Original scientific paper Izvorni znanstveni članak SUMMARY The primary object of this paper was to investigate the influence of carrot powder (CP) addition to corn grits at levels 4, 6 or 8% and ascorbic acid (AA) addition at levels 0.5 and 1%, on hardness, fracturability, expansion and density of the extrudates. Sensory attributes of the selected extrudates were scored by the panel of ten professional tasters. Extrusion was done at two temperature regimes: 135/170/170°C and 100/150/150°C. Lower temperature regime led to increased hardness and density of extrudates, but at the same time to better expansion. The addition of CP and AA led to decreased hardness and the expansion, but increased density at both temperature regimes. Sensory assessment gave satisfactory results, especially for E1 temperature regime and 4% of carrot powder addition. SAŽETAK Cilj je ovoga rada bio odrediti utjecaj dodatka mrkve u prahu (eng. carrot powder/CP) u udjelima 4, 6 ili 8% i askorbinske kiseline (eng. ascorbic acid/AA) u udjelima 0,5 i 1% u kukuruznu krupicu na tvrdoću, lomljivost, ekspanziju i nasipnu masu ekstrudata. Senzorska svojstva odabranih ekstrudata odredio je panel od 10 senzorskih ocjenjivača. Ekstruzija je provedena pri dva temperaturna režima: 135/170/170°C i 100/150/150°C. Niži temperaturni režim doveo je do povećanja tvrdoće i nasipne mase ekstrudata te, istovremeno, do bolje ekspanzije. Dodatkom CP i AA, smanjila se tvrdoća i ekspanzija, ali se povećala nasipna masa kod oba temperaturna režima. Senzorska je analiza dala zadovoljavajuće rezultate, osobito za E1 temperaturni režim te 4%-tni dodatak mrkve u prahu.

No abstract

High-voltage electrical discharge (HVED) is considered as a novel, non-thermal process and is currently being researched regarding its effect on microorganisms (decontamination of food), waste water treatment, and modification of different compounds and food components. In this paper, four native starches (maize, wheat, potato, and tapioca) were treated with HVED, phosphorylated with Na2HPO4 and Na5P3O10, and modified by a combination of HVED with each phosphorylation reaction both prior and after chemical modification. Pasting properties, swelling power, solubility, gel texture, and particle size were analyzed. Although HVED induced lower contents of P in modified starches, it had an effect on analyzed properties. The results revealed that HVED treatment alone had a limited effect on pasting properties of starches, but it had an effect on properties of phosphorylated starches, both when it was conducted prior and after the chemical modification, reducing the influence of Na5P3O10 and Na2HPO4 on the decrease of pasting temperature. With minor exceptions, the gel strength of starches increased, and the rupture strength decreased by all modifications. HVED treatment resulted in a decrease of the particle size after the modification of maize and wheat starches, while potato and tapioca starches were not significantly influenced by the treatment.

The aim of this research was to explore the use of a high-voltage electrical treatment (HVED) as a substitute for heating during the phosphorylation of maize starch. Starch was treated with HVED, phosphorylated with Na2HPO4 or Na5P3O10 with and without thermal treatment and phosphorylated in combination with HVED prior to and after the chemical modification. When starch was phosphorylated with Na2HPO4, HVED was more efficient in catalyzing reaction (3.89 mg P/kg for 30 min HVED in relation to 0.43 mg P/kg for thermal treatment), whereas with Na5P3O10 similar P content was achieved as with thermal treatment (0.76 P/kg for 30 min HVED in relation to 0.86 mg P/kg). The order of HVED and chemical reactions did not have a marked effect on phosphorous content. In combination with Na2HPO4, HVED pre-treatment had a more pronounced effect on the solubility and water absorption, whereas post-treatment was favoured with Na5P3O10. Mean diameter was increased by all treatments, where HVED had a marked effect. Enthalpy of gelatinization ranged from 11.76 J/g for starch treated with Na5P3O10 and 10 min-HVED to 13.58 J/g for Na5P3O10 treated sample. G′ and G″ increased after both thermally and HVED enhanced phosphorylations, with a slightly more pronounced effect of the HVED.