The effect of utilisation of citrus pomace dried with different methods on dairy goats' milk yield, quality and organoleptic properties of dairy products

In the two-stage current study it was aimed to determine the best drying method and the potential of the dried pulp substitution with corn in concentrate feed. On the first trial; nutrient and in vitro digestibility analyzes were carried out by drying citrus (orange, grapefruit and lemon) pomaces with different methods (hot air, infrared energy, hot air + infrared energy; 70 oC and 80 oC) in 3x3x2 18 treatment groups. The grapefruit pomace dried with hot air + infrared energy, resulted the best in vitro digestion. Drying methods affected the Mg and Fe levels and the total ester content of aroma substances in pomaces. Fatty acids were also significantly (P<0.05) affected by drying methods. In vitro digestibility analysis found that the best material was grapefruit pomace dried with hot air + infrared energy. However, due to the bitter taste of grapefruit and the inability to produce the industrial hot air+ infrared energy drying machine, orange pomace dried with 80 oC hot air was used in the second stage of the study. In the rations of dairy goats, dried pomace was replaced with corn at different levels (7.5%, 15 and 22.5 DM). The treatments increased the dry matter consumption of the goats, did not affect the milk yield and the efficiency of converting the feed into milk, but affected the live weight changes negative. Milk dry matter was partially affected negative by pomace replacement at 2nd and 3th weeks, and improved with increased pomace use at 6th and 7th weeks. While the effects of the treatments on milk protein and casein levels were insignificant (P>0.05), except for the 3rd week; an increase was observed in milk fat at 6th, 7th and 8th weeks, and lactose level increased at 3th, 4th and 5th weeks. Treatments negatively affected blood glucose, cholesterol, NEFA, BHB, IGF-1, milk fatty acid, and affected positive the aroma, Cu, Fe amount of milk and cheese yield. In the middle of the study, somatic cell count was found to be lower in the control group and no effect was observed on the quality or organoleptic properties of cheese and ice cream. Keywords: Aroma, Citrus, Organoleptic, Pomace, Milk.