Bioactivity and volatile compound evaluation in sheep milk processed by ohmic heating.

Area of Science:

• Food Science and Technology
• Biochemistry
• Dairy Processing

Background:

• Conventional heating (CH) methods can impact the quality and functional properties of sheep milk.
• Ohmic heating (OH) is an alternative processing technology with potential benefits for food safety and bioactive compound preservation.
• Sheep milk contains valuable bioactive peptides and volatile compounds that can be affected by processing and storage.

Purpose of the Study:

• To compare the effects of ohmic heating (OH) and conventional heating (CH) on functional compounds in raw and thawed sheep milk.
• To assess the impact of OH and CH on bioactive peptides, enzyme inhibition (antihypertensive, antidiabetic), and antioxidant activity.
• To evaluate the preservation of volatile compounds in sheep milk after OH and CH processing.

Main Methods:

• Sheep milk samples (fresh and frozen up to 3 months) were subjected to different OH conditions (3.33–8.33 V/cm) and compared to CH (73°C/15 s).
• Functional properties including angiotensin-converting enzyme inhibition, α-amylase and α-glucosidase inhibition, and antioxidant activity were measured.
• MALDI-TOF mass spectrometry was used to identify bioactive peptides, and gas chromatography-mass spectrometry (GC-MS) was employed for volatile compound analysis.

Main Results:

• OH processing resulted in higher levels of bioactive peptides and enhanced functional activities (antioxidant, antihypertensive, antidiabetic) compared to CH and raw milk.
• Antioxidant activity ranged from 0.11% to 0.71%, antihypertensive activity from 0.20% to 0.72%, and antidiabetic activity from 0.21% to 0.79% in OH-treated samples.
• OH processing preserved volatile compounds better than CH, with some degradation observed due to freezing, storage, and heating.

Conclusions:

• Ohmic heating is a superior method for processing sheep milk, improving its bioactive peptide profile and functional health benefits.
• OH processing effectively preserves volatile compounds, contributing to the overall quality and sensory attributes of sheep milk.
• This study demonstrates the novel application of ohmic heating for enhancing sheep milk quality and safety.