TECHNOLOGICAL STEPS FOR PREPARATION OF VEGETABLES FREEZING Proff. D-r LiuboVrachar Technological faculty of Novi Sad, Serbia
Vegetable`s preparation • - Vegetables meaning is based on vegetative and generative parts used for livelihood of the people in fresh and processed type. • - Their rich content of nutritional and protective substances makes them inseparable part of the today`s system of healthy nutrition. • - The production and consuming of fresh and processed vegetables today takes part of the fully food production. • - More precisely the production of vegetables represents one of the most intensive and profitable branches of agricultural product`s processing which can be proved of the yield of one unit surface, employment of labor, economical effects, etc. • - According to recommendations of the World Healthy Organization in the today`s energy balance structure the vegetables must participate at 12% and according to Agricultures Department of the USA – with 18% up to 20%
According to its similarity and botanical characteristic the nutritional and physiological value it is approved the following vegetable`s classification: • - roots (carrots, beet, celery, parsnip, potatoes) • - onions (onion, garlic, leek) • - stem vegetables (asparagus) • - leaf (spinach, salad,cabbage, leafs ofcelery and parsley) • - color (cauliflower, broccoli, artichoke) • - seeds and fruits (peas, green bean, tomato, eggplant, pepper, zucchini, cucumbers, watermelon and melon , sweet corn) • - dry legumes (dried beans, lens, dry peas)
- The production and the regular supply of the customer with fresh vegetables during the year is connected with the season production and also with the ability of the vegetables to spoil fast because of their high water content and that makes them perishable. • - In the technological process the production and processing of vegetables inevitably includes adequate process of vegetable`s conserving. /protection/
- The vegetables which are intended for industrial processing meets the following requirements: • - must be in the optimal phase of ripeness and to be fresh • - must not be dirty, wet or rotten • - must not contain pesticide residues in quantities which are dangerous for customer`s health • - must not have bad smell and to not contain strange impurities • - must not be hurt or damaged in way to damage the final quality • - From technological and physiological point of view many types of vegetables today are conserved qualitatively in low temperatures using the method of freezing. • - Today is accepted that the freezing is one of the most quality way for conserving vegetables. • - Depends on the physiological specialty, consistency and the fruit shape the phase of ripeness, the propose etc., the vegetables can be frozen in three categories: • - individual frozen whole vegetables: peas and sweet corn, a pepper, brussels sprouts, mushrooms etc. • - chopped vegetables, individual frozen: chopped green bean, chopped pepper, chopped roots, chopped onion, mushroom and leek.etc. • - chopped frozen vegetables( mash):spinach, pepper, carrots, tomatoes, pumpkin
- During the technological process of vegetable`s preparation for freezing for every kind there are specific feature just like as some categories. • - There are included different technological operations which separates foreign bodies, vegetables which are unfit for processing, reduces microorganisms and deactivates the enzyme system, also are developed positive organoleptic qualities etc. • - This can be done via including of different technological operations like : washing and selecting, calibration, cutting, peeling, primary technical processing ( blanching), blending etc. • - The importance of the freezes vegetables for the healthy nutrition and the economical aspect of their production are the cause for the intensive development of the technical process in cooperation with the science and practice.
PEAS • - It takes part of the well known group species and there are more than 5000 sorts • - It grows under moderate continental climate отглежда with dynamic of the harvest – in the Balkans – 22-25-30 days depends on sorts, early, middle late, the dynamic of the sowing and above sea level. • - In our regions ( today the system irrigation of is always used) can be reach yield to 6 to 10t/ha peas. • - The young grain of peas is distinguished with high nutrition valor and wide usage for quality nutrition. • - For saving the peas via freezing it is convenient fine-grained sorts with equial dimensions and tenderometriya of`120 T°. • - Like common rule it is accepted that in all of the peas sorts and in all of the growing conditions that with increasing of the ripeness level it is increased also and the yield but it comes decreased the technological valor of the grain. • - In the optimal technological ripeness the peas is with the highest content of sugar, nice sweet taste and tender consistence.
- To definite the level of the ripeness of the peas its with priority importance and can be defined: • Chemical method • Physical method • Morphological method • Chemical method –defining of the starch, sugar and non dissolvable in water substances. (ANS) • Physical method – defining of the physical volume and the level of the Tenderometriya`shardenss. • Morphological method – proportion grain/pot • - If it`s necessary the peas grain can be stored a few days under the temperature of 0 to 2C and relative humidity – 80-90% • - the process of the peas preparation and freezing is described in the following block scheme.
-Тhe key operation of blanching is made for: • Deactivation of the enzymes • Reducing the micro flora • Evacuation of the air in the intercellular area. • Equally softening of the grain • It receives “cleaner” color (peas,green bean, broccoli, cauliflower, asparagus) • Removal of the harmful substances, which gives unpleasantsmell and taste of crude • It reduces the vegetable`s volume • It reduces the lost of Vitamins A,B,C in the period when it is sorted. • The regime of blanching is under the temperature of 85-90 C and time of 5 minutes , which is checked by the test named peroxides and it must be negative. • - The frozen peas must be stored in refrigerated to - 20C and up to 12 months.
Green bean • -The green bean is one of the most important agricultural species for the conserving industry in many countries. • -On the Balkans it is cultivated on first(spring) and second harvest. • - For nutritional purposes it is used the yellow and the green bean of pots – technological grown – until it is juicy and soft, without parchment layer and thread. • -From the spring harvest the green bean comes processed during July and from the second harvest – during the second half of September with yield of 8 to 15 t/ha. • The harvesting of the crop starts in optimal technological ripeness, which is defined by the following methods: • Physical method – with help of the tenderometriya or tekstometriya • Chemical method– defining of ANS/ non dissolvable in water substances / • Morphological method– proportion grain/pot • - It is accepted that the pot is in it`s optimal ripeness when the grain in the pot is big as the wheat grain – it not exceed 10% of the pot`s volume, it doesn`t have cellulose fibers, the rip is juicy and crispy and it crackle a little bit when you try to broke it.
-For the green bean processing, as for the peas too, today it is used mechanized technological lines which can assure the fast, the permanent and equal production. • - The prepared pot can be frozen cutted across(2,5 tо 3 cm), longitudinal or whole depending on it`s purpose. • -The blanching which is very important operations can be committed under the temperature of 85 oC for 3 to 5 • - The frozen bean is kept in refrigerator from – 20 C and can be stored for 12 months. • - The technological process of freezing of the green bean is performed as the following technological scheme:
Sweet corn • -Depending on corn`s sorts on the Balkans the crop of the sweet corn is harvested between the 70 and 90 days with yield of 8 to 12t/ha. • -The sweet corn is distinguished with high nutritional and biological valor, which can be reached by passing through milk phase to ripeness – the grain is well developed but it still not contain milk liquid. • - The valor of the ripeness is subjective defined – the color or with nail push or with objective method via: • Defining of ANS/ non dissolvable in water substances • Specific volume of the grain • - The period for growing from harvesting of the field to processing is in directly dependence of the temperature: • to 0°C 6-8 days • to 5°C 3-5 дни • to 10°C 2 дни
- The processing of the sweet corn today is totally mechanized . The harvesting of the crop through the package is worked on line with modern technological lines as applied technological scheme. • -The blanching is very important operation and it comes performed in temperatures from 88 to 90°C for 3 to 5 minutes. • - The frozen sweet corn can be stored successfully under the temperature of 20 C for period of 12 months.
Pepper • -Because of its high nutritional and biological valor the pepper is one of the most significant species. • - It gives high yield of one unit and it takes big labor work. • - Depends on the sort or of the agro ecological conditions and other factors it may be reached harvest from 15 to 30 t/ha. • - For quality nutrition of the people the pepper is with wide application and big valor. • -Its chemical construction with exceptional organoleptic properties makes the pepper irreplaceable part of the daily diets.. • - Apart from the industrial processing it is wide developed the specter of traditional processing of the pepper in home conditions. In the nature there are a few vegetables with that wide application as the pepper. • - The pepper is harvest manually with its stem in a few passing through the field – 3 to 5 times. • - Depends on the sort and the application the pepper can be harvested in technological or physiological ripeness.
- The technological ripeness of the pepper is characterized with fully formed fruit according to sort`s characteristics. • - In the processing it is looked for the pepper which is ripped and its physical ripeness mach the physiological ripeness. • -The Carefully harvested pepper, adequate packed, can be stored successfully for 15 days in the storages with controlled temperature and up to 40 days in storages with temperatures from 0,5 do 0,5 oC and humidity 85 до 95 %. • -For freezing it is used peppers with expressed color, as fat as it can “meat”. The best sorts which meet this requirements are kapiya and Babura. • - Depends on the pepper`s applications it can be whole frozen, cutted orshredded pulp. • - The quality frozen pepper in all of the shapes can be stored up to 12 months. • -The technological steps for freezing the pepper are shown on the scheme below.
Spinach • -It is liken because of the green, fresh leafs withwide use in the household and in the industrial processing. • - The spinach takes well the low temperatures which is very important for the dynamic of processing and permits early in the market the appereance of fresh spinach and also to be freezed which permits prolongation and widening of the refrigerator`s work season. • - The spinach`s yield may varies between 10 to 25 t/ha. • - The gather of the harvest starts when the spinach has 5 to 6 big leafs. • - For mechanized gather and industrial processing are recommended sorts with face rosettes. • - The mechanized gather starts when the spinach if 5 cm over the ground • - The time from the haymaking to processing must be as shortest as it can – not longer than 7 to 8 hours. • - If it`s necessary the spinach can be stored for 15 days in refrigeratory at temperature from -0.50 to 0,5 oC , and humidity 90 to 95%
The spinach is typical leaf vegetable which can be frozen successfully in one of the following ways: • Spinach leafs– whole leafs, cleaned from the root • Spinach, cutted– cut in to leafs with length 20 mm at the shortest segment • Chopped spinach – pieces from 10mm to shorter • Spinach pulp – blended spinach with pieces smaller than 3 mm • - The blanching of the spinach happens with constantly acting, special blanching tools with directly steam evaporation. • - The regime of the blanching in under the temperature of 90 oC for 3 to 5 minutes. • - The frozen spinach must be stored in the temperature from - 20 oC up to 12 months. • The technological steps for preparation of the spinach can be seen in the following scheme
ROOTS • -The most often type of frozen roots are the following: carrots, potato, celery, and sometimes. • - The technological process and preparation for the root`s freezing is shown on the application below. • - During the preparation of the roots the main operations are peeling, cutting and blanching. • - The peeling usually comes in thermo – physical way, they are diced, chopped in segments or streak and the blanching is accomplished in constantly working blanching tools in temperature 88 С to 90 С for 3 to 6 minutes.