Influence of hydroxypropylation on retrogradation properties of native,defatted and heat-moisture treated potato starches |
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| Affiliation: | 1. College of Food Science, Sichuan Agricultural University, Ya''an 625014, China;2. College of Mechanical and Electrical Engineering, Sichuan Agricultural University, Ya''an 625014, China;3. Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, USA;1. School of Bioengineering and Food Technology, Shoolini University of Biotechnology and Management Sciences, Bajhol, PO Sultanpur, Distt. Solan-173229 (HP), India;2. Department of Food Science and Technology, Chaudhary Devi Lal University, Sirsa, Haryana, India;1. Department of Food Science and Technology, Pondicherry University, Puducherry 605014, India;2. School of Industrial Fisheries, Cochin University of Science and Technology, Kochi 682016, India;3. Department of Fish Processing Technology, Kerala University of Fisheries and Ocean Studies, Kochi 682506, India;4. Department of Food Science and Technology, Government College for Women, MA Road, Srinagar, Jammu and Kashmir, India;5. Food Engineering and Packaging Division, Defence Food Research Laboratory, Mysore 570011, India |
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| Abstract: | Recent studies have shown that defatting and heat-moisture treatment cause structural changes within the amorphous and crystalline regions of potato starch. Furthermore, the alkaline reagents (NaOH and Na2SO4) used during hydroxypropylation has been shown to cause structural changes within the amorphous and crystalline regions of native, defatted and heat-moisture treated starches. In this study, we have compared (using different techniques) the retrogradation properties of potato starch before and after physical (defatting and heat-moisture treatment), and chemical (alkaline treatment and hydroxypropylation) modification. Turbidity measurements showed that changes in turbidity during storage (4°C for 24 h and then at 40°C for 29 days) of native, defatted and heat-moisture treated gelatinized starch pastes were influenced by the interplay of two factors: (1) interaction between leached starch components (amylose–amylose, amylose–amylopectin, amylose–amylopectin), and (2) interaction between granule remnants and leached amylose and amylopectin. In alkali treated gelatinized native, defatted and heat-moisture treated starch pastes, turbidity changes on storage was influenced by aggregation of granule remnants. Hydroxypropylation decreased the rate and extent of increase in turbidity during storage of native, defatted and heat-moisture treated starches. The change in turbidity during storage of hydroxypropylated starch pastes was influenced by the interplay between: (1) steric effects imposed by hydroxypropyl groups on chain aggregation, (2) aggregation between small granule remnants, and (3) settling of large granule remnants beneath the path of the spectrophotometer beam. Stored gelatinized pastes of native, defatted and heat-moisture treated starches gave a `B' type X-ray pattern. A similar pattern was also observed after alkaline treatment, and hydroxypropylation. However, the X-ray intensity of the strong reflection at 5.2 Å decreased after alkaline treatment and hydroxypropylation. The retrogradation endotherm (monitored by differential scanning calorimetry) occurred after 2 days storage in native, defatted and heat-moisture treated starches. A similar trend was also observed after alkaline treatment. However, the retrogradation endotherm appeared only after 7 days in hydroxypropylated starches. The enthalpy of retrogradation in all starches decreased on alkaline treatment and hydroxypropylation. |
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