Optimization of temperature, relative humidity and storage time before and after packaging of baby spinach leaves using response surface methodology

Second-order polynomial models were used to relate the independent variables, temperature, relative humidity and storage time, to the quality attributes (electrolyte leakage, chlorophylls, weight loss, humidity and headspace gas composition inside packages before and after packaging) of ready-to-eat spinach leaves. Results show that while waiting for processing the best conditions to assure high quality spinach leaves before packaging were 4 °C, 83 % RH and 4 h. The weight loss of spinach leaves was time-dependent: increasing the exposure time under these conditions decreased the amount of wet leaves before packaging. Under the same conditions, the electrolyte leakage was lower (4.63 %) and the chlorophyll content (45.44) was higher. After packaging and while waiting for dispatch, temperature most affected the package headspace atmosphere. Indeed, an increase in storage temperature from 3 to 7 °C led to a significant increase in respiration. The best combination of conditions in the high-care room was 3 °C, 74 % relative humidity for a maximum of 1 day before dispatch. In this case, the moisture content (0.46 %) and electrolyte leakage (4.16 %) were lower and the chlorophyll content (43.37) and oxygen concentration inside the packages of ready-to-eat spinach leaves (19.55 kPa) were higher.