FEASIBILITY STUDY ON THE DEVELOPMENT OF AN ON-PACKAGE FRESHNESS INDICATOR FOR BUFFALO MILK RICOTTA CHEESE
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Date
2022
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ICAR-NDRI, KARNAL
Abstract
Ricotta is a soft, mild- flavored, unripened variety of whey cheese. Ricotta is a protein coprecipitate
having high moisture content. Ricotta has a short shelf life due to its inherent quality
like high moisture and low salt content. Attempts had been made previously to develop pHbased
freshness indicator for Ricotta cheese which could not be successful. Therefore, present
research work was undertaken to develop safe and ready to use chemo-responsive dye-based
freshness indicator to monitor quality of buffalo milk Ricotta cheese. Initially, Ricotta cheese
was stored in PET and glass jar at 5±1°C and changes in physico-chemical, sensory and
microbial attributes were monitored. Moisture, water activity, pH sensory scores were
significantly (p<0.05) decreased whereas acidity, TVB-N, standard plate count, yeast and
mould count significantly (p<0.05) increased during storage of Ricotta cheese at 5±1°C. After
12 days, buffalo milk Ricotta cheese was unacceptable in terms of sensory and microbiological
quality. No significant difference (p<0.05) was observed for physico-chemical, sensorial and
microbiological changes of Ricotta cheese during storage packaged in two different packaging
materials viz., PET and glass jar. To fabricate chemo-responsive dye-based freshness indicator
for Ricotta cheese, preliminary trials were conducted using natural pigment (anthocyanin)
based freshness indicator but colorimetric changes observed were statistically non-significant
(p<0.05) for stored Ricotta samples. Subsequently, trials were conducted to standardize
preparation protocols for ready to use freshness indicators using 3 different synthetic dyes.
Based on the results obtained, suitable dye was selected for indicator fabrication. Suitable
carrier materials were optimized to immobilize the selected dyes to form gel strips. During
storage conditions i.e. 5±1°C, selected indicator labels (M1 and M2) were attached inside the
storage containers of buffalo milk Ricotta cheese for their real time performance evaluation
and estimation. It was found that the yellowness index of both indicator labels was positively
correlated with color change, titratable acidity, standard plate count, yeast and mould and
coliform count content while it was negatively correlated with the pH of Ricotta cheese.
Regression equation was developed to estimate the relationship of indicator label response in
terms of ΔE with suitable parameters. It can be concluded that the freshness indicator labels
could be successfully developed for monitoring in-package quality of Ricotta cheese. Total
volatile base nitrogen and ammonia may be considered as main responsible component for
changing color of developed freshness indicator.