Lactulose production from milk concentration permeate using calcium carbonate-based catalysts

Milk concentration permeate (MCP), a low-value by-product of ultrafiltration plants and calcium carbonate-based catalysts were used for lactulose production. The results obtained show the effectiveness of oyster shell powder and limestone for lactose isomerisation as a replacement for egg shell powder. With the reaction conditions of 12 mg/ml catalyst loading, reflux time of 120 min at 96 °C, a maximum yield of 18–21% lactulose was achievable at a cost of <50% of original lactose degradation (measured by HPLC). De-proteination of MCP by acidification prior to isomerisation helped lactulose formation in the earlier stages, but did not significantly increase the yield. The resulting lactulose MCP (40 °B) incorporated at the rate of 3–4% was effective in enhancing the growth rate and acid production of Lactobacillus acidophilus (LA-5) in probiotic products.     

Process optimisation for fractionating Jerusalem artichoke fructans with ethanol using response surface methodology

Optimal conditions for fructan precipitation from Jerusalem artichoke concentrate by adding ethanol were established by response surface methodology. The combination of the starting syrup concentration (9.9–40 °B), ethanol-to-syrup (E/S) ratio (2.3:1–15.7:1) and precipitation temperature (3.1–62 °C) was varied at design points of a central composite rotatable design. Significant regression models describing the changes of average chain length, fructan precipitation yield and purity value of fructans were developed with the coefficient of determination greater than 0.8. The results suggested that higher syrup concentration resulted in an increased fructan yield, but further increase in concentration had a reverse effect on average chain length and purity values. The optimum conditions for fractionating fructan composition by ethanol were estimated to be 32 °B initial syrup concentration, E/S ratio of 13 and temperature of 42 °C.     

Probiotic stability of yoghurts containing Jerusalem artichoke inulins during refrigerated storage

Experimentally prepared Jerusalem artichoke inulins (JAI) were compared with two commercial chicory root inulins for their prebiotic potentials in media broth model and growth-sustaining ability in non-fat yoghurts. Experimental yoghurts were made with 12% reconstituted skim milk (RSM) supplemented with 4% inulin powders, inoculated with mixed cultures of Lactobacillus casei LC-01, Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (1:0.5:0.5 based on supplier’s recommendation) and incubated overnight at 37 °C. Non-supplemented yoghurt was prepared from 16% RSM and used as control. The survival and acidifying activity of lactic and probiotic cultures in all yoghurts were investigated on weekly intervals during the shelf life of 28 days at 4 °C. Incorporation of JAI resulted in improved viability of LC-01, maintaining >7.0 log CFU/g during cold storage but did not affect the viability of yoghurt bacteria in comparison with the control.