ABSTRACT
Pectin is one of the main structural components of plant cell walls. Pectin forms gels under certain circumstances, the gelling mechanism is highly dependent on the degree of methoxylation (DM). Pectin conventionally is divided into high methoxy (HM) pectin with DM>50% and low methoxy (LM) pectin with DM<50%. HM pectin forms gels in the presence of high sugar concentration, usually sucrose or fructose and low pH. Conversely, LM pectin forms gels by interaction of carboxyl group ionized and divalent ions by the “egg box” mechanism. The viscoelastic properties of pectin are the base of its broad use as gelling agent and stabilizer in food products. Although most plant tissues contain pectin, citrus peel, and apple are the major sources of pectic substances around the world. Although most chickpeas are produced for human consumption, low quality grains provide the livestock industry with an alternative protein and energy feedstuff. A large amount of by-products is produced during chickpea processing in regions where this is a major food legume. The majority of chickpea processing wastes include chickpea husk, which is used for animal nutrition. In this chapter, chickpea husk pectin extraction, composition, and functional properties were investigated. Pectin presented a 67% (w/w) of galacturonic acid, an intrinsic viscosity of 374 ml/g and a viscosimetric molecular weight of 110 kDa. Fourier transform infrared (FTIR) spectroscopy spectrum of pectin indicates a degree of esterification of 10%. For 2% (w/v) calcium induced pectin gels, the values of the storage (G¢) and loss (G¢¢) modulus and the gel set time (tg) were 57 and 10 Pa, and 3.5 min, respectively. After 48 hr storage at 25°C, pectin gels showed no significant difference on the texture profile analysis, except for hardness (21% loss). Pectin whippability, foam stability, emulsion stability, and reduced viscosity were maximum at pH 9 (124, 95, and 96% and 61 ml/g, respectively). The results attained suggest the use of this pectin as potential texturing agent for the food industry.
