K. Narsaiah

Optical biosensors for food quality and safety assurance—a review

Food quality and safety is a scientific discipline describing handling, preparation and storage of food in ways that prevent food borne illness. Food serves as a growth medium for microorganisms that can be pathogenic or cause food spoilage. Therefore, it is imperative to have stringent laws and standards for the preparation, packaging and transportation of food. The conventional methods for detection of food contamination based on culturing, colony counting, chromatography and immunoassay are tedious and time consuming while biosensors have overcome some of these disadvantages. There is growing interest in biosensors due to high specificity, convenience and quick response. Optical biosensors show greater potential for the detection of pathogens, pesticide and drug residues, hygiene monitoring, heavy metals and other toxic substances in the food to check whether it is safe for consumption or not. This review focuses on optical biosensors, the recent developments in the associated instrumentation with emphasis on fiber optic and surface plasmon resonance (SPR) based biosensors for detecting a range of analytes in food samples, the major advantages and challenges associated with optical biosensors. It also briefly covers the different methods employed for the immobilization of bio-molecules used in developing biosensors.

Measurement techniques and application of electrical properties for nondestructive quality evaluation of foods—a review

Non-destructive systems are recent trends for quality evaluation of fruits and vegetables. Information on post-harvest variations in electrical properties is needed to develop new instruments for this purpose. Electrical properties are finding increasing application in agriculture and food processing industries. Knowledge of dielectric properties of foods as a function of moisture content and temperature is essential in the design and control of drying systems. As simple, rapid and non-destructive measuring techniques, dielectric spectroscopy provides information about the dielectric response of materials to electromagnetic field. Electrical properties of agricultural materials have been of interest for many years. The interest in dielectric properties of materials has historically been associated with the design of electrical equipment. This review paper covers theoretical aspects of different electrical properties, their measurement techniques, applications of dielectric properties in agriculture/food processing sector and potential applications of thermal imaging (TI) for quality and safety assessment in food processing. The values of dielectric properties of a number of products including food grains, fruits and vegetables, and meat and meat products are presented in table form. This comprehensive coverage will be useful for academic, scientific and industrial community in treating and applying the facts in developing/testing new processes and products based on electromagnetic energy application.

Nondestructive methods for quality evaluation of livestock products.

The muscles derived from livestock are highly perishable. Rapid and nondestructive methods are essential for quality assurance of such products. Potential nondestructive methods, which can supplement or replace many of traditional time consuming destructive methods, include colour and computer image analysis, NIR spectroscopy, NMRI, electronic nose, ultrasound, X-ray imaging and biosensors. These methods are briefly described and the research work involving them for products derived from livestock is reviewed. These methods will be helpful in rapid screening of large number of samples, monitoring distribution networks, quick product recall and enhance traceability in the value chain of livestock products. With new developments in the areas of basic science related to these methods, colour, image processing, NIR spectroscopy, biosensors and ultrasonic analysis are expected to be widespread and cost effective for large scale meat quality evaluation in near future.

The effect of salt, extract of kinnow and pomegranate fruit by-products on colour and oxidative stability of raw chicken patties during refrigerated storage.

Use of extracts of kinnow and pomegranate by-products as source of natural antioxidant in salted chicken patties during refrigerated storage was evaluated. Five treatments viz., I. Control (meat), II.MS (meat + 2%salt), III. KRP (meat + 2% salt + 2% kinnow-rind-powder extract), IV. PRP (meat + 2% salt + 2% pomegranate-rind-powder extract), and V. PSP (meat + 2% salt + 2% pomegranate seed powder extract). Results showed that salt significantly (P < 0.05) reduced lightness and yellowness but increased chroma and TBARS values. The average increase in TBARS was significantly (P < 0.05) higher in MS (114%) and Control (108%) but lower in KRP (90%), PRP (81%) and PSP (73%). Lipid oxidation (TBARS) in salted meat during the storage was significantly reduced (P < 0.05) by KRP (39%), PRP (43%) and PSP (68%). Thus it was observed that addition of 2% salt accelerated the TBARS formation but inclusion of extracts of pomegranate and kinnow fruit by-products effectively counteracted this effect. The overall antioxidant effect was in the order of PSP>PRP>KRP. Further a significant (P < 0.05) negative correlation between total phenolics contents and TBARS values was also observed. Therefore, it was concluded that extracts of these fruit by-products have potential to be used as natural antioxidants to minimize the oxidative problems in poultry meat products.

Evaluation of quality characteristics of chicken meat emulsion/nuggets prepared by using different equipment

Chicken meat emulsions prepared using food processor (FP), an indigenous meat cutter (MC) and bowl chopper (BC) were evaluated for physicochemical, texture and electron microscopic studies (SEM). Product yield, emulsion stability, hydration properties and gel strength (N) were significantly (P < 0.05) higher in BC. Total fluid release (TFR), water release (WR) and fat release (FR) was lowest in BC. Significantly (P < 0.05) higher lightness (L) in BC and redness (a) in FP emulsion were observed. Higher firmness, gumminess, chewiness and cohesiveness were observed in BC emulsion. SEM studies revealed a dense and compact protein matrix characteristic of heat induced protein gels. All micrographs showed structures that are compatible with fat globules, muscle fiber, meat protein matrix and heat induced gel/protein matrix. Sensory evaluation showed no significant difference between three treatments for colour, flavour, texture and acceptability scores. Thus, food processor and indigenously developed meat cutter found suitable for producing a stable chicken meat emulsion required for indigenous meat products.

Tenderizing effect of blade tenderizer and pomegranate fruit products in goat meat

Toughness of goat meat is a major problem with regard to consumer acceptance. Keeping this in view a blade tenderizer was developed for tenderization of goat meat. Pomegranate fruit products were also explored for tenderization effect on goat meat. Tenderization of goat meat with pomegranate seed powder improved the textural properties marginally with slight adverse colour change and taste. Samples treated with PRP got lower score for colour in sensory evaluation and there was adverse effect on taste of treated meat. Blade tenderization and 4% PSP proved better for tenderization and were compared with control and 0.2% papain in goat meat chunks. The cooked samples treated with papain and blade incisions got better sensory scores and required lesser shear force compared to 4% PSP and control. Overall the papain treated meat was superior in terms sensory attributes followed by blade incision and PSP. The results suggested that the blade incisions can be used for tenderization of goat meat. Pomegranate seed powder maybe considered for mixing with other spices to marinate goat meat mainly for its beneficial effects.