Developing Radio-Frequency Roasting Protocols for Almonds Based on Quality Evaluations.

Area of Science:

• Food Science and Technology
• Agricultural Engineering

Background:

• Conventional hot air roasting of almonds is time-consuming.
• Dielectric heating offers a potential alternative for faster food processing.

Purpose of the Study:

• To evaluate the efficacy of radio-frequency (RF) dielectric heating for almond roasting.
• To compare the quality and sensory attributes of RF-roasted almonds with conventionally roasted almonds.

Main Methods:

• Almonds were roasted using a 5 kW, 40.68 MHz batch RF equipment at varying weights and times to reach 120 °C.
• Quality attributes (color, moisture, acid value) and aroma profiles (GC-IMS) were analyzed.
• Sensory evaluation and comparison with conventionally oven-roasted almonds were conducted.

Main Results:

• RF heating significantly reduced roasting time compared to conventional methods (minutes vs. hours).
• RF-roasted almonds exhibited desirable darker color, lower moisture content, and reduced acid value, indicating better preservation potential.
• Gas chromatography-ion mobility spectroscopy (GC-IMS) and principal component analysis (PCA) showed RF roasting produced a richer aroma profile similar to commercial products.
• Sensory evaluation favored RF-roasted almonds for flavor, texture, and overall preference.

Conclusions:

• Radio-frequency dielectric heating is an efficient and effective method for roasting almonds.
• RF roasting enhances almond quality attributes and sensory characteristics, offering a viable alternative for industrial applications.