Session 1: Fruit processing
Cirad-flhor and tropical
CIRAD-FLHOR's mission in the technology and mastery of the quality
of fruits and vegetables is that of being able to provide back-up for the
development of sectors by operating at the level of each player. Contribution
to a better quality local diet, the improvement of growers' incomes and the
better matching of production to markets are sought in a
The themes addressed should lead to:
They are centred on three lines of approach:
The scientific and technical objectives are organised as
research and development projects concerning products covered by the
department: fruits, vegetables, aromatic plants and other horticultural
produce. They concern the following themes:
The international tropical fruit and
citrus juices market: review and perspective.
Although it is difficult to find accurate, reliable statistics, we can nevertheless affirm that the market for practically all citrus juices and all tropical fruit juices is growing slowly but steadily at both the global scale and that of the European Union. The analysis and interpretation of official data and above all permanent contacts with economic operators in the fruit juice sector led us to reaching this conclusion. I shall analyse the European market situation product by product (orange, grapefruit, lemon, pineapple, mango, passion fruit and banana), but it can already be stated that the fruit juice market at the beginning of the twenty-first century is characterised by two new, important trends: 1) business concentration at all levels in the production and distribution chain; 2) the emergence and very rapid development of demand for NFC (Not From Concentrate) and organic products.
Processing exotic fruits for
juice: description of processes and optimisation of qualities
Demand in industrialised countries for juice prepared from exotic fruits has been growing for several years, essentially because of the success of exotic 'multi-fruit' or 'cocktail' juices available as pure fruit juices, juices prepared using concentrate, nectars and fruit juice beverages. The harmonisation of international standards (ISO, HACCP, CODEX), the recognition of European standards (AIJN) and increased awareness of the public and governments with regard to food safety have led producers to optimise their manufacturing processes and quality systems in order to supply increasingly healthy products of good taste quality at a competitive price. Industrial production of juice from exotic fruits thus uses simple principles aimed at healthy, rapid juice production with optimum yield and conservation of the sensorial and nutritional characteristics of the raw material. Significant examples of the optimisation of processes and qualities applied to the manufacture of juices from exotic fruits are presented. Pure Florida citrus juice (orange, white and pink grapefruit): description of pressing procedures and automated aseptic technology producing high quality pure citrus juices. Some of these juices are stored in aseptic tanks with a capacity of 1 million gallons (3.87 million litres). Mango purée from Mexico: presentation of a specific line of mango purées and concentrates packed in aseptic drums. Banana purée from Ecuador: details of the critical points related to banana purée manufacture. Pure pineapple juice from Côte d'Ivoire: presentation of the optimisation of a pressing and packaging line for pure pineapple juice in aseptic cases. Potential for the production of organic pineapple juice. Guava purée from Thailand: examples of physicochemical criteria used in the quality control of raw materials (purées).
Clarification and concentration of
fruit juices using membrane techniques (osmotic evaporation, tangential
The clarification of tropical fruit juices by tangential
microfiltration makes it possible to assemble a large range of new products.
However, in spite of this potential, it is very difficult to clarify fruit
juices with high pulp contents. The combining of filtration and enzymatic
liquefaction is an interesting alternative for facilitating the operation. In
this context, the joint effect of filtration conditions and enzymatic treatment
has been studied mainly in passion fruit juice. An economic strategy was
devised to enable the continuous production of clarified juice. The procedure
can be used for pulpy fruit juices without generating wastes or by-products.
The advantages of immobilisation on a support in a bioreactor in order to
reduce enzyme consumption have also been evaluated.
Application of flash-release, a new
extraction procedure (juice, pulp, essential oil). The example of mango and
Flash vacuum-expansion, a new process for the treatment of plant materials, enables the production of food products (juices, purées, etc.) whose physicochemical and rheological attributes differ from those of products obtained by traditional methods (i.e. blanching, crushing and pulping). Briefly, entire fruits are first steam-heated to 60-90°C and immediately placed in a vacuum chamber (2-5 kPa) where they expand and disaggregate because of the formation of micro-channels inside the tissues by evaporation of water and volatile compounds. Endogenous oxidases are denatured during the steam-heating stage and as the expansion process is performed under vacuum the oxidation and subsequent browning of the products are avoided. Processed materials exhibit higher viscosity than those of traditional products and also differ in colour. This process is increasingly used for pre-treatment of grapes before fermentation in winemaking and for the production of more viscous, better-coloured tomato pureé. Three tropical fruits (passion fruit, guava and mango) were processed by flash vacuum-expansion and further refined. Reference (A) and vacuum-expanded (B) products were then characterized for cell-wall polysaccharides and viscosity and the results were compared. Finally, the process was applied for the extraction of essential oils from citrus peel.
Quality criteria for new
Pineapple, the eighth fruit in terms of world production with
nearly 13 million tonnes per year, is practically monovarietal with the Smooth
Cayenne variety. With the aim of varietal diversification, Cirad-flhor has been
conducting a breeding programme for more than 20 years using in particular
crosses between Smooth Cayenne on the one hand and the Colombian varieties
Perolera and Manzana on the other. Of the 40,000 hybrids resulting from these
crosses and displaying varied characteristics (agronomic performances, fruit
morphology, suitability for cold storage and organoleptic characteristics) only
about ten are currently in the final evaluation phase.
Session 2 : Fruit conservation
Introduction to the storage of
Tropical fruits are increasingly present on European markets and
increasingly familiar to consumers. Their nutritional qualities are praised in
numerous advertisements that encourage housewives to know, choose and purchase
these fruits for their levels of vitamins, magnesium, antioxidants or
Research work covers the following aspects:
The importance of the storage of
tropical fruits under modified atmosphere. Application to mango.
The principle of storage under modified atmosphere (that is to say
that differs from the normal composition of the ambient air) is based on the
one hand on knowledge of the respiratory physiology of the produce to be packed
and on the other on knowledge of the packing material itself (structure,
composition and permeability).
French regulations concerning post-harvest
treatments of tropical fruits and vegetables.
Fruits and vegetables from tropical regions are transported for long distances. This sometimes means long transport times (by sea) and often phytosanitary risks related to the presence of parasites and pests different to those of the consumption zone and that may appear in lists of quarantine organisms. Various chemical natural substances and various techniques can be used to conserve the quality of the fruits and vegetables shipped (appearance, flavour, etc.) and to prevent phytosanitary risks. The substances must be used within a strict regulation framework that is regularly revised according to knowledge concerning these substances and their impacts on the health of consumers or users and on the environment. The regulations concerning the use of chemicals are applied at two levels: entry of the substance in a community positive list and its marketing authorisation awarded to commercial products by each member-state. This concerns only applications performed in the territories of the member-states; the residual level of the product on or in fruits and vegetables. The state of the regulations applied in France is examined with regard to food additives and post-harvest treatments authorised for unprocessed fruits and vegetables and quarantine phytosanitary treatments.
Exotic fruits and vegetables: the
requirements of modern consumption
New consumption European consumers are sated customers with a
profusion of commercial proposals in their towns. And there is no longer any
question of protected areas. The minimum requirements are as follows:
Optimisation of fruit and
vegetable packing under modified atmosphere
The optimisation of the packing of fresh fruits and vegetables under modified atmosphere requires a rigorous approach. It is first necessary to measure the respiratory parameters of the produce (O2 and CO2 respiratory intensities, the respiratory quotient, the apparent Michaelis constant for oxygen, the carbon dioxide inhibition constant and the influence of storage temperature on all these parameters). These measurements make it possible to calculate the respiratory intensity of the produce under all conditions of temperature and atmosphere. The second stage is the determination of the most favourable gas composition for maintaining the commercial and sanitary qualities of the fruits and vegetables concerned. This determination requires storage under controlled atmosphere and the results depend on the weighting of the different deterioration processes. Finally, a mathematical model is used to calculate the optimum permeabilities of the film to be used under the storage conditions entered in the model. Various software is used to simulate storage (the evolution of atmospheres) using the films available on the market and that display permeabilities similar to those previously calculated. At this stage, the functioning of the system can be verified by simulating the thermal profile of a realistic commercial channel. Finally, it is essential to verify these theoretical results by experimental work as no model is yet capable of forecasting all the types of deterioration possible.
New coating formulations for the
conservation of tropical fruits
Shipment and storage of tropical fruits is difficult because they cannot tolerate low temperatures that are often used in the case of temperate fruits to slow down ripening and extend the shelf life. For this reason, tropical fruit are often shipped by air rather than by land or sea, which increases costs to consumers. Edible coatings with moderately low storage temperatures are an economical alternative. Use of polysaccharide coatings on fruit results in a modified internal fruit atmosphere of relatively low oxygen and high carbon dioxide from the combined effects of coating permeability and fruit respiration. This modified atmosphere slows down ripening processes. In addition, all fruits lose water to the storage atmosphere resulting in a shriveling of the peel. This can be reduced by providing a barrier to water vapor, such as a wax or lipid edible coating. Finally coatings can carry antimicrobial compounds, or act as a physical barrier to pathogens, reducing fruit decay. Often coating formulations are composite films made up of combinations of ingredients. Some examples include use of a sucrose ester film (SemperFresh) on loquat, tangelos, pineapple, and banana; carnauba wax on guava and mango; mineral oil on limes; and a cellulose-based film (Nature Seal) on guava, mango, and oranges.
New litchi conservation techniques
Litchi is a fragile fruit that does not keep for a long time.
Stored at ambient temperature, it loses its pinkish red colour in a few days
and browns very rapidly. This classic enzymatic browning is revealed by cell
delocation. Cold results in only a very modest increase in conservation of the
red colour and adjuvants must also be used to maintain the initial colour. The
most commonly used method for preventing browning is the fumigation of fruits
with SO2 a few hours after harvesting.