Combined effects of pulsed electric field and soursop leaf extract treatment and modified atmosphere packaging on melanosis inhibition and shelf-life elongation of Pacific white shrimp during refrigerated storage

Abstract

The efficacy of pulsed electric field (PEF) along with the treatment of 1 % soursop leaf extract (SLE) without and with the aid of vacuum impregnation (VI), followed by modified atmosphere packaging (MAP) on the quality and shelf-life of refrigerated Pacific white shrimp over 18 days of storage at 4 °C was evaluated. Melanosis and color alteration, microbial and chemical, textural and sensorial changes were monitored. The combinations of PEF, SLE, VI and MAP treatments could preserve the textural integrity and inhibited microbial growth more effectively than the control sample. Shrimp with combined hurdles namely PEF-SLE1 (1 %)-VI-MAP1 (60 % CO₂, 30 % N₂, 10 % Ar) and PEF-SLE1-MAP1 showed lower alterations in pH (7.68 and 7.87), total volatile base content (19.27 and 23.80 mg N/100 g), peroxide value (3.8 and 4.06 mg cumene hydroperoxide/kg) and thiobarbituric acid reactive substances (TBARS) (2.91 and 3.19 mg MDA/kg), respectively, after 18 days of refrigerated storage. Nonetheless, the control sample kept for the same period had the higher changes of pH (9.25), total volatile base content (35.19 mg N/100 g), peroxide value (6.23 mg cumene hydroperoxide/kg) and TBARS value (5.07 mg malonaldehyde/kg). The identification of 29 volatile organic compounds (VOCs) revealed that the control had the highest degree of spoilage. Additionally, the sensory evaluation confirmed that the treated samples, particularly PEF-SLE1-VI-MAP1, was generally considered ‘acceptable’ after 18 days of storage. Overall, the integration of PEF, 1 % SLE with VI and MAP1 demonstrated the potential in mitigating melanosis and lengthening the shelf-life of shrimp. These findings validate the use of alternative natural extract and non-thermal techniques to maintain the quality of refrigerated seafoods.

Industrial relevance

Pacific white shrimp are susceptible to melanosis and microbial spoilage, causing substantial economic loss for shrimp farmer and industry. The application of natural additives, particularly plant extracts such as soursop leaf extract, offers a promising means for shrimp quality maintenance. Pretreatment of the shrimp with PEF facilitates the creation of micro-pores in the shrimp shell, thereby enhancing the penetration of active compounds from the plant extract through vacuum impregnation. The use of selective modified atmosphere packaging retards melanosis, growth of certain spoilage bacteria, and lipid oxidation. This is attributed to the combined effects of different gases, where CO₂ may hinder the metabolic activity of the dorminant aerobic bacteria, extending the lag phase and lowering the pH due to carbonic acid formation when CO₂ reacts with the moisture on the shrimp surface. Nitrogen and argon are inert gases and help prevent lipid oxidation and displace oxygen, which plays a key role in melanosis. Therefore, this integrated hurdle approach can potentially be an effective method for quality preservation and shelf-life extension of shrimp and other crustaceans, ensuring both product safety and quality for consumers.