Effect of basil leaves and wheat bran water extracts on enzymatic browning of shredded storage iceberg lettuce

Abstract

Summary The impact of functional solutions (water infusions of radish sprouts, wheat bran (WBE), basil leaves (BLE) and lentil protein hydrolysate) on enzymatic browning of shredded iceberg lettuce was studied. BLE and WBE, limiting enzymatic browning in the highest degree, were tested during cold storage. The best inhibitors of PPO activity in lettuce stored for 8 days were 10% WBE (a decrease by 97%). POD activity was substantially decreased by ascorbic acid (by 75%) and 1% BLE (by 83%). POD and PPO inhibition was reflected in a decrease in enzymatic browning, that is 91% and 88% reduction was found in 8‐day stored lettuce treated with 1% BLE and 1% WBE, respectively. In the case of POD, mixed inhibition was recorded for BLE and WBE, while these solutions acted as competitive inhibitors of PPO activity. The enzymatic browning of shredded iceberg lettuce during cold storage may be effectively suppressed by natural extracts.

Effect of Basil Leaves and Wheat Bran Water Extracts on Antioxidant Capacity, Sensory Properties and Microbiological Quality of Shredded Iceberg Lettuce during Storage

“…In contrast, Altunkaya & Gökmen [33] observed an opposite relationship during storage of fresh lettuce (Lactuca sativa). What is important, the increase in the phenolic content in the lettuce treated with the basil leaf extracts in the present study may also be explained by the fact that the extracts are rich in phenolics, mainly rosmarinic acid and quercetin derivates [9]. Llorach, Martinez-Sánchez, Tomás-Barberán, Gil, & Ferreres [34] reported that the antioxidant activity (DPPH or FRAP) of lettuce was highly correlated with the total phenolic content.…”

“…For preparation of the infusions, 10g of dried samples was mixed with 100 mL of boiling water and left to cool down. Then, the samples were centrifuged (15,000× g, 25 • C for 15 min), collected, diluted to working concentrations with water and used for the treatments [9].…”

“…Then, an excess of the solution was removed. After that, the lettuce was kept in polypropylene boxes at 4 • C for 8 days [9]. The samples were collected for the tests at storage days 3, 5, and 8, rapidly frozen, lyophilized, and kept in polyethylene bags at −20 • C or used immediately for microbiological and consumer quality tests.…”

“…In our previous study, we have proved that enzymatic browning of shredded iceberg lettuce during cold storage can be effectively limited by application of water infusions of wheat bran and basil leaves. After 8 days of storage, a 91% and 88% reduction of the browning index was recorded after application of 1% basil leaf and 1% wheat bran extracts, respectively [9]. Furthermore, the functional solutions exhibited a mixed mode of POD inhibition and acted as competitive inhibitors of PPO activity.…”

“…However, a significant amounts of quercetin glucosides were also detected. The wheat bran extract contained only apigenin derivates (with a dominant apigenin-hexoside-pentoside) without any phenolics acid e.g., ferulic acid [9]. Most importantly, the functional solutions were standardized in terms of phenolics compounds (responsible for inhibitory effect [4]), thus other parts of plants (e.g., stems being waste material) or other sources may be used to reduce the costs.…”