Horticulture industries and waste generation

The horticulture industry embraces the production, processing and shipping of and the market for fruits and vegetables. As such it is a sector of agribusiness and industrialized agriculture.  Industrialized horticulture   also includes the floriculture industry.

Among the fruits, most important fruits are bananas, mango, grapes, papaya, semi-tropical fruits like lychee, guava or tamarillo, citrus fruits, soft fruits (berries), apples, stone fruits. Important vegetables include: potatoes, sweet potatoes, tomatoes, onions and cabbage

In 2013, the global fruit production was estimated at 676.9 million tonnes. Global vegetable production (including melons) was estimated at 879.2 million tonnes China and India being the two top producing countries.

Waste generation in Fruits and vegetable processing industries

Processing (canning, drying, freezing, and preparation of juices, jams, and jellies) increases the shelf life of fruits and vegetables. Processing steps include preparation of the raw material (cleaning, trimming, and peeling followed by cooking, canning, or freezing. Plant operation is often seasonal.

The fruit and vegetable industry typically generates large volumes of effluents and solid waste. The effluents contain high organic loads, cleansing and blanching agents, salt, and suspended solids such as fibers and soil particles. They may also contain pesticide residues washed from the raw materials. The main solid wastes are organic materials, including discarded fruits and vegetables. Odor problems can occur with poor management of solid wastes and effluents; when onions are processed; and when ready-to-serve meals are prepared.

Processing of fruits produces two types of waste - a solid waste of peel/skin, seeds, stones etc -a liquid waste of juice and wash-water. In some fruits the discarded portion can be very high (eg mango 30-50%, banana 20%, pineapple 40-50% and orange 30-50%). Therefore, there is often a serious waste disposal problem, which can lead to problems with flies and rats around the processing room, if not correctly dealt with. If there are no plans to use the waste it should be buried or fed to animals well away from the processing site.

 There is a need for development of cost effective technologies for conversion of these wastes into value added products for cost optimization. Horticultural waste provides ample opportunities for value addition besides providing wealth from waste. Its effective utilization helps in reducing the cost of production of crops besides optimum utilization of biomass. The additional returns that it brings augment the income from farming activity besides providing opportunities for employment and capital formation. In the present context of increasing cost of inputs the farming activity becomes more viable only when the total biomass is effectively utilized per unit input. In the context of climate change and global warming, environment protection is a major concern. Degradation of forest biomass for utilization in various industries can be reduced by utilizing the residues and wastes produced during the farming and processing activities of horticultural crops

Grapes are one of the largest fruit crops in the world, while their processing into juice is definitely a minor reality compared to wine-making. In 2013 the world wine production was 27.42 Mton, with 57 % of production in Europe, followed by Americas (25.7 %), Asia (7.5 %), Oceania (5.4 %) and Africa (4.5 %). The top five wine producers resulted France (4.29 Mton), Italy (4.11 Mton), Spain (3.20 Mton), USA (3.22 Mton) and Chile (1.83 Mton).

It is estimated that during mango processing approximately 32-45% of the weight of mangoes used goes as various forms of waste like peels, pulper waste and stones. Similarly in banana cultivation approximately 65% of  biomass goes as field waste. Ripe banana peel waste constitutes to about 20% while  35-40% of peel waste is generated in banana  ( plantains) chips industry.   Among the vegetables  the waste index of cauliflower is 48-58%. Similarly the crop residues of various crops range from 25 to 50% besides processing waste and post harvest commodity handling waste.

The fact that fruits are rich in nutrients and phytochemicals such as carotenoids, antioxidants, flavanoids has lead to the development of such by-products by popular food processing industries. Grape pomace represents rich source of various tartarates, malates, citric acid, grape seed oil, hydrocolloids and dietary fibre. The waste water generated by fruits and vegetable industries amounts to 2-14m³/t vegetable products, while the cannery waste water goes up to 1-3m³/t fresh fruits.  The biological oxygen demand of the waste liquids is also high reaching 0.28-4.7kg/m³ and 0.18- 3.88kg/m³ respectively. The cannery wastes from pineapple is a good source for the production of phenolic antioxidants by growing the beta glucosidase positive fungi in them. Apple peels posses the highest content of phenolic compounds such as quercertin glycosides,  phloridzin, catechin, procyanidins, phloretins etc. compared with other edible parts of apple.

Renewable biomass  (agro-fibres) as a raw material in composites production and the use of renewable biomass may result in several benefits such as environmental protection and socio-economic dvelopment. Particle board can be produced from wastes of plant stalks, stems and leaves. The fibres from pseudostem of banana is becoming a marketable product in several banana growings states like Bihar, Tamil nadu, Andhra Pradesh and Kerala. Fibre extracted from banana is used for several value added products like handicrafts, paper, particle board and textiles. The currency of Japan ( Yen) is printed on paper produced from banana fibre. It has several other uses like ropes, strings, supports, etc

Relative abundance of crop residues from horticultural crops and its conversion into biofuels make them competitive as gasoline additives. The fruit wastes are rich in sugars and therefore can be used for the production of first generation biofuels, while vegetables are rich in cellulose, hemicellulose, and lignin. This can be exploited for the second generation biofuels by the cost effective saccharification techniques. The mushroom spent logs are better substrates for bio-ethanol production due to the ease in saccharification.

The popularity of treating organic wastes by means of composting has been steadily growing in the last three decades. Unlike other treatment methods of organic wastes, such as land filling, composting is considered as much safer process.

The bio-fuels production respond to the escalating energy crisis and related pollution problems, we urgently need to adopt new energy supply technologies that utilize renewable energy sources in an efficient and environmentally friendly manner. The transformation of different kind of biomasses (municipal and livestock waste, agricultural and forests residues) in different kind of bio-fuels is an important goal of several researches. The physico-chemical properties of the biomass and bio-fuel management are two important points to chose the best process technologies. In this sense the production of bio-ethanol and bio-gas are one of the main process technologies used for fruit and vegetables waste. Fruit are rich in reducing sugars so it will be interesting to produce first-generation bio-ethanol from this matrices.

Vegetable waste is rich in cellulose, hemicellulose and lignin so the production of second-generation bioethanol could be an useful process. Others technologies to reuse fruit and vegetable waste exploit the proprieties of food matrices to integrate human and animal diet. Fruit and vegetables are rich in antioxidants, pectins, fibres, carbohydrates, mineral salts, food flavours, colorants and these substances can be utilized to integrate animal feedstuffs or to increase the quality of food products. Many process technologies are used to utilize fruit and vegetables nutrients: drying, extraction, fermentation, enzymatic degradation  are some treatment examples that can be useful to recycling and upgrading waste of fruit and vegetable market.