• Energy Research

Preserved eggs (pidans) are used in traditional Chinese cuisines. However, the alkaline conditions and metal ions generated during its preparation have caused some concerns. This study developed an innovative process for pidan processing using incinerated eggshell powder, an abundant by-product that can generate a highly alkaline solution and provide calcium ions (Ca2+). Either 0.5, 3, or 5% of the eggshell powder solution was used for basic pickling. Different combinations of ZnSO4 (0.175%), MgCl2 (0.08%), and CuSO4 (0.16%) were added. Duck eggs were pickled for 25 days at 25–27 °C, followed by 14 days of ripening. The pidan processed in 5% eggshell powder containing 0.175% ZnSO4 demonstrated the closest physiochemical and sensory characteristics to commercial pidans. Thus, the results offer a new technique to manufacture pidans and reduce the harmful impact of metal ions on human health and the environment.

Seabass (Lates calcarifer) is one of the top farmed and raised fish in Taiwan, and fish scales are the main by-product after processing. Fish scales contain high amounts of collagen, which can chelate with minerals and enhance mineral absorption in the human body. Hence, fish scales from seabass were enzymatically hydrolyzed to obtain seabass scale collagen peptide (SBSCP). Calcium, the most consumed mineral supplement, was chelated with SBSCP to form SBSCP-Ca. The optimal conditions for chelation were a peptide/calcium ratio: 1:1 (w/w), pH 5.0, and 50 °C for 20 min. The conjugated sites were carboxyl and amino groups based on Fourier transform infrared (FTIR) spectroscopy. Scanning electronic microscope/energy-dispersive X-ray spectroscopy (SEM/EDS) evidently showed the alternation of SBSCP’s molecular structure after chelation and increased concentrations of metal ions. SBSCP-Ca was stable up to 90 °C and from pH 2.0 to 5.0. The retention rate was 70%, as determined after in vitro digestion. The extracts of blackcurrant or berry-grape seeds were added to neutralize the fishy odor and provide antioxidant ability for commercialization. This is the first complete study of the characteristics of SBSCP-Ca as well as their commercialization.

The consumption of fresh produce is steadily increasing and chlorine washing is the most commonly used method of disinfecting fresh produce. However, chlorine washing possesses a potential risk. Hence, this study used ozone microbubble (OMB) water to disinfect Salmonella Enteritidis, S. Typhimurium, Staphylococcus aureus, and Escherichia coli on tomatoes. After injecting ozone into the microbubble generator, OMB was fulfilled in a 10 L tank for 10 or 20 min. The inoculated tomatoes were washed for 30 or 60 s. Control groups included unwashed, water-washed, microbubble-only, and ozone-only. The microbial populations were significantly lower on the OMB-treated tomatoes than controls (p < 0.05), but not between various fulfilling or treatment time (p > 0.05). When tomatoes were treated with OMB with 10 min fulfilling and 30-s washing, the differences of tested bacteria and water washing, ozone-only, and microbubble-only were: S. Enteritidis: 4.11, 3.37, 2.54 log CFU/tomato; S. Typhimurium: 4.83, 4.50, 2.78 log CFU/tomato; E. coli: 4.31, 4.08, 2.09 log CFU/tomato; S. aureus: 4.12, 3.93, 2.82 log CFU/tomato. In addition, significant higher ozone concentrations and conductivity were detected in OMB water than other groups (p < 0.05). Color, texture, and sensory characteristics of the OMB-treated tomatoes were not significantly different from other groups (p > 0.05). This study demonstrated that OMB effectively inactivated bacteria on tomatoes and did not affect the physical and sensory characteristics of tomatoes.