preservation techniques of fruits and vegetables pdf

Preservation Techniques Of Fruits And Vegetables Pdf

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Processing and Preservation of Fresh-Cut Fruit and Vegetable Products

By Afam I. Jideani, Tonna A. Anyasi, Godwin R. Mchau, Elohor O. Udoro and Oluwatoyin O. Fruits and vegetables are plant derived products which can be consumed in its raw form without undergoing processing or conversion.

Fresh-cut fruits and vegetables FFV are products that have been cleaned, peeled, sliced, cubed or prepared for convenience or ready-to-eat consumption but remains in a living and respiring physiological condition. Methods of preserving FFV to retain its wholesomeness includes washing with hypochlorite, hydrogen peroxide, organic acids, warm water and ozone for disinfestation and sanitization; use of antimicrobial edible films and coatings; and controlled atmosphere storage and modified atmosphere packaging of fruits and vegetables.

Exposure of intact or FFV to abiotic stress and some processing methods, induces biosynthesis of phenolic compounds and antioxidant capacity of the produce. Conversely, loss of vitamins and other nutrients has been reported during processing and storage of FFV, hence the need for appropriate processing techniques to retain their nutritional and organoleptic properties.

FFV are still faced with the challenge of quality retention and shelf life preservation mostly during transportation and handling, without impacting on the microbiological safety of the product. Hence, food processors are continually investigating processes of retaining the nutritional, organoleptic and shelf stability of FFV.

Postharvest Handling. The importance of fresh-cut produce lies in its major characteristics of freshness, convenience, nutrient retention and sensory quality while providing extended shelf life [ 3 , 4 ].

Fresh-cut fruits and vegetables FFV are products partially prepared and which require no additional preparation for their use. This makes it unavoidable that their overall quality diminishes during processing and storage. It is made more so, as the operations involved in preparing fresh-cut products damage the integrity of the cells, promotes contact between enzymes and substrates, increases the entry of microorganisms and creates stress conditions on the fresh-cut produce [ 4 , 5 ].

According to Artes-Hernandez et al. Fresh-cut products are also reported to contain similar nutrients and ingredients as whole products with the added advantage of short time preparation and the low prices at which they are been sold [ 7 ].

Fresh-cut products constitute a major rapidly growing food segment which is of interest to food processors and consumers. The fresh-cut industry is expanding more rapidly than other sectors of the fruit and vegetable market due to its supply of both the food service industry, retail outlet as well as its expanding production and access to new markets across the globe.

The growth rate of the sector is reported to be in the region of billions of dollars in recent years with USA as the main producer and consumer while the UK and France follows after [ 6 ].

Despite the fact that food processing methods extend the shelf life of fruit and vegetable products, processing of fresh-cut produce however reduces the shelf life of the commodity, rendering the product highly perishable as a result [ 6 ].

This biological changes may lead to flavour loss, cut-surface discolouration, decay, rapid softening, increased rate of vitamin loss, shrinkage as well as shorter shelf life of the fresh-cut produce. Interactions between intracellular and intercellular enzymes with substrates as well as increased water activity may also lead to flavour and textural changes upon processing [ 8 ].

A major effect of fresh-cut processing is stress on vegetable tissues with the resultant phytochemical accumulation and loss induced through reduced activity in key enzymes of secondary metabolic pathways.

Fresh-cut processing also results in cell breakdown as well as the release of intracellular products such as oxidizing enzymes thereby quickening product decay [ 2 ]. Several factors are reported to affect the overall quality of fresh-cut produce.

Among many of such factors is appearance [ 1 , 9 ]. Appearance according to Kays [ 10 ] and Lante and Nicoletto [ 11 ] in combination with size, shape, form, colour as well as the absence of defects are factors which greatly affects the purchase of fresh-cut produce by consumers.

All of these factors can also be influenced by several pre-harvest factors. Research has also shown that regular consumption of fruits and vegetables reduces risk of cancers, cardiovascular diseases and several inflammations [ 12 , 13 ].

This apart from regular body exercise and genetics has made fruit and vegetable consumption one of the main factors that contributes to a healthy lifestyle. With studies showing the nutritional benefits of fruits and vegetables, consumption of FFVP therefore promotes health through increase in the supply of antioxidant and other phytochemical nutrients to the body.

FFV have been known to have a shorter shelf-life compared to intact fruit and vegetable products due mainly to processing. Several processes involved in the production of FFVP have been known to alter greatly the shelf stability of the cut-produce. Shelf life extension of the cut produce is therefore dependent on a combination of these unit operations as well as proper temperature management during storage, use of antibrowning agents, proper packing conditions as well as good manufacturing and handling practices [ 6 , 7 ].

Unit operations and maximum recommended temperatures for each step in the processing of fresh-cut fruit and vegetable produce. Adapted from Artes-Hernandez et al. An essential aspect of processing of fresh-cut produce is cutting.

Cutting helps divide whole harvested fruit and vegetable products into minute fractions before packaging. The effect of cutting however on the products is the wounding stress which the cut tissues are allowed to suffer thus accelerating the rate of spoilage and deterioration of the cut produce [ 14 ]. Cutting has been attributed to be the main factor responsible for the deterioration of FFV thereby enabling the product to experience a more rapid rate of deterioration than whole products [ 15 ].

Cutting increases respiration rate [ 16 ], induces deteriorative changes associated with plant tissue senescence and thus the consequential decrease in shelf life when compared to the unprocessed produce [ 4 ]. The works of Portela and Cantwell [ 19 ] showed that melon cylinders cut with a blunt blade demonstrated higher ethanol concentrations, off-odour scores, electrolyte leakage, and increased potential for ethylene secretion when compared to products processed with a sharp blade.

It was also reported that use of sharp cutting implements reduces wound response, lignin accumulation, white blush, softening and microbial growth in fresh-cut carrots [ 18 , 20 — 22 ]. Cutting-induced injury has been implicated as affecting the immediate visual quality of fresh-cut products and has also been known to have longer-term effects on metabolism with the concomitant quality changes that are detected at a later time.

The actual cutting process results in great tissue disruption as formerly sequestered enzymes and substrates mix are found to mix, hydrolytic enzymes released, while signalling-induced wounding responses may be initiated [ 23 ].

During the process of cutting, phenolic metabolism takes place: breakage of the plasma membrane with the resultant effect of inducing oxidative enzymatic reactions thus triggering browning of tissues and oxidation of polyphenols [ 14 , 24 ]; and production of injury signals which induces the secretion of more secondary metabolites including phenolic antioxidants to heal the wound damage [ 14 , 25 , 26 ]. It has been reported that the content of phenolic acids increases in fresh-cut products.

This fact can be attributed to the cutting of fresh fruits and vegetables with knives thereby inducing the activity of polyphenol oxidase PPO in the cut fresh fruit and vegetables. FFV are thus easily susceptible to browning reaction as a result [ 27 , 28 ]. Accumulation of phytochemicals can also be as a result of altered O 2 and CO 2 levels during packaging as well as the use of preservatives such as [ 14 ] ascorbic and citric acid [ 28 — 31 ].

Wounding as a result of cutting has been attributed as one of the basic source of stress experienced by fresh-cut produce. Some factors can however affect the wound response of the fresh-cut produce and these factors include stage of maturity, cultivar, storage, processing temperature, cutting method, water vapour pressure as well as O 2 and CO 2 levels [ 18 , 19 ].

According to literature, wounding stress as a result of cutting of fruit and vegetables has been shown to increase the antioxidant activity as well as the polyphenolic content in fresh-cut produce such as carrots [ 32 , 33 ], celery [ 34 ], lettuce [ 35 ], broccoli [ 36 ], mushroom, onions, and mangoes [ 37 ].

Consequences of wounding includes increase in respiration rate; production of ethylene; oxidative browning; water loss; and degradation of membrane lipids [ 4 , 5 ]. This therefore increases the susceptibility of FFV to increased perishability than their source commodity [ 38 ]. During the production process, cut fruits are exposed to environmental microbes in the processing facility.

Reducing the level and rate of contamination will be dependent on the use of the appropriate disinfectants and sanitizers. One of such disinfectants of high use in the FFV industry is chlorine. The use of chlorine as a disinfectant is however of great concern and is presently prohibited in some European countries due to issues of public health [ 39 ].

Chlorine is generally used in the food industry due mostly to its low price and its wide application of antimicrobial effectiveness [ 39 , 40 ]. However, under certain conditions, chlorine has been shown to be weak in reducing microbial loads [ 41 ] as it can easily be inactivated by organic matter [ 40 , 42 ] and its action is highly pH reliant.

Chlorine has also been shown to produce unhealthy by-products which are carcinogenic and mutagenic such as chloroform, trihalomethanes, chloramines and haloacetic acids, when reacting with organic molecules [ 43 , 44 ].

Chlorine is also corrosive with its use banned in some European countries such as Belgium, Denmark, Germany and The Netherlands [ 40 , 45 — 47 ]. Presently, alternative chemical compounds, biological methods and physical technologies which are more environmentally friendly and possess less risk to the health of workers and consumers have been developed to replace the use of chlorine [ 45 — 52 ].

Concentrations of 50— ppm and exposure time of 5 min of chlorine is commonly applied as hypochlorous acid and hypochlorite and as disinfectant in the FFV industry in order to enhance microbial safety of the produce [ 1 , 49 ]. In the handling and processing of FFV, common practices are undertaken and needs to be taken note of. These practices consist of protection from damage as a result of poor handling and poor functioning of machinery, foreign body contamination, improper washing, drying and unhygienic practices by personnel.

Hence worker sanitation which is most often neglected in the fresh cut industry in collaboration with good manufacturing practices must be enforced by food processors. In accompanying this process, training of food handlers in food hygiene techniques must be undertaken [ 6 ]. Presently, new and alternative technologies for safety, improved quality and extended shelf life of processed fresh-cut products have been developed.

Such technologies include: ozone O 3 , a strong oxidizing agent in destroying microorganisms which has also been suggested as an alternative to sanitizers due to its effectiveness at low concentrations, short contact times and in the breakdown of nontoxic products; chlorine dioxide ClO 2 , which is known for its efficacy against pathogenic spores, bacteria and viruses; organic acids and calcium Ca salts applied for maintenance of cell wall structure and firmness Ca , inhibition of enzymatic and non-enzymatic browning as well as in the prevention of microbial growth at heights that did not affect flavour of the fresh-cut products with their efficacy against microbes higher for bacteria than molds; electrolyzed water employed due to its strong bactericidal effect against pathogens and spoilage microbes [ 6 ].

It has been shown that fresh-cut process increases the metabolic activity mainly as a result of the enzymes polyphenol oxidase PPO causing discoloration and peroxidase POD causing enzymatic browning as well as de-compartmentalization of enzymes and substrates in tissues causing changes in flesh colour [ 54 ].

PPO can induce the browning occurrence by catalyzing the oxidation of phenol to o-quinones which are polymerized to produce brown pigments. Postharvest techniques maintaining the quality of fresh-cut fruit have been investigated by several researchers [ 55 — 57 ] including physical and chemical treatments.

Many anti-browning agents or mixtures have been investigated like: calcium ascorbate with citric acid and N-acetyl-L-cysteine [ 58 ], citric acid [ 59 ], ascorbic acid with citric acid and calcium chloride [ 30 ], 4-hexylresorcinol with potassium sorbate and D-isoascorbic acid [ 60 ] and modelling of the effects anti-browning agents on colour change in fresh-cut [ 57 ].

They also observed that treatment with L-cysteine or glutathione was effective in suppressing tissue metabolism, PPO and POD activities, while citric acid significantly inhibited the growth of microorganisms. The estimated parameters k and the standard error of estimates S.

Adapted from Techavuthiporn and Boonyaritthonghai [ 57 ]. The unit operation employed in processing of FFV involves peeling, cutting, slicing and shredding; all of which cause disruption of surface cells, tissue and cytoplasm exposure, coupled with high water activity and low pH; thereby providing a breeding ground for growth of pathogenic microorganisms such as Escherichia coli H7, Salmonella spp.

Peeling and cutting of fruits and vegetables removes the protective epidermal layer, thus exposing the product to air and possible contamination by bacteria, molds and yeast. Contamination of produce can occur at any stage from production till consumption. During growth, harvest, transportation and further processing and handling, fresh-cut produce can be contaminated with pathogens from human, animal, or environmental sources [ 40 , 61 ].

Since most FFV are consumed raw without any further treatment, consumption poses a potential health risk in cases where there is contamination. Several outbreak incidences have been documented by Centre for Disease Control and Prevention as reviewed by Ramos et al.

Some of the sources of these microorganisms include soil, manure, silage, sewage, water, raw meat, and domestic animals. Presence of up to 10 4 of Listeria monocytogenes cells can cause food infection with up to 90 days incubation period. Symptoms of its infection includes flu-like symptoms, septicemia, encephalitis, still birth and abortion in pregnant women [ 62 ].

There are a number of factors affecting the microbial safety of FFV and which will be elucidated as follows:. Microbial growth and survival depend largely of the quality or type of fruit or vegetable in question. The quality factors of a product that may affect microbial growth include pH, water activity, respiration rate, type of packaging, competitive microflora and innate antimicrobials [ 61 ]. The pH of a product strongly influences microbial growth.

Despite the acidic pH of most fruits, organisms such as E. Fresh fruits and vegetables provide an ecological niche to some microorganisms; and these vary from one product to another depending on the type of product, climatic conditions, geographical location, harvesting, handling and transportation. Microflora of fruits and vegetables include bacteria such as Erwinia herbicola, Enterobacter agglomerans, Xanthomonas, Leuconostoc mesenteroides , Lactobacillus spp.

Flavobacterium ; and moulds like Penicillium, Fusarium, and Aspergillus [ 40 ]. An antagonistic behaviour of native microflora of fruits and vegetables against pathogenic microorganisms have been reported [ 61 ].

Processing and Preservation of Fresh-Cut Fruit and Vegetable Products

Effective date : Year of fee payment : 4. Year of fee payment : 8. Year of fee payment : Methods of preserving fresh vegetables with a vegetable preservative which extends the shelf life of fresh vegetables, particularly cut fresh vegetables, are provided. The vegetable preservative preserves the texture, flavor, appearance, crispness, and moisture of the fresh vegetables, particularly fresh cut vegetables. In the preferred embodiment, the method comprises the following steps: providing a preservative solution comprising: water, calcium ions; and ascorbate ions, and, applying the vegetable preservative to the vegetable.

See comments. When you preserve food, you are taking action to stop it from breaking down, as it does naturally. You are killing or preventing the growth of microorganisms. Today, we will explore how you can preserve some of the fresh produce you buy or grow. By following a few easy steps, you can still eat those tasty fruits and vegetables when they are out of season.

Best food preservation methods for fresh vegetables

When you click on our product link and buy a product, they pay us a small commission that helps cover some of the costs of maintaining this website. We appreciate any purchase that you make. The best food preservation methods for fresh vegetables depends on their degree of ripeness. To preserve the best quality vegetables, it helps to understand the difference between maturity and ripeness.

Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. Corpus ID: Preservation of fruit and vegetables. James and B.

Summer is the best time of year for those who love fresh fruits and vegetables.

Processing and Preservation of Fresh-Cut Fruit and Vegetable Products

 А-а… Зигмунд Шмидт, - с трудом нашелся Беккер. - Кто вам дал наш номер. - La Guia Telefonica - желтые страницы. - Да, сэр, мы внесены туда как агентство сопровождения.  - Да-да, я и ищу спутницу.  - Беккер понял, что совершил какой-то промах. - Да, наше агентство предоставляет сопровождающих бизнесменам для обедов и ужинов.

Каждый затраханный файл может спасти мир. - И что же из этого следует. - Из этого следует, - Джабба шумно вздохнул, - что Стратмор такой же псих, как и все его сотруднички.

У нее даже перехватило дыхание. Почему. Сьюзан охватила паника. Она быстро проверила отчет программы в поисках команды, которая могла отозвать Следопыта, но ничего не обнаружила. Складывалось впечатление, что он отключился сам по. Сьюзан знала, что такое могло произойти только по одной причине - если бы в Следопыте завелся вирус.

Table of contents

 Не вижу ничего нового, - сказала Сьюзан.  - В чем же чрезвычайность ситуации, из-за которой вы вытащили меня из ванной. Какое-то время Стратмор задумчиво нажимал на клавиши мышки, вмонтированной в столешницу письменного стола. После долгой паузы он наконец посмотрел ей в глаза и долго не отводил взгляда. - Назови мне самое большое время, которое ТРАНСТЕКСТ затрачивал на взламывание кода.

И этот вирус уже невозможно остановить - разве что вырубить электроэнергию и тем самым стереть миллиарды бит ценнейшей информации. Спасти ситуацию может только кольцо, и если Дэвид до сих пор его не нашел… - Мы должны выключить ТРАНСТЕКСТ! - Сьюзан решила взять дело в свои руки.  - Я спущусь вниз, в подсобное помещение, и выключу рубильник. Стратмор медленно повернулся. Он являл собой печальное зрелище.

 Они повсюду! - крикнула Соши. - Присоединяются зарубежные налетчики! - крикнул один из техников.  - Уже обо всем пронюхали. Сьюзан отвернулась от экрана ВР к боковому монитору. На нем бесконечно повторялась видеозапись убийства Танкадо.

Common Ways to Preserve Food

Прошу меня извинить. К человеку в моем положении часто приходят с… ну, вы понимаете. - Да, мистер Клушар, конечно, понимаю. Это цена, которую приходится платить за известность.

Лучшее, что мог сделать директор, - не мешать ему работать и наблюдать за тем, как коммандер творит свое чудо. Стратмор разработал план… и план этот Фонтейн не имел ни малейшего намерения срывать. ГЛАВА 75 Пальцы Стратмора время от времени касались беретты, лежавшей у него на коленях.

Как они смогут ему противостоять. Эти аргументы она слышала уже много. Гипотетическое будущее правительство служило главным аргументом Фонда электронных границ.


Marco H.

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