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The aim of this research was to investigate the influence of the addition of tomato powder (TP) to corn grits at levels 4, 6 or 8 % and the addition of ascorbic acid (AA) at levels 0.5 and 1 %, on total polyphenol content (PF), and antioxidant activity of the extrudates. The hardness and the expansion ratio of the extruded products were also tested. Mathematical models that describe the influence of additives on the mentioned properties were also determined. Extrusion was performed at two temperature regimes: 135/170/170 °C and 100/150/150 °C. Lower temperature regime led to increased hardness and the expansion of extrudates. The addition of tomato and AA led to decreased hardness and the expansion at both temperature regimes. The addition of tomato increased PF and AA compared with pure corn extrudates. Greater degradation of PF and AA was at lower temperature regime. High correlation between PF and AA was demonstrated at both extrusion temperatures.

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.

As a by-product of the winemaking process, grape seeds have been receiving increased attention worldwide due to a number of beneficial nutritional properties. Moreover, grape seed oil has also been gaining prominence for its high content of unsaturated fatty acids, primarily linoleic acid (C18:2) (72-76%). The objective of this paper was to determine the influence of three different grape seed drying temperatures (20, 40 and 60 °C) on the quality of cold-pressed oils from five different grape varieties (Pinot noir, Pinot blanc, Muscat, Cabernet sauvignon and Graševina). The oils extracted were tested for the acid number (as an indicator of hydrolysis), the percentage of free fatty acids and the peroxide value (as an indicator of autoxidation). The peroxide values of the oil samples considered increased with the increasing drying temperature of grape seeds. The highest peroxide value was observed in the oil samples produced from the Graševina seeds (regardless of the grape seed drying temperature), whereas the Muscat oil samples exhibited the lowest peroxide values. The acid number and the percentage of free fatty acids of the oil samples considered were found to be variety specific and independent of the grape seed drying temperature.

The objective of this research was to investigate the potentiality of carrot powder (CP) utilization at levels 4, 6, or 8% as ingredient of corn snacks and evaluation of the extrusion influence on functionally important ingredients such as carotenoids (color), polyphenols, fiber, fat, and antioxidant activity. The influence of ascorbic acid (AA) as an external source at levels 0.5 and 1% on this particular extrusion was also investigated. A single-screw extruder at two temperature regimes (135/170/170 °C (E1) and 100/150/150 °C (E2)) carried out extrusion. The E1 temperature regime acted favorably on total polyphenol content and crude fiber, but fat preferred the E2 regime. Extrusion, especially the E1 temperature regime, increased the extractability of carotenoids. Ascorbic acid degraded during extrusion, but it still provided protection to carotenoids and color attributes of extrudates. Snacks with increased nutritional and functional value due to carrot powder addition were successfully produced, which is a starting point for production of a new type of extruded snacks.