Heat treatment of apple (Malus domestica Borkh.) pomace with different oven temperatures does not enhance its nutritive value

ABSTRACT

The study evaluated the effect of heat-treating apple (Malus domestica Borkh.) pomace with different oven temperatures on chemical composition and in vitro ruminal fermentation with or without polyethylene glycol (PEG). Eight replicate samples of air-dried fresh apple pomace (CON) were each oven-dried for 30 min at 60°C (T60), 80°C (T80), 100°C (T100), 120°C (T120), and 130°C (T130). Heat treatment increased (P < 0.05) dry matter, organic matter, neutral detergent fibre and acid detergent fibre of the pomace. The untreated pomace (CON) had the highest crude protein content (94.0 g/kg DM) while the lowest was from T180 (49.84 g/kg DM). The inoculation with PEG had higher cumulative gas production than the one without PEG. Similarly, PEG inoculation increased (P < 0.05) the rate of gas production from fraction b (c), effective gas production, and partitioning factors. It was concluded that heat treatment does not improve the nutritive value of apple pomace.

KEYWORDS:

• Agro-wastes
• Chemical composition
• Heat treatment
• Rumen fermentation
• Ruminants

Acknowledgement

We are grateful to Eligin Fruit Juice (Pty) Ltd for the provision of the apple pomace used in this study.

Disclosure statement

No potential conflict of interest was reported by the author(s).