Phytic Acid Treatment Inhibits Browning and Lignification to Promote the Quality of Fresh-Cut Apples during Storage

Phytic Acid Delays the Senescence of Rosa roxburghii Fruit by Regulating Antioxidant Capacity and the Ascorbate-Glutathione Cycle

Rosa roxburghii fruit has a short postharvest shelf life, with rapid declines in quality and antioxidant capacity. This research assessed how phytic acid affects the antioxidant capacity and quality of R. roxburghii fruit while in the postharvest storage period and reveals its potential mechanism of action. The findings suggested that phytic acid treatment inhibits the production of malondialdehyde (MDA) and enhances the activities and expressions of glutathione peroxidase (GPX), peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) while decreasing the generation of superoxide anions (O2•-) and hydrogen peroxide (H2O2). Phytic acid treatment activates the ascorbate-glutathione (AsA-GSH) cycle and enhances the activity and expression of key enzymes in the cycle: ascorbate peroxidase (APX), glutathione reductase (GR), dehydroascorbate reductase (DHAR), and monodehydroascorbate reductase (MDHAR). It also increases the levels of non-enzymatic antioxidants, such as ascorbic acid (AsA) and glutathione (GSH), while reducing the production of dehydroascorbic acid (DHA) and oxidized glutathione (GSSG). Moreover, phytic acid treatment enhances the ratios of AsA/DHA and GSH/GSSG, maintaining the reduced state of the fruit. In summary, phytic acid improves antioxidant defense system and activates the AsA-GSH cycle, alleviating oxidative damage and ensuring R. roxburghii fruit quality after harvest.

The occurrence, role, and management strategies for phytic acid in foods

Phytic acid, a naturally occurring compound predominantly found in cereals and legumes, is the focus of this review. This review investigates its distribution across various food sources, elucidating its dual roles in foods. It also provides new insights into the change in phytic acid level during food storage and the evolving trends in phytic acid management. Although phytic acid can function as a potent color stabilizer, flavor enhancer, and preservative, its antinutritional effects in foods restrict its applications. In terms of management strategies, numerous treatments for degrading phytic acid have been reported, each with varying degradation efficacies and distinct mechanisms of action. These treatments encompass traditional methods, biological approaches, and emerging technologies. Traditional processing techniques such as soaking, milling, dehulling, heating, and germination appear to effectively reduce phytic acid levels in processed foods. Additionally, fermentation and phytase hydrolysis demonstrated significant potential for managing phytic acid in food processing. In the future, genetic modification, due to its high efficiency and minimal environmental impact, should be prioritized to downregulate the biosynthesis of phytic acid. The review also delves into the biosynthesis and metabolism of phytic acid and elaborates on the mitigation mechanism of phytic acid using biotechnology. The challenges in the application of phytic acid in the food industry were also discussed. This study contributes to a better understanding of the roles phytic acid plays in food and the sustainability and safety of the food industry.

Inhibitory effect and molecular mechanism on tyrosinase and browning of fresh-cut apple by longan shell tannins

Tyrosinase is a biological macromolecule closely related to browning of fruit and vegetables, melanin production, and tyrosinase inhibitors are usually used to prevent browning and pigmentation. In this study, longan shell tannins (LSTs) were screened as tyrosinase inhibitors and their structures were proved to be mixtures of procyanidins (condensed tannins) and ellagitannins (hydrolyzed tannins). Enzymatic experiments verified that LSTs were efficient inhibitors, and the IC50 values for monophenolase and bisphenolase were 176.04 ± 10 and 59.94 ± 5 μg mL-1, respectively. Fluorescence detections and molecular docking revealed that the combination of LSTs to tyrosinase was mainly driven by hydrogen bonding, hydrophobic interaction, as well as van der Waals force, which changed the microenvironment of tyrosine and tryptophan residues as well as enzyme conformation. Circular dichroism and molecular dynamics simulation showed that LSTs affected secondary structures of tyrosinase, resulting in structural stretching and conformational modification of the enzyme. In addition, preservation studies demonstrated that LSTs owned the ability to delay the browning of fresh-cut apples by inhibiting phenolic metabolism, strengthening the antioxidant system, and reducing lipid peroxidation. This paper testified that LSTs are exteaordinary tyrosinase inhibitors, and offered a scientific foundation for the application of LSTs in food industry and medicine.

Quality maintenance mechanism of oxalic acid treatment in fresh-cut apple fruit during storage based on nontarget metabolomics analysis

A complicated storage reaction mechanism will occur during the storage period in fresh-cut apples, and oxalic acid could physiologically modify the flesh tissue to achieve preservation purposes. This study revealed the storage quality regulation mechanism treated with oxalic acid (3 mmol⋅L-1) in fresh-cut apples through nontarget metabolomics and physiological analyses. It was discovered that oxalic acid could enhance the antioxidant enzymes activities, i.e. superoxide dismutase, catalase, glutathione reductase, etc., contents of soluble solids, total phenolic and reducing sugar, postpone the enhancement of hydrogen peroxide and superoxide anion, and defer the decrease of titratable acid, hardness and total antioxidant capacity. 427 differentially expressed metabolites were identified by nontarget metabolomics. Among them, mainly involved in glycerol ester metabolism, phenylalanine metabolism, starch and sucrose metabolism, etc. were up-regulated treated with oxalic acid. In summary, oxalic acid could enhance the antioxidant properties and regulate metabolite synthesis, leading to delayed quality deterioration of fresh-cut apples.

Ectopic expression of SaCTP3 from the hyperaccumulator Sedum alfredii in sorghum increases Cd accumulation for phytoextraction

The Cd tolerance protein SaCTP3, which responds to Cd stress, was identified in Sedum alfredii; however, how to improve the efficiency of phytoremediation of Cd-contaminated soil using the CTP gene remains unknown. In this study, the phytoremediation potential of SaCTP3 of Sedum alfredii was identified. In the yeast Cd-sensitive strain Δycf1 overexpressing SaCTP3, the accumulation of Cd was higher than that in the Δycf1 strain overexpressing an empty vector. Transgenic sorghum plants overexpression SaCTP3 were further constructed to verify the function of SaCTP3. Compared to wild-type plants, the SaCTP3-overexpressing lines exhibited higher Cd accumulation under 500 μM Cd conditions. The average Cd content inSaCTP3-overexpressing plants is more than four times higher than that of WT plants. This was accompanied by an enhanced ability to scavenge ROS, as evidenced by the significantly increased activities of peroxidase, catalase, and superoxide dismutase in response to Cd stress. Pot experiments further demonstrated that SaCTP3 overexpression resulted in improved soil Cd scavenging and photosynthetic abilities. After 20 days of growth, the average Cd content in the soil planted with SaCTP3-overexpressing sorghum decreased by 19.4%, while the residual Cd content in the soil planted with wild-type plants was only reduced by 5.4%. This study elucidated the role of SaCTP3 from S.alfredii, highlighting its potential utility in genetically modifying sorghum for the effective phytoremediation of Cd.

Antioxidant effects of phenolic extract from sugarcane straw and mannan extract from brewer's spent yeast on fresh-cut apples

BACKGROUND

Fresh-cut fruit are convenient ready-to-eat products increasingly demanded by consumers, but highly susceptible to oxidation. To increase the shelf life of these products, this industry is currently facing the challenge of finding sustainable natural preservatives capable of maintaining fresh-cut fruit quality while meeting consumers' expectations regarding health and environmental concerns.

RESULTS

In this work, fresh-cut apple slices were treated with two antioxidant extracts derived from industrial by-products: a phenolic-rich extract produced from sugarcane straw (PE-SCS) and applied at 15 g L-1 , and a mannan-rich extract obtained from brewer's spent yeast (MN-BSY) applied at two concentrations: 1 and 5 g L-1 . PE-SCS, having a brown color, imparted a brownish hue to the fruit and increased the browning rate during storage, and not even the initial robust antioxidant response (high superoxide dismutase, catalase, ascorbate peroxidase and guaiacol peroxidase activities), prevented oxidation. Fruit treated with MN-BSY extract at 5 g L-1 showed lower color loss rate and higher polyphenol oxidase inhibition, while at 1 g L-1 it showed lower firmness loss rate and lower lipid peroxidation after 6 days of storage.

CONCLUSION

The results showed that PE-SCS triggers a potent antioxidant response in fresh-cut fruit and, despite it imparting a brown color to the fruit at 15 g L-1 , it may have potential for application at lower concentrations. Regarding MN-BSY, it generally decreased oxidative stress, but its effect on quality maintenance was dependent on the concentration and, thus, to confirm its potential as a fruit preservative more concentrations must be tested. © 2023 Society of Chemical Industry.

A new strategy for browning regulation: Flos Sophorae Immaturus extract and thermal treatment modulates nitric oxide and reactive oxygen species network in fresh-cut potatoes

Browning discoloration is a critical issue that negatively affects the quality of fresh-cut products and their industrial growth. Although many individual anti-browning technologies have been adopted, very few reports on the combination use of natural product extracts and physical methods exist. This study investigated the use of Flos Sophorae Immaturus extract in conjunction with thermal treatment and discovered that the combination effectively retarded browning in fresh-cut potatoes. Accordingly, the activities of polyphenol oxidase, peroxidase, and phenylalanine ammonia-lyase, as well as phenol accumulation, were effectively regulated. Meanwhile, this combination treatment also allowed for the modulation of nitric oxide synthase, superoxide dismutase, and catalase activities, while also regulating the concentrations of nitric oxide, superoxide anion, and hydrogen peroxide. Furthermore, the duplex treatment also regulated the antioxidant capacity and malondialdehyde concentrations. In addition, 39 phytoactive compounds, including protocatechuic acid, quercetin, (-)-alpha-pinene, and matrine, were identified in the extract, which may function as the anti-browning composition. These findings suggest that the combination technology modulated the dynamic equilibrium of production and clearance of nitric oxide and reactive oxygen species, thereby reducing browning deterioration. This is, to our knowledge, the first report of the combined application of Flos Sophorae Immaturus and thermal treatment, which may offer a novel option for fresh-cut preservation. PRACTICAL APPLICATION: The feasibility of integrating a novel highly efficient, safe, environmentally friendly, and easy-to-operate anti-browning alternative, with the ability to integrate into the existing processing line was investigated. The color of sliced potato chips was significantly improved (73.4%) by dipping them in a 0.01% Flos Sophorae Immaturus solution for 5 min and then in 55°C water for 2 min. In this regard, superior browning alleviation may depend on the regulation of the browning reaction and the NO-ROS network. This method has a promising future for making fresh-cut products more appealing to consumers and may provide guidance for fresh-cut producers and related industries.

Inhibitive effects of phytic acid combined with glutathione on the browning and oxidation of King Oyster mushroom (Pleurotus eryngii) slices during drying and storage

Phytic acid and glutathione can inhibit polyphenoloxidase (PPO) activity and suppress browning. This study investigated the effects of phytic acid alone (Treatment-1) or combined with glutathione (Treatment-2) on inhibiting browning and oxidation resistance of King Oyster mushroom (Pleurotus eryngii) slices during drying and storage. In King Oyster mushroom slices, 0.08% phytic acid combined with 0.1% glutathione inhibited the PPO activity by 97.6%, suppressed browning by 78.09% after 6 h of drying at 60 °C and inhibited browning by 69.93% and oxidation by 78.75% after 12 months of storage at ∼ 20 °C. Results indicated that using phytic acid combined with glutathione may inhibit browning and suppress the oxidation of King Oyster mushroom slices during drying and storage.