Revathy Baskaran

Essential oil based nanoemulsions to improve the microbial quality of minimally processed fruits and vegetables: A review

Due to the convenience and nutritional value, minimally processed fruits and vegetables (MPFV) are one of the rapid growing sectors in the food industry. However, their microbiological safety is a cause of great concern. Essential oils (EOs), known for potent antimicrobial efficacy have been shown to reduce microbial load in MPFV, but their low water solubility, high volatility and strong organoleptic properties limit their wide use. Encapsulating EOs to nanoemulsion offers a viable remedy for such limitations. Due to the unique properties of the EOs nanoemulsion, there has been an increasing interest in their fabrication and use in food system. The present review article encompasses the overview of the prominent microflora present in MPFV, the recent developments on the fabrication and stability of EOs based nanoemulsion, their in vitro antimicrobial activity and their application in MPFV. This review also discusses the EOs based nanoemulsions antimicrobial mechanism of action and their regulatory issues related to their use. Application of EOs based nanoemulsion either as washing disinfectant or with incorporation into edible coatings have been shown to considerably improve the microbial quality and safety of MPFV. This efficacy has been further shown to increase when combined with other hurdles. However, further studies are required on the toxicity of EOs based nanoemulsion to assure its commercial exploitation.

Bioactive chitosan based coatings: functional applications in shelf life extension of Alphonso mango – a sweet story

Abstract Chitosan-based coating (M4F2) was used successfully to delay ripening and prolong shelf-life of rapidly perishable and expensive Alphonso mango fruits stored at 30 ± 3°C and 40–50% RH for 15 days. Matured raw Alphonso mango fruits were simple dip treated/coated and air dried with our newly developed chitosan based formulation (for industry) with additives. Samples were taken at regular intervals for routine analysis of fruits. Results indicated that M4F2 coating could decrease the decay incidence loss along with delay the change in color of mango fruit during storage but not physiological steady weight loss. Interestingly, sensory evaluation indicated that quality of mango was enhanced slight significantly to more sweetness and better aroma by M4F2 coating compared to uncoated control fruits. Further, our M4F2 coating formulation may act as an important potentiator of flavor compounds of mango as well as controlling organic acids and sugars, which are key components in the perception of mango flavor. Understanding the chemical components that contribute to flavor perception of the fruit is necessary for post-harvest storage technology. This information is also important to study chitosan/derivatives elicitation in molecular level to improve mango flavor as well as in identification of genes responsible for flavor quality. The scientific story behind this effective chitosan based coating formulation development has been discussed.

Thermal Processing Alters the Chemical Quality and Sensory Characteristics of Sweetsop (Annona squamosa L.) and Soursop (Annona muricata L.) Pulp and Nectar.

The objective of this study was to investigate the effect of thermal processing on the chemical quality and sensory characteristics of Annona squamosa L. and Annona muricata L. fruit pulps and nectar. The fruit pulps were pasteurized at 85 °C for 20 min and nectar prepared as per Food Safety and Standards Authority of India (FSSAI) specifications. The chemical composition of fresh and heated pulps of A. squamosa and A. muricata showed that compared to fresh, the chemical profile and sensory profile changed in heated samples and nectar. The free and bound phenolics of A. squamosa increased in heated pulp (127.61 to 217.22 mg/100 g and 150.34 to 239.74 mg/100 g, respectively), while in A. muricata, free phenolics increased very marginally from 31.73 to 33.74 mg/100 g and bound phenolics decreased from 111.11 to 86.91 mg/100 g. This increase in phenolic content may be attributed to the perception of bitterness and astringency in A. squamosa pulp on heating. In electronic tongue studies, principal component analysis (PCA) confirmed that the fresh and heated pulps had different scores, as indicated by sensory analysis using qualitative descriptive analysis (QDA). E-tongue analysis of samples discriminated the volatile compounds released from the heated A. squamosa and A. muricata fruit pulps and nectar in their respective PCA plots by forming different clusters.

Post-Harvest Ripening Changes in Wood Apple (Feronia elephantum Corr), An Underutilized Fruit

Biochemical changes in wood apple fruit (Feronia elephantum Corr.) were studied at three different stages (unripe, semiripe, and ripe). Like most of the ripening fruits, the major changes observed were the increase in total sugars (3.2 to 4.9 g/100g) and decrease in acidity from (3.5 to 3.2 g/100g). Among the free sugars estimated by high performance liquid chromatography (HPLC), sucrose (0.85 g/100g) was predominant at all stages of ripening. Among organic acids, citric acid was detected as the major organic acid in the unripe (2.2 g/100g fresh weight basis (FW)) and ripe (1.6 g/100g FW) fruit. Unlike various other fruits, the total soluble solids were reduced upon ripening from 20.4 to 14.0 °Brix. The total phenolics increased from 9.7 to 15.7 mg/g and the total protein also increased from 8.7 to 9.6 g/100g. It was also found that the wood apple contained more phenolics in the bound form than the free form. A high correlation was obtained between the reducing power and the total phenolic content.