Effect of pulsed light treatment on the phytochemical, volatile, and sensorial attributes of lactic-acid-fermented mulberry juice

Emmanuel Kwaw,Yongkun Ma,William Tchabo,Maurice Tibiru Apaliya,Augustina Sackle Sackey,Meng Wu,Lulu Xiao

doi:10.1080/10942912.2018.1446024

Emmanuel Kwaw, Yongkun Ma + Show 5 more

Open Access

https://doi.org/10.1080/10942912.2018.1446024

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Abstract

ABSTRACTLactic-acid-fermented mulberry juice (LFMJ) was subjected to pulsed light (PL) treatment at exposure time of 2, 4, and 8 s at high insensitive pulses of 14.0 J/cm2. The effect of PL treatment on the microbial inactivation, physicochemical, phytochemical, volatile, and sensory characteristics of LFMJ was evaluated. It was found that the PL was able to reduce the microbial load to acceptable levels (1.02 ± 0.04 log10 cfu/mL) with no significant impact on the physicochemical properties of LFMJ. It was also observed that the PL treatment caused a slight decrease in anthocyanin concentration at 8 s exposure time. The color difference (∆E) of the juice treated for 2 and 4 s fell below the slightly noticeable range 0.5<ΔE<1.5 while ∆E values for the 8 s (0.55 ± 0.02) and the thermal (0.50 ± 0.02) treated samples were slightly noticeable. The volatile profile and odor activity values were positively affected by increasing the exposure time. The results depict that, under the present experimental conditions, the application of the PL resulted in a fermented juice with superior quality attributes as compared to the thermal treated juice.

Highlights

Mulberry is a monoecious plant cultivated in Africa, Asia, Europe, South America, and North America.[1]
The study (Table 1) showed no significant changes (p < 0.05) in the pH, brix, and titratable acidity of the treated samples regardless of the treatment applied compared to the Lactic-acid-fermented mulberry juice (LFMJ)
The foremost outcome on microbial inactivation produced by pulsed light (PL) has been ascribed to the photochemical action of the UV radiation that modifies the structure of the DNA, impaired replication, and gene transcription.[16]

Summary

Introduction

Mulberry is a monoecious plant cultivated in Africa, Asia, Europe, South America, and North America.[1] It belongs to the genus Morus from the Moraceae family. There are 24 species of Morus and one subspecies, with at least 100 known varieties.[2] The fruit has been extensively used in traditional medicine in treating ailments such as malaria, diabetes, hepatitis, dermatitis, atherosclerosis, asthma, and rheumatism.[3] Besides, it is regarded as a nutritious food that varies according to variety, environmental factors, and geographical location.[4] The fruit is very perishable[5] the need to preserve it from postharvest loss To address this challenge, the fruit is often processed into fruit jellies, jam, wines, and nonalcoholic beverage, among others.[6,7]

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