DEVELOPMENT AND EVALUATION OF LACTOSE HYDROLYSED SKIMMED MILK POWDER WITH REDUCED MAILLARD BROWNING
| dc.contributor.advisor | ARORA SUMIT | |
| dc.contributor.author | PAYAL SINGH | |
| dc.date.accessioned | 2024-08-08T09:11:17Z | |
| dc.date.available | 2024-08-08T09:11:17Z | |
| dc.date.issued | 2022 | |
| dc.description.abstract | Lactose hydrolysed milk powder (LHMP) with reduced Maillard browning and improved techno-functional properties was prepared. The source of β-galactosidase (K. lactis and B. lichenformis) was selected on the basis of their maximum hydrolytic and trasgalactosylation activity in a model system. β-galactosidase from K. lactis was more effective than B. lichenformis for hydrolysis of lactose (DH) and galactooligosaccharide (GOS) formation in model system (16 % lactose). Hence, β-galactosidase from K. lactis was utilised (2.50, 4.80, 7.14 and 9.53 U/mL) for hydrolysing concentrated skim milk (35-40 % total solids). DH and GOS formation were evaluated at different time intervals (0-24 h). The use of 9.53 U/mL enzyme resulted in significantly high DH (100 %) after 12 h with 9.45 % IL (initial lactose) GOS formation. Multi-enzyme approach was also followed besides a single enzyme for preparing lactose hydrolysed/free milk. Glucose oxidase (GOX) was used to oxidise the monosaccharide (glucose) produced during lactose hydrolysis in milk. The activity of GOX with and without catalase (CAT) was also evaluated for maximising its activity. The time interval at which GOX+CAT should be added after the β-galactosidase action in milk was also standardised. Further, the optimised concentration of GOX (G1, G2, G3 and G4 U/mL) incorporated alongwith CAT (C1 U/mL) resulted in a significant (p<0.05) reduction of glucose (~50 %) after t11 h of reaction with minimum changes in pH of milk. The multi enzyme-based lactose hydrolysed milk was then spray dried for the preparation of powder (P3) by optimising inlet air temperature (T1, T2 and T3 ºC) at feed flow rate of F mL/min based on physical and Maillard browning characteristics (moisture, water activity, solubility, colour, hydroxylmethylfurfural (HMF), available lysine and furosine). Powders P1 i.e. skim milk powder (SMP) and P2 (single enzyme-based LHMP) were also prepared using the optimised conditions. Among the different inlet air temperatures, P3 prepared at T2 °C resulted in lower moisture content, water activity and Maillard reaction indicators (HMF, furosine and browning index), whereas, higher solubility and available lysine content was observed. Powder P3 prepared under optimised conditions was further evaluated for compositional and techno-functional properties i.e., lactose (0.20 %), glucose (10.11 %), galactose (21.48 %), GOS (7.89 % IL), fat (1.48 %), protein (34.02 %), ash (7.43 %) and moisture (4.83 %). Loose bulk density, tapped bulk density, flowability, wettability and dispersibility were 0.45 g/mL, 0.55 g/mL, 36.20º, 11.07 s and 88.62 %, respectively. Powder P3 was comparable to P1 with respect to all the parameters evaluated including sensory properties and was superior in quality to the powder P2. Osmolality of reconstituted milk powders P2 and P3 was significantly higher (p<0.05) than powder P1 but were below the maximum limit. Powder P1, P2 and P3 were packed in aluminium laminate pouches and evaluated for physico-chemical changes during storage at 30 °C for 6 months. A significant increase (p<0.05) was observed in moisture content, water activity, HMF, browning index, furosine and titratable acidity, whereas, available lysine and solubility decreased on 6 months of storage for all the powders. Bulk density, tapped density, wettability, dispersibility and flowability of powders P2 and P3 changed significantly (p<0.05) upon 6 months of storage, whereas, for P1 a non-significant (p>0.05) change was observed. Significant decrease (p<0.05) in overall acceptability of powders P2 and P3 was evident after storage for 6 and 3 months, respectively, however, P1 reflected non-significant decrease (p>0.05) on storage. No change in crystallisation behaviour of powder P1 and P3 was observed upon storage. However, storage of powder P2 for 6 months led to change in its crystallisation behaviour. Glass transition temperature of milk powders P1, P2 and P3 decreased upon storage for 6 months. In vitro digestibility of proteins and available lysine of powders P1 and P3 were comparable, whereas, the digestibility values of powder P2 was comparatively lower. The present research was successful in overcoming the limitations of LHMP prepared using single enzyme approach with the use of multi enzyme-based approach which minimised the rate of Maillard related undesirable changes during processing and storage. | |
| dc.identifier.uri | https://krishikosh.egranth.ac.in/handle/1/5810213052 | |
| dc.language.iso | English | |
| dc.pages | 189 p. | |
| dc.publisher | ICAR-NDRI, KARNAL | |
| dc.sub | Food Technology | |
| dc.theme | FOOD SAFETY AND QUALITY ASSURANCE | |
| dc.these.type | Ph.D | |
| dc.title | DEVELOPMENT AND EVALUATION OF LACTOSE HYDROLYSED SKIMMED MILK POWDER WITH REDUCED MAILLARD BROWNING | |
| dc.type | Thesis |