Effect of antimicrobial-releasing sachets on some quality characteristics of Mazafti dates during the storage period

Dates, as a valuable and high-quality product, are the most important fruit in south of Iran. The quality of this fruit after harvesting and during the storage period, especially in the outside conditions of cold storage, may be changed due to biochemical and microbial interactions. The purpose of this research is to investigate the effect of cinnamaldehyde, sulfur dioxide, and ethanol in special multi-layer sachets on the quality characteristics of Mazafati during the storage period in cold and ambient temperatures. To conduct the experiment, cinnamaldehyde, and ethanol combined with bentonite and sodium metabisulfite alone were placed in special multi-layer sachets. Inside each package of Mazafati samples (~ 300 g) a sachet was placed in order to evaluate the quality characteristics (weight loss, pH, acidity, total soluble solids, peroxidase and catalase enzymes, microbial tests, and sensory evaluation) of stored samples in refrigerator and ambient temperatures. This research was studied using a factorial experiment based on randomized complete design with 5 treatments (cinnamaldehyde, sodium metabisulfite, and ethanol at 25°C and the control samples at 4 and 25°C) in 3 replicates. The changes related to weight loss, pH, acidity, and total soluble solids in the samples stored at 4°C were lower than the samples with releasing sachets; The highest changes were observed in control samples at 25°C (p<0.05). Among the samples treated with releasing sachets, the lowest pH and acidity changes were observed in the fruit samples treated with cinnamaldehyde and sulfur dioxide releasing sachets, respectively, also the lowest total soluble solids change was observed in the samples treated with sulfur dioxide releasing sachets and ethanol at the end of the storage period. peroxidase and catalase activity were higher in the samples stored at 4°C compared to other samples. Among the fruit treated with releasing sachets, the samples treated with sulfur dioxide and cinnamaldehyde releasing sachets respectively had more peroxidase and catalase activity than other samples. The counts of mesophilic bacteria and fungi of Mazafati samples stored at 4°C on the first day of storage were 2.8 and 3.4 log CFU g−1, respectively, which were significantly higher than the microbial counts of the samples stored at was 25°C (p<0.05). In the treated samples with ethanol, sulfur dioxide, and cinnamaldehyde the microbial populations were less than the detection limit. The panelists gave a lower score to the sample stored at 25°C due to the drier texture, sour taste and aroma at the end of the storage period, and the sample stored at 4°C received a higher sensory score. Among the samples treated with releasing sachets, the highest scores for aroma, taste, and overall acceptance were given to the sample treated with cinnamaldehyde releasing sachet. Storage temperature is an important factor that can affect the quality characteristics of Mazafati fruit during the storage period. In this regard, the least change of these parameters or in other words better preservation of quality characteristics was observed at 4°C. In general, among the investigated treatments and considering the cold storage costs, the use of cinnamaldehyde and sulfur dioxide-releasing sachets at 25°C storage, can be suggested to prevent microbial growth, reduce physicochemical changes, maintain quality characteristics, and ultimately the increase of Mazafati fruit shelf life.