The literature review attempts to make some relevant information of fruit processing sector, namely, fruit industry, consumption and trade, fruit processing, type of processes, industry and quality practices in developing countries and quality issues related to fruit processing industry.
CLASSIFICATION OF FRUITS Fruits can be commonly classified according to the growing region as follows: tropical, subtropical and temperate-zone (Kader and Barret, 1996). The quality of fruit is mainly affected on growing region and most significantly the environmental conditions specific to each region. Listed below are the examples of fruit grown in each region.
Major tropical fruits: banana, mango, papaya, pineapple
Minor tropical fruits: cashew apple, durian, guava, longan, lychee, mangosteen, passion fruit, rambutan, tamarind, sapota, carambola
Citrus fruits: orange, lime, lemon, grapefruit, pummelo, tangerine, mandarin
Non-citrus fruits: avocado, pomegranate, cherimoya, fig, kiwifruit, olive
Small fruits and berries: grape (European and American types), strawberry, raspberry, blueberry, blackberry, cranberry
Pome fruits: Asian pear (nashi), European pear, apple, quince
Stone fruits: plum, peach, cherry, apricot, nectarine
Fruits are essential in the human diet. They contain compounds of nutritional importance, including vitamins which are not synthesized by the human body. Fruits serve as a rich source of energy, vitamins, minerals and dietary fibre. The U.S. Department of Agriculture Dietary Guidelines encourages consumers to choose fresh, frozen, dried or canned forms of a variety of colours and kinds of fruits. Fruits can be defined as the reproductive organs arising from the development of floral tissues with or without fertilization.
WORLD PRODUCTION OF TROPICAL FRUITS The availability of detailed information and reliable statistics is very less on tropical fruit production and world trade (Chang, 2007). Therefore, it constitutes a major constraint in the analysis of supply and demand trends of tropical fruits in the world market (Kortbech- Olesen, 1997; Chang, 2007; and FAO, 2008a). Most fruit producing countries do not have proper routinely record or collect data regarding tropical fruits that are basically produced and/or traded in small quantities (Chang, 2007; and FAO, 2008a). Therefore, production and trade data from reporting countries suffer from a lack of uniformity (FAO, 2003).
Data on tropical fruit production, commercial applications and trade are difficult to be estimated when analysing the global reports, an attempt has been made in this dissertation report to analyse the global production, supply and demand trends of tropical fruits in the world market. In fact, the analysis gives much importance on the research study with regard to the development of fruit processing industry in our country to foresee the future of the fruit industry.
According to the research report published by the Philippine Council for Agriculture, Forestry and Natural Resources and Development has stated that worldwide fruit species of tropical and subtropical are estimated to be around 3,000. Moreover, they have revealed that 500 out of total fruit species are found in Asia. In South East Asia around 120 major and 275 minor species of tropical and subtropical fruits and nuts are found. The most interesting part of that publication is that around 200 species of fruits are remained undeveloped and underused.
According to the report published by Food and Agriculture Organization of the United Nations (FAO), the world tropical fruits production reached 96.8 million tonnes in 2000 excluding banana. This production increased approximately 3.6% annually during the period 2000-2007 to reach 123.7 million tonnes in 2007 (FAO, 2008b). Tropical fruits production in 2004 represented 8.1% of the global world production of fresh fruits and vegetables (FAO, 2007). The annual increase of world production of tropical fruits has been estimated to be 1.7% (FAO, 2003; and Chang, 2007). The projected value of world production of tropical fruits is 139.2 million tonnes by 2014. Banana, mango, pineapple, papaya and avocado are the five major tropical fruit varieties produced and constitute the most important tropical fruit species produced worldwide which account for approximately 75% of the global fresh tropical fruit production (Chang, 2007). Asia consists of major producing region followed by Latin America and the Caribbean and Africa. The world production of tropical fruits from these countries is estimated to be 98% (Ramiro, 2000; FAO, 2003; and Centeno 2005).
CONSUMPTION AND TRADE OF TROPICAL FRUITS Approximately, 90% of all tropical fruits produced worldwide are consumed domestically. The remaining 10% of tropical fruits produced is traded as fresh, accounting for 5% or processed tropical fruit products, accounting for 5%. These processed tropical fruit products include dried or dehydrated fruit, frozen fruit, fruit juice, concentrate, pulp and puree which is further referred to as fruit juice and concentrate and canned fruit (Kortbech-Olesen, 1996; FAO, 2003; CBI, 2007a; and Chang, 2007). Although, the proportionally small quantities of tropical fruits traded internationally, the trade value of them is very significant. The total value of trade of fresh and processed tropical fruit products was estimated at 4.0 billion US dollars internationally in 2004 (Chang, 2007). The total international trade value of fresh tropical fruits amount was 4.7 billion US dollars in 2006. Moreover, an additional 1.3 billion US dollars accounted for the processed tropical fruit products. On the other hand, the value of international trade of bananas and plantains reached 5.6 billion US dollars in 2006 (Chang, 2008). Pineapple is the most dominating fruit in international trade in fresh and processed tropical fruits, with a significant growth in volume and value (Chang, 2007, 2008).
Asia is the leading supplier of processed tropical fruit products. According to the trade data, it shows that Latin America and the Caribbean as the major exporters of fresh tropical fruits (Ramiro, 2000). The European Union (EU) is the largest import markets for both fresh and processed tropical fruits making the United States of America (USA) as the second largest. The both import markets are together accounting for approximately 75% of import of tropical fruits in world production (FAO, 2003; and Chang, 2007). The import of fresh fruits in the EU reached 26.4 million tonnes (8.6%) and 21.0 billion Euro (10.7%) for the concerned tropical fruits. Import volume of fresh tropical fruits in the EU can be cascaded as follows: pineapple-56.3%, mango-14.7%, avocado-13.2% and papaya-2.2%. The total is accounting for approximately 86% of all fresh tropical fruits imported in the EU in the year 2007 (Eurostat, 2005, 2006, 2008). The processed fruit products in the EU increased during the period 2003-2007, accounting for 10.5 million tonnes and 10.0 billion Euros in total imports in 2007. Fruit juice and concentrate of about 62.8% accounted for the largest group of processed fruit products in 2007 in terms of volumes and other processed fruit products accounted for: canned of about 24.8%, dried of about 6.8% and frozen of about 5.6% fruit (Eurostat, 2008). From the total import volume of processed tropical fruits in 2003 constituted 15.4% and it increased to 17.1% in 2007.
One of the most internationally traded tropical fruit is banana which accounted for about one-fourth of 70.89 million tons in 2004 production sold overseas. The export of remaining tropical fruits is less than 10% of the total production. As the major exporters of banana, Ecuador, Costarica and the Philippines accounted for 85% of all tropical fruit exports. Volume of export grew up from less than 1% in 2002 to nearly 8% in 2004 (FAOSTAT, 2012). United States is the major market for banana, accounting 26% of world total production in 2004 followed by Germany and Japan.
Mexico, India and Brazil represented the bulk of mango exports. The total volume exported increased in 2004 by a modest 5% in contrast to an enormous increase of 41% in 2003. The total exported amount of mango by Mexico is about 190 kilotons while the Brazil is about 140 kilotons. USA is the major importer of mangoes accounting for 35% while the EU accounting for 20%.
Papaya is major tropical fruit with exports increased by 47% in 2004 compared with the year 2003. The largest exporter of papaya was Mexico accounting for 75 kilotons during the year 2004 followed by Malaysia accounting for 70 kilotons Brazil accounting for 40 kilotons. USA was the major papaya importer that accounted for 50% of the world total papaya production.
Import demand for tropical fruits worldwide for the next decade is expected to increase, thus import volume is also projected to expand. The projected increase in exports of tropical fruits by FAO in 2014 indicates an annual increase in export volume by 1.4% for mango, 1.7% for pineapple, 2% for avocado and 5.6% for papaya while the USA, EU and Japan remain the largest import markets for tropical fruits. (Rita M. Fabro, S
Scanning Electron Microscopy on Silk Mesh Network
SEM of Silk
Scanning electron microscopy was performed on dialyzed complete chain (degummed silk fraction), soluble silk (light chain) and Insoluble silk (heavy chain). On SEM imaging of complete silk mesh network of silk fibers was observed, but, on separation of silk fibers no such fiber network is observed which shows complete separation of light and heavy chains. The white spots present in complete silk are traces of sericin. This is due to the stickiness of the protein material.
Figure. 18 Shows SEM image of different silk (A-C) Complete chain. (D-F) Heavy chains (G-I) Light chain
For functionalization of silk surface by peptides carboxylic groups are required, however, in case of silkworm silk only 1.41% of amino residue contain carboxylic group which make it difficult to functionalize . For, increasing carboxylic functional group on silk surface diazonium coupling was done. In this coupling tyrosine and histidine present in silk fibroin was modified by diazonium salt having carboxylic functionality. This increase number of grafting sites by 6.7% .
Figure 19. UV−vis spectra of light chain silk at different steps of Diazo-coupling. Inset shows Desaltation of Diazo-silk.
Diazotization of silk was followed by UV-vis spectrometer. In UV spectra of unmodified silk a peak at 280 nm was observed, which shows the presence of free tyrosine residue. When diazotization occurs this peaks disappear and a new peak was observed at 340 nm with a shoulder at 390 nm which correspond to azobenzene and its derivatives. The formation of azobenzene occurs by the reaction of phenolic chain of tyrosine with diazonium salt. On desaltation the absorbance value of peak is decreased due to removal of the unbounded diazo compound. Figure. 19 shows modification of tyrosine by diazonium compound.
Figure 20. Modification of Tyrosine in silk by Diazo-coupling.
Figure. 21 ATR-FTIR of Diazo and unmodified Silk
ATR-FTIR of unmodified and diazo modified silk (figure. 21) was done to confirm diazotization of silk. In both the spectra 3 major peaks were observed. A peak occurring at 1650 cm-1 corresponds to Amide I band of proteins . Board peak occurring at 1530 cm-1 depicts Amide II, which is resultant of bending vibrations of N-H and stretching vibration of C-N . This peak also corresponds to β-sheet structure of protein. Another peak was observed at 1240 cm-1 this corresponds to an Amide III band. These bands, mainly arise due to a mixture of coordinate displacement . So these results show that there is no change structure of protein in silk after surface modification of diazo salts. In this study no peaks were observed from the diazonium compound because entire spectra was dominated by the protein backbone of silk .
Figure. 22 Raman Spectroscopy of Diazo and unmodified Silk
Raman spectroscopy of Diazo and unmodified silk is reported in Figure. 22. This was done to determine successful Diazotization silk. Unlike, ATR-FTIR in Raman spectra of Diazo silk a sharp peak corresponding to υ (N=N) aromatic was observed at 1427 cm-1which signifies successful diazotization of silk. The Peak occurring at 1660 cm-1, 1238 cm-1 and 639 cm-1 corresponds to Amide I, Amide III and Amide IV respectively . These three Amides peaks along with peaks at 847 cm-1 (peak from Tyrosine), 2934 cm-1 (C-H) and 565-220 cm-1 (Peaks from backbone deformations) are found in both the silk. Unidentified peak are star marked. All other peaks are explained in the table below [51, 52]:
565- 220 cm-1
Table. 3 Showing all the Peaks in Raman spectra of Diazo and unmodified silk. (Peak marked Red is common in Both the Spectra, Black one is found in Diazo silk only)
Peptide Synthesis and Characterization
All the peptide was synthesized by SSPS method. All these peptides are selected on the basis of their charge at different pH value and binding affinity for HAP system (figure 23). Mass spectroscopy and HPLC were done to determine purity of these peptides. HPLC of CAP(S), Si-4 and Cap (A) peptide shows purity of 90.82%, 80.90% and 96.78% respectively. However, In Case of Cap (H) HPLC no peaks were obtained this because this peptide doesn’t dissolve in the solvent. Cap (H) is 50% hydrophilic and 50% hydrophobic. Different solvent were used for dissolving this peptide but no results were obtained in HPLC until now.
Figure. 23 Graph Showing Charge on the peptide at different pH value.
Mass spec of all the peptides matches well with the monoisotopic mass of peptides.
Peak identified in Mass Spec
Table. 4 Showing peptide mass and obtained mass for MALDI-TOF
X -ray diffraction analysis
XRD of synthesized samples was done to obtain characteristic peak of hydroxyapatite. To determine the phase of calcium phosphate formed in the synthesis.
FTIR of all the samples was performed to determine the formation of Hydroxyapatite (HAP). A standard sample was also run for comparison of results. All samples show the same IR spectrum confirming the formation of HAP. A peak corresponding to hydroxyl stretching was observed from 3200-3500 cm-1 (for clear IR spectra check appendices of chapter 4). Another peak corresponding to hydroxyl group was observed at 1650 cm-1 these two –OH peaks confirm the formation of (HAP). A shoulder peak occurring at 1096 cm-1 corresponds to PO43-. This peak occurs due to v3 bending mode. Peak at 1018 cm-1 corresponds to HPO4 2- present in non-stoichiometric HAP. The Peak occurring at 962 cm-1 depicts non-degenerated symmetric stretching of the P-O bond. Two peaks observed at 602 cm-1 and 561 cm-1 occurs due to triply degenerated bending mode of O-P-O bonds. All these samples match well with standard sample. Thus confirming the formation of HAP. Figure. 25 ATR-FTIR of all HAP samples prepared at different interval of time.
All prepared samples were carbon-coated on aluminium stage. SEM-EDX characterization was done to determine Ca:P ratio in synthesized samples. A standard sample was also setup for comparison of results. Each sample is characterized at five different magnifications and EDX was done on each magnification with elemental mapping. Ca:P ratio on each magnification for all the samples is given below in Table 4. Figure. 26 (I-III) shows SEM images with elemental mapping for all the samples at 5000x. All these results show that formed sample is calcium deficient-HAP i.e. Ca10x (HPO4)x(PO4)6-x(OH)2-x (0 < x < 1) CDHAP has value between 1.5 to 1.67 .