Study on the browning mechanism of betel nut (Betel catechu L.) kernel

Integrated non-targeted metabolomics and transcriptomics reveals the browning mechanism of scraped ginger (Zingiber officinale Rosc.)

Ginger (Zingiber officinale Rosc.) possesses a rich nutritional profile, making it a valuable ingredient for a wide range of culinary applications. After removing its outer skin, ginger can be effectively utilized in the production of pickles and other processed food products. However, following scraping, ginger undergoes a series of physiological and biochemical changes during storage, which can impact its subsequent development and utilization in food. Thus, the current study aimed to investigate the browning mechanism of scraped ginger using non-targeted metabolomics and transcriptomics. The findings revealed 149 shared differential metabolites and 639 shared differential genes among freshly scraped ginger, ginger browned for 5 days, and ginger browned for 15 days. These metabolites and genes are primarily enriched in stilbenes, diarylheptane, and gingerol biosynthesis, phenylpropanoid biosynthesis, and tyrosine metabolism. Through the combined regulation of these pathways, the levels of phenolic components (such as chlorogenic acid and ferulic acid) and the ginger indicator component (6-gingerol) decreased, whereas promoting an increase in the content of coniferaldehyde and curcumin. Additionally, the activities of polyphenol oxidase (PPO) and peroxidase (POD) were significantly increased (p-adjust <0.05). This study hypothesized that chlorogenic and ferulic acid undergo polymerization under the catalysis of PPO and POD, thereby exacerbating the lignification of scraped ginger. These findings offer a theoretical foundation for understanding the browning mechanism of ginger after scraping. PRACTICAL APPLICATION: Ginger's quality and nutrition can change when its skin is removed. This happens due to physical and biochemical reactions during scraping. The browning that occurs affects both the taste and health benefits of ginger, we can better understand how to prevent browning and maintain ginger's quality. This research sheds light on improving ginger processing techniques for better products.

Edible Quality Analysis of Different Areca Nuts: Compositions, Texture Characteristics and Flavor Release Behaviors

The areca nut is one of the most important cash crops in the tropics and has substantial economic value. However, the research information about the edible quality of different areca nuts is still insufficient. This study compared the composition, texture characteristics and flavor release behaviors of four different areca nuts (AN1, AN2, AN3 and AN4) and two commercially dried areca nuts (CAN1 and CAN2). Results showed that AN1 had higher soluble fiber and lower lignin, which was the basis of its lower hardness. Meanwhile, the total soluble solid (TSS) of AN1 was the highest, which indicated that AN1 had a moister and more succulent mouthfeel. After the drying process, the lignification degree of AN1 was the lowest. Through textural analyses, the hardness of AN1 was relatively low compared to the other dried areca nuts. AN1, CAN1 and CAN2 had higher alkaline pectin content and viscosity, and better flavor retention, which indicated better edible quality. The present study revealed the differences of various areca nuts and provided vital information to further advance the study of areca nuts.

Determination of the Content of Phenolic Compounds and the Changes of Polyphenol Oxidase and Each Index during Browning of Phyllanthus emblica at Different Storage Temperatures

In order to further study the early browning of P. emblica marker and mechanism, it is necessary for us to measure the changes in the content of some substances to find quality markers during the browning process of P. emblica. So, we simulated the storage conditions under different temperatures, including 5°C, 25°C, and 35°C. And, the contents of some of its phenolic compounds were determined by RP-HPLC. Polyphenol oxidase (PPO) activity was determined by PPO reagent kits, and pH was determined with a pH measuring instrument, etc. The experimental results showed that 1-galloyl-glucose was the smoothest at 5°C among the three storage temperature conditions. It fluctuates and decreases in a curve at 35°C and 25°C. The content changes of gallic acid (GA) fluctuated more obviously at 35°C, and it showed a maximum value on the 7th day. The content changes of 1,3,6-tri-O-galloyl-β-D-glucose (TGG) all showed a peak on the 5th day and then showed a gradual decrease. The content changes of ellagic acid (EA) fluctuated more at 35°C. The peak of the content of rutin at both 35°C and 25°C appeared on the 3rd day, and that showed a gradually decreasing trend. The PPO activity varied more significantly at 25°C and 35°C. The browning index increased with time at both 35°C and 25°C. The complete browning of P. emblica was already observed on the 13th day. Tips for experimental results 5°C are effective in preventing browning of P. emblica. The contents of TGG, 1-galloyl-glucose, and rutin in P. emblica are greatly affected by temperature and time, and its contents had a linear relationship with time and temperature and can be used as one of the indicators of early browning, which provides a reference for the storage and transportation of fresh fruit in Chinese herbals.

Enzymatic browning in relation to permeation of oxygen into the kernel of postharvest areca nut under different storage temperatures

Previous study indicates that kernel of areca nut is susceptible to enzymatic browning caused by phenolic oxidation, which involves the ingression of oxygen into interior tissue. However, the reason for permeation of oxygen into the interior of areca nut and its possible influencing factors (e.g., temperatures) are little known. In the present study, we set three storage temperatures (25, 10, and 5°C) and investigated the effects on kernel browning and related physic-biochemical and tissue morphological changes. The results showed that the most severe kernel browning was observed in areca nut stored at 25°C, followed by 5°C. Comparatively, a slower browning development was found in areca nut stored at 10°C. More serious kernel browning at 25 and 5°C might be attributed to increased membrane permeability and aggravated tissue damage in view of morphological observations on pericarp, mesocarp, and kernel shell. Higher lignin content and phenylalanine ammonia-lyase activity were observed in mesocarp of areca nuts stored at 25 and 5°C as compared to 10°C, indicating that mesocarp lignification could facilitate the permeability of oxygen. Furthermore, the data showed that storage at 25 and 5°C induced the higher polyphenol oxidase activity while accelerating the decline in total phenolic content in areca nut kernel, which could contribute to higher occurrence of enzymatic browning reaction compared to that at 10°C. These results suggest that natural senescence at 25°C and severe chilling stress at 5°C could be influencing factors triggering the permeation of oxygen, leading to internal kernel browning in areca nut.