Development of smart chitosan-sodium alginate aerogels containing carbon dots/extract obtained from Persian cornflower petals

With the increased awareness on the freshness of food products among consumers, the smart packaging that can track the freshness of packaged foods in real-time by observing the color changes of packaging materials are gradually drawing more and more attentions. The objectives of the current experiment were to fabricate chitosan-sodium alginate (CS-SA) aerogels containing carbon dots/extract (PCE) obtained from Persian cornflower and to investigate the possible utilization of smart aerogels to track the minced lamb meat freshness over a 5-day period at chilled conditions. The CS-SA + carbon dots 0.1%, CS-SA + PCE 3.5%, and CS-SA + carbon dots 0.1% + PCE 3.5% aerogels had significantly higher compressive stress value, water absorption capacity, moisture content, and water vapor absorption capacity in comparison with the control group, recorded by 7.56-20.14 MPa, 13.42%-27.40%, 0.27%-0.56%, and 10.25%-33.90%, respectively (P < 0.05). The colors of CS-SA + PCE 3.5% and CS-SA + carbon dots 0.1% + PCE 3.5% aerogels as pH-sensitive indicators were red, dark violet, green, and yellow-brown at pH 1-6, 7, 8, and 9-10, respectively. The total mesophilic bacterial count, total psychrotrophic bacterial count, pH, and total volatile basic nitrogen compounds of minced lamb meat were determined to be 7.43 log CFU/g, 7 log CFU/g, 7.33, and 27.80 mg N/100 g on day 5 of storage conditions, respectively. The color response of CS-SA + PCE 3.5% and CS-SA + carbon dots 0.1% + PCE 3.5% aerogels as a result of lamb meat deterioration from khaki to violet can also be easily perceived. The results suggest that the fabricated aerogels have great potential to be utilized as intelligent indicators to control the freshness of minced lamb meat.