Effect of thermal shock cycling on storage stability and quality of fresh-cut potato

Untargeted Metabolomics Using UHPLC-HRMS Reveals Metabolic Changes of Fresh-Cut Potato during Browning Process

Surface browning plays a major role in the quality loss of fresh-cut potatoes. Untargeted metabolomics were used to understand the metabolic changes of fresh-cut potato during the browning process. Their metabolites were profiled by ultra-high performance liquid chromatography coupled with high resolution mass spectrometry (UHPLC-HRMS). Data processing and metabolite annotation were completed by Compound Discoverer 3.3 software. Statistical analysis was applied to screen the key metabolites correlating with browning process. Fifteen key metabolites responsible for the browning process were putatively identified. Moreover, after analysis of the metabolic causes of glutamic acid, linolenic acid, glutathione, adenine, 12-OPDA and AMP, we found that the browning process of fresh-cut potatoes was related to the structural dissociation of the membrane, oxidation and reduction reaction and energy shortage. This work provides a reference for further investigation into the mechanism of browning in fresh-cut products.

The Effect of Sodium Nitroprusside Treatment on Storage Ability of Fresh-Cut Potato

Quality deterioration is a major problem restricting the fresh-cut potato industry. The present study investigated the effect of sodium nitroprusside (SNP) treatment on the quality of fresh-cut potatoes during short-term storage. The treatment was carried out immediately either before or after cutting, using an SNP concentration of 200 μmol/L. The results showed that SNP treatment inhibited the accumulation of malondialdehyde (MDA) and total soluble solids (TSSs). SNP treatment also decreased the firmness, chewing properties, and ascorbic acid (AsA) content in potatoes, maintaining high levels of total phenols (TPs), total flavonoids (TFs), nitric oxide (NO), and superoxide dismutase (SOD). Furthermore, SNP treatment restrained the rise of phenylalanine ammonia-lyase (PAL), peroxidase (POD), and polyphenol oxidase (PPO), as well as the electrolyte leakage (EL) rate. After SNP treatment, the nitrite content in the potatoes was within security scope. Comparing potatoes treated before and after cutting, the best result was noted in the potatoes soaked in SNP before cutting, which displayed the smallest losses in firmness (11.24%), chewing properties (34.30%), and AsA (40.35%), and maximum increases in TPs (32.84%), TFs (2.83-time), NO (76.11%), and SOD activity (93.15%). Moreover, this group presented the minimum MDA content, EL rate, and TSS values and the lowest PAL, POD, and PPO activities. These results indicated that 200 μmol/L SNP applied for 20 min, particularly before cutting, is an efficient alternative technology that can be used in the fresh-cut potato industry.

Evaluation of cooking, nutritional, and quality characteristics of fresh-cut potato slice pretreated with acetic acid

Fresh-cut potato slices are very popular in the service of hot-pots. However, the gelatinized starch easily escaping from the potato cells during cooking causes the thickening of beef tallow or soup in the hot-pot. Thus, acetic acid is considered for solving the problem of potato slices. Besides, the nutritional and quality characteristics of potato slices are also evaluated in this study. Results show that 1.0%-1.5% (v/v) acetic acid treatment can decrease mass loss and starch digestion rate, and delay the degradation of ascorbic acid and deterioration of color and texture of potato slices. Such treatment also inhibits membrane oxidation and PPO activity, and increase the total phenolic accumulation of potato slice in 7-day storage. The cell wall integrity of the potato slice is strengthened by acetic acid treatment, providing a strategy for the improvement of the boiling resistance of potato slice, and endowing potato slice with the digesting resistance. PRACTICAL APPLICATION: Acid pretreatment would cause the intensification of potato cell wall, which finally decrease the in vitro digestibility through decrease of leakage of gelatinized starch from potato cell and the contact between gelatinized starch and digesting enzyme. This observation proved that the integrity of cell structure in vegetable is important for their processing quality improvement (especially for their hardness improvement after heating or fermentation).

Intensive pulsed light pretreatment combined with controlled temperature and humidity for convection drying to reduce browning and improve quality of dried shiitake mushrooms

BACKGROUND

The change of surface color caused by browning during the drying process of shiitake mushrooms seriously affects its market circulation. Intensive pulsed light (IPL) as a non-heat-treatment method can reduce enzyme activity by changing the enzyme structure. Therefore, in this study, the use of IPL pretreatment before drying was aimed to reduce the adverse reactions caused by the browning reaction during the drying processing of shiitake mushrooms.

RESULTS

Shiitake mushrooms pretreated with 25 pulses of IPL energy of 400 J reduced the initial polyphenol oxidase enzyme activity, the browning index, and browning degree values by 42.83%, 43.02%, and 47.54% respectively. The IPL pretreatment enhanced the polysaccharides and reducing sugars contents and it reduced 5-hydroxymethylfurfural generation in the dried shiitake mushrooms. The pretreatment also improved the surface color, the antioxidant activity, and retained the umami taste characteristics in the dried shiitake mushroom.

CONCLUSION

The IPL pretreatment combined with controlled temperature and humidity for convection drying could be a suitable method to improve the quality of dried shiitake mushrooms. Therefore, this study provides a new pretreatment method for materials that are prone to browning during drying. © 2021 Society of Chemical Industry.

Novel alternative for controlling enzymatic browning: Catalase and its application in fresh-cut potatoes

Surface browning is a vital phenomenon that adversely reduces the quality of fresh-cut potatoes. Although many anti-browning methods have been explored, it is unclear whether exogenous catalase (CAT) treatment influences the enzymatic browning. Our results showed that 0.05% CAT immersion for 5 min alleviated browning during cold storage (4°C, 8 days), which was accompanied by a higher lightness and lower redness; additionally, lower H₂ O₂ and O₂ ·- contents were found. The activities of CAT, ascorbate peroxidase, and glutathione peroxidase and the scavenging efficiency of 2,2-diphenyl-1-picrylhydrazyl were also increased. Moreover, CAT treatment inhibited the activities of polyphenol oxidase, peroxidase, and phenylalanine ammonia lyase and reduced phenol accumulation. Treatment with 0.1% hydrogen peroxide (H₂ O₂ ) achieved the opposite results. This is the first report of CAT application reducing fresh-cut potato browning, providing a safe treatment alternative for enzymatic discoloration and preliminarily revealing the underlying mechanism with insight into antioxidant regulation. PRACTICAL APPLICATION: This research is helpful for fresh-cut potato producers because a novel, safe, easy-to-carry out anti-browning solution was proposed. Dipping in 0.05% catalase solution for 5 min revealed color improvement in the quality of fresh-cut potato slices. The mechanism may rely on enhancing antioxidant ability (ascorbate peroxidase, and glutathione peroxidase, and 2,2-diphenyl-1-picrylhydrazyl scavenging), reducing reactive oxygen species (H₂ O₂ , O₂ ·-, malondialdehyde) and controlling enzymatic browning reaction factors (polyphenol oxidase, peroxidase, and phenylalanine ammonia lyase, and phenol accumulation). This method shows promise for better meeting the requirements and demands of consumers for fresh quality products.