Radiofrequency heating for powder pasteurization of barley grass: antioxidant substances, sensory quality, microbial load and energy consumption

Abstract

BACKGROUND: Young barley grass powder contains abundant nutrition and its antioxidant substances are severely impaired by radiation ( 60 Co) sterilization. To overcome product quality degradation, radiofrequency pasteurization was conducted using pilot-scale radiofrequency equipment (27 MHz, 6 kW) with electrode gaps of 12, 14 and 16 cm, while hot-air (80 ∘ C) pasteurization was used for comparison. RESULTS: Assessment suggested that uneven radiofrequency heating was improved for the 14 cm electrode gap. With an increase of electrode gap, microbial inactivation needs more energy consumption. A minimum energy consumption of 970 J g −1 was required for 1 log-reduction of colonies. Radiofrequency pasteurization retained better antioxidant substances, lightness (L*), green color (a*) and odors in barley grass powder, compared with hot-air sterilization. Contents of flavonoid and chlorophyll were 5.82 and 4.87 g kg −1 respectively, using the 14 cm electrode gap. Additionally, radiofrequency pasteurization led to an improvement in sourness, bitterness and umami tastes. CONCLUSIONS: Radiofrequency pasteurization would be a superior alternative for the pasteurization of barley grass powder. Temperature and moisture content Five fiber sensors (Nortech Fibronic Inc., Quebec, Canada) were placed in the middle layer of samples. Each process for detecting J Sci Food Agric 2019; 99: 4460-4467

Comparison of hydrability, antioxidants, microstructure, and sensory quality of barley grass powder using ultra‐micro‐crushing combined with hot air and freeze drying

“…However, the fiber degradation in the barley grass destructed numerous fissures and porous structure, and the less fissures and porous structures result in low value of water‐holding capacity and oil‐holding capacity. Other studies found that apple dietary fiber after UMC also appeared a decline in dissolving capacity (Alsuhaibani, 2015; Cao et al., 2018b, 2019). The reason might be different physicochemical properties of barley grass and apple fiber.…”

“…(2018) found that barley grass powder is rich in chlorophyll, protein, vitamins, minerals, and other nutrients. In particular, it is high in antioxidants, chlorophyll, flavonoids, and dietary fiber (Cao et al., 2017, 2019; Mujoriya & Bodla, 2011). Barley grass powder is helpful in controlling some diseases, such as diabetes and rheumatic disease (Rana et al., 2011).…”

Effect of Intermittent Microwave Volumetric Heating on Dehydration, Energy Consumption, Antioxidant Substances, and Sensory Qualities of Litchi Fruit during Vacuum Drying

“…The decomposition could be due to higher oxidation in MVD. Higher temperature causes mass oxidation and decomposition to form charring substances [11,12].…”

“…MVD led to browning and increased bitterness, which lowered the evaluation scores. The main reason might be non-enzymatic oxidation resulting in darkness and bitterness [12,26]. This means that MVD leads to charring causing bitterness and forms sweet substances by high volume heat.…”

“…On the other hand, microwave-assisted drying contributes to reducing time and cost; however, it may devaluate products in case of non-uniform heat, impairing product quality [5,11]. On the other hand, microwave vacuum drying allows balancing dehydration rate and product quality between vacuum-drying and microwave-drying [5,12]. Some researchers have evaluated the effect of microwave vacuum drying on the texture of pumpkin slices and found suitable to produce dried-and-crisp pumpkins [13,14].…”