Protein removal from fish mince washwater using ohmic heating

A static ohmic heating system was developed to remove protein from fish mince (threadfin bream) washwatercollected from a surimi production plant in order to improve water quality. The samples were heated under different electricfield strengths (EFS, 20, 25, and 30 V/cm) until reaching the desired temperature (50, 60, and 70oC), and further held at thattemperature for a certain time (0, 15, and 30 minutes). Heating the samples to 70oC resulted in a better protein removal whencompared to 50 and 60oC. After heating to 70oC, the samples were centrifuged. The analysis of the supernatant obtained showsthe reduction of protein, COD, BOD, TS, and TDS to 42%, 25%, 23%, 44%, and 61%, respectively. The electrical conductivityof the samples showed a linear relationship with temperature and the temperature demonstrated a parabolic relationshipwith heating time. EFS and holding time have no significant effect on protein removal

Improvement of Moist Heat Resistance of Ascorbic Acid through Encapsulation in Egg Yolk–Chitosan Composite: Application for Production of Highly Nutritious Shrimp Feed Pellets

Egg yolk (EY) is an excellent supplement for aquatic animals and has good technofunctionality. Ascorbic acid (AA) is a potent bioactive substance and is essentially added to shrimp feed; however, it is drastically lost in both feed processing and in rearing environments. In this study, AA was microencapsulated in an EY–chitosan (CS) composite. The encapsulated vitamin was then mixed into a shrimp feed mixture to form pelleted feed via twin-screw extrusion. The effects of the EY/AA ratio and the amount of CS on moist heat resistance, production yield, encapsulation efficiency (EE), and morphology of microcapsules were investigated. The molecular interaction of the microcapsule components was analyzed by FTIR. The size and size distribution of the microcapsules were determined using a laser diffraction analyzer. The microstructure was evaluated by SEM. The physical properties of the microcapsule-fortified pelleted feed were determined. The AA retention at each step of feed processing and during exposure to seawater was evaluated. The results showed that the microcapsules had a spherical shape with an average diameter of ~6.0 μm. Decreasing the EY/AA ratio significantly improved the production yield, EE, and morphology of the microcapsules. EY proved to be the key component for moist heat resistance, while CS majorly improved the production yield, EE, and morphology of the microcapsules. The microcapsules showed no adverse impact on feed properties. The loss of AA in food processing and seawater was remarkably improved. The final content of the encapsulated AA remaining in shrimp feed was 16-fold higher than that of the unencapsulated AA

Etude du comportement cinetique de proteases en milieu concentre et en presence d'additifs

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc