Nutritional and phytochemical enrichment of pineapple peel using Aspergillus niger through solid-state fermentation

Abstract

Importance of the work: Aspergillus niger fermentation improves the nutritional and
phytochemical value of underutilized pineapple peel (PP), highlighting its potential as an
animal feed or additive.
Objectives: To evaluate the nutritional and phytochemical composition of PP fermented by
A. niger using solid-state fermentation (SSF).
Materials and Methods: The PP was dried, supplemented with ammonium sulfate, sterilized,
inoculated with A. niger strain ANL-AN01 and fermented for 120 hr. After fermentation,
samples were analyzed for proximate composition, amino acid profile, total phenolic content
and total antioxidant capacity.
Results: SSF of the PP using A. niger significantly (p < 0.01) reduced dry matter by 29.74%
and nitrogen-free extract by 25.12%, while crude protein increased by 263.12%, crude fiber
by 37.93% and ash by 38.73%, whereas crude fat remained unaffected (p ≥ 0.05). The total
phenolic content decreased by 19.47% (p < 0.01), whereas the total antioxidant capacity
improved markedly by 119.44% (p < 0.01). Amino acid profiles were significantly (p < 0.01)
enhanced, except for lysine and methionine (p < 0.05). Total amino acids, total essential
amino acids and total non-essential amino acids increased by 102.85%, 68.69% and 124.88%,
respectively. Glutamic acid, arginine and aspartic acid had the highest improvements among
the individual amino acids.
Main finding: A. niger fermentation significantly enhanced the contents of protein and amino
acids, as well as the antioxidant capacity of PP, demonstrating its novel potential as a nutrientenriched animal feed and sustainable utilization strategy for agro-industrial byproducts.