield and number of fruits, when compared to control, while HYTLO1 promoted the growth of the roots and increased the total soluble solids content up to 19% and the accumulation of ascorbic acid and cyanidin 3-O-glucoside in red ripened fruits. Proteomic analysis showed that BAMs influenced the representation of proteins associated with the protein metabolism, response to stress/external stimuli, vesicle trafficking, carbon/energy, and secondary metabolism. Results suggest that the application of Trichoderma BAMs affects strawberry plant productivity and fruit quality and integrate previous observations on deregulated molecular processes in roots and leaves of Trichoderma-treated plants with original data on fruits.