Processing of minimally processed vegetables – Determination of CCPs.
The flow diagram of minimally processed vegetables is described in Fig. 2, where the CCPs of RTU vegetables are shown
Raw materials receiving – CCP1
During this stage, macroscopic control is carried out to determine their suitability (presence of foreign matter, soil, stones, etc.). This is the first CCP which is the temperature of raw vegetables that should be lower than 5 °C.
Storage – CCP2
Storage is carried out under controlled conditions. Product temperature and relative humidity should be monitored and kept to the minimum.
Macroscopic control
At this stage macroscopic control of vegetables ready to be cut is carried out so that they do not present any perturbations on their surface and their temperature is checked, a critical factor for their quality and shelf life.
Prewashing and preparation
Sorting is carried out at this stage where dirt and outer layers are removed from the surface of the vegetables. Following that, vegetables are cut into slices or small pieces and their prewashing follows.
Cutting
Second cutting is carried out with rotating drums at the desired size. Cutting knives should be adjusted regularly and disinfected at every product change.
First washing and disinfection – CCP3
RTU vegetables are washed effectively and disinfected with biocides. This process reduces the initial microbial load and minimises the pathogenic microorganisms. Water is used, however, its effectiveness is improved by the addition of biocides (chlorine, citric acid-ascorbic acid). Water should be free of foreign matter, temperature of 1–4 °C, and concentration of disinfectant solution at 100 ppm Cl2.
Second washing
Following first washing products go to the second washing machine of the line where they get washed with clean water before going to the drying machine.
Drying
Excess water is removed from the surface of cut vegetables by centrifugation or product placement on the air. Drier should be checked regularly so that no humidity is evident on the surface of cut vegetables.
Packaging – CCP4
RTU vegetables are packaged in semipermeable membranes where due to respiration they modify the atmosphere. Modified atmosphere packaging is used and the gases used are Ο2, CΟ2 and/or N2. Flow pack machines, vacuum or even vertical line machines could be used. The temperature of semi processed product should be checked so that it does not exceed 5 °C, concentration (%) of Ο2, CO2 inside packaging of final product, resistance in vapour permeability, and the ability of thermal welding of packaging.
Labelling–Metal detection–Paletising
During labelling, production date, expiry date, lot number, name and type of the product as well as nutritional information for the consumers are labelled on the package. Metal detection then follows for the presence of metal pieces (>0.8 mm) and if found they are immediately removed. Casing and palletising then follows and cartons are ready to be loaded.
Storage and product distribution – CCP5
Following paletising product is stored in refrigerators (4–6 °C), until loading in tracks operating under the same temperature.
Determination of CCPs in RTU vegetables – Decision tree
The CCP Decision Tree is a tool used to determine the right CCPs for each processing stage. However, according to Wedding (1999a), it is not the perfect tool and cannot replace common sense and processing knowledge and can sometimes lead to false conclusions. This can be seen in Table 1. In Table 2 CCPs, critical limits, process control, corrective actions and verification in cut vegetables have been described.