Co-applying biochar and manganese ore can improve the formation and stability of humic acid during co-composting of sewage sludge and corn straw.

This study examined the effects of corn straw biochar (CSB) and manganese ore (MO) on the abiotic formation and stability of humic acid (HA) during sewage sludge composting. Co-applying CSB and MO (106%) induced a higher increase in HA content of final compost product than those of no or single applications (32.6-85.1%). This positive change was achieved by promoting the conversion of humus precursors and fulvic acid to HA through abiotic pathway, respectively, in the early and later stages of composting. The co-application of CSB and MO also exhibited a higher capacity to improve HA stability than those of single applications. In sum, this study confirmed a clear synergistic effect of CSB and MO on improving the formation and stability of HA in compost product, which could further enhance the multi-benefits (e.g., carbon sequestration and soil quality improvement) of compost soil application.

Radio frequency heating of green peas (Pisum sativum L.): The improvement of heating uniformity and its dry blanching effect.

A radio frequency (RF) heating system was used to process green peas and a rotating system was introduced to improve heating rate and heating uniformity. Results revealed that rotation treatment accelerated heating rate effectively and improved heating uniformity index significantly (p < 0.05) from 0.175 (0 rpm, 55°C) to 0.029 (60 rpm, 55°C). After being treated with RF and traditional hot water blanching at 85°C, the residual lipoxygenase activities of green peas were 1.90 ± 0.71% and 35.51 ± 5.25%, respectively, confirming RF possessed better blanching efficiency. Meanwhile, weight loss, electrolyte leakage rate, color, and texture of green peas all had significant changes (p < 0.05) through RF heating. PRACTICAL APPLICATION: A rotation device can effectively improve heating uniformity of RF electromagnetic heating. The rotation device could be expanded or further developed into continuous feeding conveying device for industrial production.

Blanching effects of radio frequency heating on enzyme inactivation, physiochemical properties of green peas (Pisum sativum L.) and the underlying mechanism in relation to cellular microstructure.

Fresh green peas require blanching to terminate enzymatic reaction induced quality deterioration before frozen storage. Radio frequency (RF) heating is a novel way of dry blanching for fruits and vegetables with high processing efficiency. In this study, blanching effects of RF heating on relative activities of lipoxygenase (LOX) and peroxidase (POD), physiochemical properties as well as cellular morphology changes of green peas were investigated. Results showed relative activities of pea LOX and POD reduced to 0.90 ± 0.78% and 1.10 ± 0.71%, respectively at 85 °C by RF heating with an electrode gap 105 mm. Weight loss, color, texture and electrolyte leakage of peas changed significantly with increasing temperature (60-85 °C). Ascorbic acid, chlorophyll and mineral contents had different loss after RF processing and long term heating at 115 mm exacerbated the loss of nutrients. Microstructure features showed the deconstruction of pea cell well and starch granule gelatinization.