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Purpose The purpose of this paper was to study the color change kinetics of lac dye in response to aldehydes, carbon dioxide and other food spoilage metabolites for its potential application in intelligent food packaging. Design/methodology/approach UV–Vis spectroscopy was used to study the color change of dye solution. Ratio of absorbance of dye solution at 528 nm (peak of ionized form) to absorbance at 488 nm (peak of unionized form) was used to study the color change. Color change kinetics was studied in terms of change in absorbance ratio (A528/A488) with time using zero and first-order reaction kinetics. Lac dye-based indicator was prepared to validate the result of study for monitoring quality of strawberries. Findings Lac dye was orange-red in acidic medium and purple in alkaline medium. Color change of dye in response to benzaldehyde followed zero-order reaction kinetics, whereas for carbon dioxide first-order model was found best. No color change of dye solution was observed for alcohols, ketones and sulfur compounds. In the validation part, the color of the indicator label changed from purple to orange when the strawberries spoiled. Originality/value The study expands application area for lac dye as sensing reagent in intelligent food packaging for spoilage or ripeness detection of fruits and vegetables.

Purpose This paper aims to study the color change kinetics of lac dye in response to pH and food spoilage metabolites (ammonia, lactic acid and tyramine) for its potential application in intelligent food packaging. Design/methodology/approach UV-Vis spectroscopy was used to study the color change of dye solution. Ratio of absorbance of dye solution at 528 nm (peak of ionized form) to absorbance at 488 nm (peak of unionized form) was used to study the color change. Color change kinetics was studied in terms of change in absorbance ratio (A528/A488) with time using zero- and first-order reaction kinetics. An indicator was prepared by incorporating lac dye in agarose membrane to validate the result of study for monitoring quality of raw milk. Findings Dye was orange-red in acidic medium (pH: 2 to 5) and exhibited absorbance peak at 488 nm. It turned purple in alkaline medium (pH: 7 to10) and exhibited absorbance peak at 528 nm. The change in absorbance ratio with pH followed zero-order model. Acid dissociation constant (pKa) of dye was found to be 6.3. Color change of dye in response to ammonia and tyramine followed zero-order reaction kinetics, whereas for lactic acid, the first-order model was found best. In the validation part, the color of the indicator label changed from purple to orange-red when the milk gets spoiled. Originality/value The study opens a new application area for lac dye. The results suggest that lac dye has potential to be used as an indicator in intelligent food packaging for detection of spoilage in seafood, meat, poultry and milk.

Shellac is a physically refined form of lac resin, a natural biopolymer of animal origin obtained from tiny insects feeding on the sap of specific host trees. Shellac, in its basic form, is a polyester macromolecule composed of inter and intra esters of polyhydroxy aliphatic and sesquiterpene acids. It has been used in several industries for ages due to its exceptional properties such as film-forming, adhering, bonding, thermoplasticity, water-resistance and easy solubility in spirit and aqueous alkali solvents. From the beginning of the 21

Physical properties of grains play an important role in the design of material-handling equipment, and functional properties of the flour are crucial from product development point of view. In the present study, physical properties of soaked soybean and functional properties of germinated soy flour was studied. Soybean seeds were soaked in distilled water (30 ± 1 °C) for 4 h. Change in physical properties and moisture content of soybean during soaking was monitored. Results showed that linear dimensions (length, width, thickness), surface area and moisture content of the soybean increased significantly (p

Infrared (IR) radiations are an important source of energy used in the food industry for a wide range of applications such as drying, roasting, pasteurization, blanching, peeling, and removal of antinutrients from legumes. IR drying can be combined with other drying methods such as hot air, vacuum, microwave, and freeze drying to augment the speed of the process and also to get better results. The review puts forward a critical discussion on the principle, applications, and comparative performance of IR energy for drying a range of food materials including grains, fruits, vegetables, and sea food in the recent past. The effects of process variables on energy consumption, drying time, rate of drying, and quality of the dried product are explained in detail. Model calculations for penetration depth of IR in food materials and for heat and mass transfer are also explained. Thin layer drying models to govern kinetics of drying under different configuration of infrared drying systems are also reviewed. The insights presented by this review would help in better understanding and proper selection of process variables for design of advanced IR drying systems.

A study was undertaken to make greaseproof packaging paper using banana pseudostem fiber. Kraft pulp produced from banana fiber was beaten to the freeness of 60°SR and 70°SR, and handsheets (40 ± 1...