Preliminary Characterization of Uapaca kirkiana Fruit Pomace: Nutritional, Phytochemical, Functional, and Aroma Profiling as a Potential Feed Ingredient

Abstract

Large-scale and small-scale fruit processing generates large amounts of fruit pomace, which is rich in bioactive compounds and offers an eco-friendly opportunity for valorization as a livestock feed ingredient. This study aimed to preliminarily characterize the nutritional, phytochemical, functional, and aroma properties of Uapaca kirkiana pomace powder. Chemical composition was determined by standard proximate methods, phytochemical profiling by gas chromatography-mass spectrometry (GC-MS), functional properties by gravimetric tests, and aroma by olfactory analysis. The pomace had an acidic pH (4.36 ± 0.02) and a low moisture content (8.74 ± 1.12%). Proximate composition was as follows: crude protein 13.62 ± 0.58%, crude fibre 21.65 ± 1.39%, crude fat 4.40 ± 0.17%, and nitrogen-free extract 46.56 ± 0.43%. Neutral detergent fibre and acid detergent fibre were 47.17 ± 1.02% and 32.77 ± 1.12%, respectively. The calcium-to-phosphorus ratio was 3.7:1, while the tannin content was negligible (0.453 ± 0.14 mg/100 g DM). The bulk and tapped densities were 0.46 ± 0.01 and 0.57 ± 0.01 g/ml, respectively, yielding a Carr index of 19.3%, indicating good flowability. The GC-MS revealed a complex phytochemical profile dominated by linoleic (22.09%), palmitic (16.77%), and stearic (3.58%) acids. The pomace had a mild, fruity aroma with no off-notes. These preliminary findings indicate that U. kirkiana pomace possesses attributes warranting further investigation as a potential feed ingredient. However, as the study was conducted on a single batch without in vivo feeding trials or safety evaluations, all inferences remain hypothesis-generating and require empirical validation before practical recommendations can be advanced.