Enhancement of the nutritional and bioactive properties of oil palm pollen through solid-state fermentation with <i>Lactobacillus rhamnosus</i>

Oil palm plantations generate large quantities of pollen that remain underutilized despite its potential as a nutritional resource for honeybees. However, the relatively low protein content of palm pollen limits its direct use in bee feed formulations. This study aimed to enhance the nutritional and bioactive properties of palm pollen through solid-state fermentation using Lactobacillus rhamnosus. The experimental design consisted of four treatments: T1 (Ceiba pentandra Gaertn. pollen as control), T2 (raw palm pollen), T3 (palm pollen mixed with honey), and T4 (palm pollen fermented with L. rhamnosus and honey). Nutritional composition, vitamin content, amino acid profile, mineral concentration, bioactive compounds, and antioxidant activity were analyzed using One-Way Analysis of Variance (ANOVA). Normality and homogeneity were evaluated using the Shapiro-Wilk and Levene’s tests, respectively, followed by Duncan’s Multiple Range Test for significant differences (p < 0.01). Fermented palm pollen (T4) showed the highest crude protein (26.83%), carbohydrate (60.48%), retinol (0.094 mg/100 g), ascorbic acid (1.13 mg/100 g), and tocopherol (1.60 mg/100 g), together with increased essential amino acids, minerals (Ca, P, Mg, and Fe), total phenolics (185.41 mg GAE/g), flavonoids (96.88 mg QE/g), and antioxidant capacity measured using DPPH radical scavenging, ABTS radical cation scavenging, and FRAP reducing power assays. In contrast, crude fat and fiber contents decreased following fermentation. These results demonstrate that fermentation with L. rhamnosus improves the nutritional and functional properties of palm pollen, although further in vivo studies are needed to confirm its effects on honeybee health and colony performance.