Impact of different calcium dips and solution pH on quality of ready-to-eat baby-leaf spinach

The effect of calcium application and solution pH on ready-to-eat (RTE) baby-leaf spinach (Spinacia oleracea L.) texture and structure preservation was studied. Spinach leaves were treated with calcium chloride, calcium lactate and calcium propionate, at two different pH conditions (5 and 7), packaged and stored for 7 days at 5 °C. After 24 h, the leaves crispness increased 49 and 29% for leaves treated with calcium chloride and lactate at pH 5 and the elasticity increased 100% after calcium propionate treatment at pH 7. During spinach shelf-life, the tissue flexibility decreased (20–60%) for all calcium treatments at pH 5 and 7 while tissue crispiness increased (7–40%) only for calcium treatments under pH 7. The electrolyte leakage increased throughout storage and was higher for all calcium treated samples when compared with controls. The chlorophyll content slightly decreased (12%) by the end of product shelf-life and did not differ according the calcium treatments. Total vitamin C content was lower in leaves treated with calcium chloride at pH 5 (31%) and pH 7 (19%) while the remaining treatments did not affect vitamin C content. The different calcium additives tested for potential texture quality maintenance did not provide the expected benefits on baby spinach leaves but increasing solution pH from 5 to 7 lead to an increased firmness by the end of shelf-life.