Impact of post-harvest storage conditions on polyphenol composition and antioxidant activity in natural almonds
Background: Post-harvest storage of natural almonds is a critical step, as it can cause the onset of microbial contamination and modify polyphenolic composition of almond skin, potentially altering the antioxidant capacity and overall, the health effects of the native product. This study aims to evaluate the impact of different post-harvest storage conditions on the microbiological stability, polyphenolic profile, and antioxidant activity of natural almonds (Prunus dulcis cv. "Fascionello"). Methods: Natural almonds were obtained from Consorzio Mandorla di Avola and stored under three conditions: light exposure at room temperature (RT), dark at RT, and dark at 4°C, monitoring temperature and relative humidity. Samples were analyzed at four time points (T0, T3, T6, and T9 months). Microbiological stability was assessed using standard plate-counting techniques; polyphenolic content was determined through spectrophotometric assays and RP-LC-DAD-ESI-MS/MS analysis, whereas the antioxidant activity was evaluated using different spectrophotometric and spectrofluorimetric assays including DPPH, TEAC, FRAP, and ORAC assays. Chemometric analyses were performed to compare polyphenolic changes across different storage conditions over time. Results: Temperature remained stable with moderate variations, indicating a well-controlled environment, while humidity exhibits significant fluctuations, likely influenced by external factors. No significant microbial contamination was detected throughout storage, confirming the microbiological safety of natural almonds. The polyphenolic content significantly decreased within the first 3 months, particularly under dark conditions at RT. However, a recovery phase was observed at 6 months, with cold-stored almonds retaining the highest levels of total polyphenols and flavonoids. The antioxidant activity of almond skin extracts correlated with polyphenolic content, showing an initial decline followed by stabilization under refrigerated storage. Hierarchical clustering analyses highlighted distinct polyphenolic expression patterns based on storage conditions and time points. Conclusion: Post-harvest storage conditions significantly impact the polyphenolic profile and antioxidant properties of natural almonds. For short-term storage (≤6 months), RT with controlled light exposure is sufficient to preserve polyphenols, whereas cold and dark conditions are recommended to maintain bioactive compound stability and antioxidant potential for long-term storage (>6 months). These findings provide valuable insights for optimizing storage strategies in the food, nutraceutical, and pharmaceutical industries.
https://doi.org/10.3389/fnut.2025.1582434
Investigating the influence of pin-to-plate atmospheric cold plasma on the physiochemical, nutritional, and shelf-life study of two raisins varieties during storage
Cold plasma technology, a non-thermal food processing method, significantly enhances food quality and safety by modifying its physicochemical and nutritional attributes. Additionally, this treatment extends the shelf-life of food products, ensuring prolonged freshness and improved overall quality. The present study systematically examined the effect of cold plasma treatment on various attributes, including moisture content (MC), pH, hardness (H), antioxidant activity (AOA), total phenolic content (TPC), rehydration ratio (Rr), browning index (BI), and color difference (ΔE) in black raisins (BR) and golden raisins (GR). The comprehensive analysis delivers valuable insights into the transformative influences of cold plasma on the physicochemical and nutritional characteristics of these raisin varieties. A Box–Behnken experimental design (BBD) combined with response surface methodology (RSM) was used to determine the optimization of treatment time (5, 10 and 15 min) and voltage (10, 20 and 30 kV). The optimized time and voltage for black raisins was 10 kV with 15 min, whereas, for golden raisins, it was 20 kV with 10 min. Furthermore, the experimentation of shelf-life studies for both raisins illuminated the substantial impact of cold plasma treatment, notably enhancing H, Rr, BI, AOA and TPC. Concurrently, a decline in MC and pH was observed throughout the storage period. Furthermore, plasma treatment improved the quality of raisins by reducing the total mesophilic aerobic bacteria count as compared to untreated ones from 4.65–2.42 to 4.71–2.40 log CFU/g for BR and GR, respectively, and similar results were also noticed in mold and yeast count during the 15 days of storage period. However, Future research of this study should delve into long-term storage effects, scalability for commercial applications, and the underlying mechanisms driving these improvements in raisin quality.
https://doi.org/10.1007/s11694-024-02764-8
Performance of two egg parasitoids of brown marmorated stink bug before and after cold storage
Introduction: The genus Trissolcus includes a number of egg parasitoids that are known to contribute to the control of Halyomorpha halys. The number of progenies, particularly females, is important for the efficient mass rearing of species used in augmentative biological control programs. Cold storage is an important technique for extending the shelf life of natural enemies used in such programs. Methods: We assessed how fecundity, sex ratio, lifespan, and the number of hosts parasitized within 24 h were affected by host density for T. japonicus and T. cultratus when offered fresh H. halys eggs and how these parameters were affected if adult parasitoids were first placed in cold storage (11°C in the dark) for 19 weeks before being used for propagation. Results: The fecundity were 110.2 and 84.2 offspring emerged at 25°C, for parasitoids not placed in cold storage; among the offspring that emerged, 82.6% and 85.6% were female for T. japonicus and T. cultratus, respectively. If first placed in cold storage, T. japonicus and T. cultratus produced 35.1 and 24.6 offspring per female, respectively, although cold storage significantly extended the shelf life. The survival rates of parasitoids that were placed in cold storage were 90.3% and 81.3% for females, and 3.2% and 0.9% for males of T. japonicus and T. cultratus, respectively. The number of hosts parasitized within 24 h was not shown to be density dependent, but it was significantly lower after cold storage. https://doi.org/10.3389/fphys.2023.1102216