**6.3 Proteomics**

Proteins plays an important role in various plant processes including development, growth, ripening and senescence, metabolic functions, resistance to abiotic and biotic stresses. Proteomics and omics approaches has been studied over past few decades and opens a new avenue in understanding ripening and senescence, development, postharvest responses of perishable commodities in many crops like apple, banana, citrus, grapes, strawberry, tomato, peach, papaya, mango etc. They also are crucial in understanding plant mechanisms during pathogen infection as well. Study on proteomics reveals that proteins involved in defense mechanism, energy metabolism and antioxidant system are crucial for food produce in stored condition and elicitor responses [49]. The study of proteomics in postharvest science involves 2-D electrophoresis (classical and/or differential electrophoresis, DIGE) for separating and quantifying proteins based on LC-MS/MS technique either by cross species identification or by species-specific database search. Several postharvest studies and researches also include gel based approach for quantification and identification of proteins. Furthermore, the proteomic research in fruits and vegetables are needed to be extended to other quantitative proteomic approaches like iTRAQ, TMT, peptides demethylation labeling, ICAT, MRM, label-free strategies or the integration of above mentioned approaches with LC–MS/MS. Abdi *et al.,* 2002 [50] studied the postharvest proteomics based on 2D- PAGE related to optimal harvest of peaches. Postharvest proteomics are essential for minimizing postharvest losses by selection of desired quality of cultivars with desired quality of traits. Selection of traits like low susceptibility to bruising and chilling injury to post harvest food products are decisive factors for modulating shelf life of processed products. The combination of transcriptomics, metabolomics and proteomics has been used to study the quality of citrus in storage. Chilling injury is detrimental to produce in storage as

it not only affects degradation of proteins, polysaccharides but also affect organic acids and causes injury to postharvest produce (**Figure 11**).

**Figure 11.**

*(a) Gel based approach and (b) gel free approach. Source: Pedreschi et al., 2013 [51].*
