Effect of ozone and calcium lactate treatments on browning and texture properties of fresh‐cut lettuce

Abstract

The effects of three treatments, 1 mg L −1 ozone at 18-20 • C, 15 g L −1 calcium lactate (CLac) at 50 • C and a combination thereof, were compared on fresh-cut lettuce over 10 days of refrigerated storage. Respiration rate, browning and texture were examined as main quality indicators. The use of ozone produced a significantly (P < 0.05) higher oxygen decline than the use of CLac (from day 3 to day 10). At the end of storage, CLac (alone or combined with ozone) samples had higher oxygen content (∼9%) than ozone samples (∼6%). Enzymatic activity decreased significantly (P < 0.05) in ozone samples. Polyphenol oxidase activity in fresh-cut lettuce treated with ozone (alone or combined with CLac) showed lower values on day 1 (<2500 units g −1 ) and at the end of storage (<3000 units g −1 ) than CLac samples (4000-4800 units g −1 ). Ozone also reduced peroxidase activity to ∼300 units g −1 after treatment. Finally, pectin methylesterase activity was also reduced with ozone, showing a negative effect on textural properties. Data suggested that CLac maintained quality markers better than treatments with ozone and ozone/CLac combination over 10 days of storage. INTRODUCTIONConsumers increasingly require food products that preserve their nutritional value, retain a natural and fresh colour, flavour and texture and contain fewer additives such as preservatives. 1 Recent research has underlined the importance of fruit and vegetable consumption to health and has reported new techniques to preserve the nutritional and sensory qualities demanded by consumers.Even though fresh-cut produce has been sold since the 1940s, the quality is unpredictable and the shelf life limited. The extension of quality retention for fresh-cut products is relevant for the industry owing to its economic impact. It is important that the washing treatments applied to fresh vegetables help maintain their quality, since consumers demand a fresh product as well as convenience and long shelf life. 2 Tissue browning is one of the major causes of loss of quality of fresh-cut vegetables. Browning is influenced by the concentration of phenolic compounds and by other factors such as the activity of polyphenol oxidase and peroxidase enzymes. Wound-induced loss of cellular compartmentalisation of phenolic compounds (mainly in the vacuole) and polyphenol oxidase (in the cytoplasm) results in tissue browning at a rate that increases with temperature and water loss. 3 The other cause of quality loss is decrease in firmness.

Changes in Headspace Gas Concentration Including Volatiles as Affected by Post-Harvest Treatments in Packaged Fresh-Cut Lettuce

“…1). Equilibrium among O 2 and CO 2 concentrations developed within 8 days of storage in treatment T 5 (15gL -1 calcium lactate at 50 0 C followed by ozonated water @1.2 mgL -1) which was found substantially different from other treatment due to low rate of respiration, less ethylene evolution which was supplemented with inhibitory effect of ozone on oxidase enzyme activities as reports by Zhang et al, (2005) in fresh-cut celery and Rico et al, (2006) in fresh-cut lettuce.…”

“…An increased storage temperature enhances the metabolism and respiration rate, which may lead to a decreased O 2 concentration and an increase in the CO 2 level inside the package which may result in the accelerated deterioration of plant tissue and may induce off-odors (Ballantyne et al, 1988). However, numbers of many other preservation techniques are currently being used by the fresh-cut industry such as antioxidants, chlorines and modified atmosphere packaging (MAP) (Allende and Artes, 2003) different packaging material and cold storage, MAP, controlled atmospheric storage, UV-C illumination, ozone bubbling as antimicrobial and anti-browning agents, calcium as firming agent and Allicin as antimicrobial agent, which could be a solution to delay such quality losses and extend shelf life and freshness of minimally processed lettuce (Rico et al, 2006;Allende et al, 2009;Karaca et al, 2014 andEscalona et al, 2007). This research compared the effect of postharvest treatments on head space gas concentrations including volatiles of fresh-cut lettuce stored under refrigerated conditions (5±1 0 C).…”

Effect of Modified Atmosphere Packaging on Headspace Gas Concentrations Including Volatiles and Sensorial Attributes of Fresh-Cut Lettuce

“…Fresh-cut products are commonly consumed directly from the bags without any further rinse, a convenience that is one of the main reasons for the growing popularity of these products (Rico et al, 2006). The beneficial effect has been attributed to non-essential food constituents, phytonutrients that pose a relevant bioactivity when frequently consumed as a part of regular diet (Steinmetz and Potter, 1996).…”

Effect of soaking in noni (Morinda citrifolia) juice on the microbiological and color behavior of Haden minimally processed mango

“…Cutting or slicing operations induce a reduction in shelf life by modifying the metabolic processes of vegetal tissue and increasing its susceptibility to spoilage (Raybaudi-Massilia et al 2009) and browning reactions as a result of the compartmentalization loss of phenolic compounds (mainly in the vacuole) and polyphenol oxidase (in the cytoplasm) (Sapers and Miller 1998;Soliva-Fortuny and Martín-Belloso 2003;Rico et al 2006;Del Nobile et al 2009). …”