Bhesh Bhandari

Evaluation of encapsulation techniques of probiotics for yoghurt

Abstract The health benefits provided by probiotic bacteria have led to their increasing use in fermented and other dairy products. However, their viability in these products is low. Encapsulation has been investigated to protect the bacteria in the products environment and improve their survival. There are two common encapsulation techniques, namely extrusion and emulsion, to encapsulate the probiotics for their use in the fermented and other dairy products. This review evaluates the merits and limitations of these two techniques, and also discusses the supporting materials and special treatments used in encapsulation processes.

Implication of glass transition for the drying and stability of dried foods

Dry products obtained from most of the common drying processes are predominantly in a glassy amorphous form. The mobility of the solid matrix in this state is highly limited. For the product to be stable for long periods of storage, this physical state should not alter with time. When the temperature is above glass transition temperature (T-g) an amorphous solid exists in a rubbery state. In this state, the molecular mobility of the matrix and the reactants are accelerated, which results in an increased rate of physicochemical changes in dried products, such as sticking, collapse, caking, agglomeration, crystallisation, loss of volatiles, browning and oxidation. These changes play an important role in the ability to both process and store dried food products. This paper reviews the importance of T-g in relation to drying process and dried foods

Encapsulation Efficiency of Food Flavours and Oils during Spray Drying

Microencapsulation is a rapidly expanding technology which is a unique way to package materials in the form of micro- and nano-particles, and has been well developed and accepted within the pharmaceutical, chemical, food and many other industries. Spray drying is the most commonly used encapsulation technique for food products. A successful spray drying encapsulation relies on achieving high retention of the core materials especially volatiles and minimum amounts of the surface oil on the powder particles for both volatiles and non-volatiles during the process and storage. The properties of wall and core materials and the prepared emulsion along with the drying process conditions will influence the efficiency and retention of core compounds. This review highlights the new developments in spray drying microencapsulation of food oils and flavours with an emphasis on the encapsulation efficiency during the process and different factors which can affect the efficiency of spray drying encapsulation.

Problems associated with spray drying of sugar rich foods

ABSTRACT Stickiness is a major reason that limits the spray drying of various sugar-rich food products.Higher hygrmopicity of amorphous powder, increase in solubility of sugars with temperature, and lower melting point and glass transition temperature, contribute to the aickiness problem. So far, the glass transition temperature has been widely accepted as a ben indicator for stickiness. There are various manawm that have been applied to spray dry such product. Some of them are the addition of drying aids, modilication of drier design and use of mild drying temperature conditions. This review paper highlights the major research works that deal with the stickiness property of sugar-rich foods.

Nano-Emulsion Production by Sonication and Microfluidization—A Comparison

The efficiency of sonication and microfluidization to produce nano-emulsions were evaluated in this study. The purpose was to produce an oil-in-water nano-emulsion of d-limonene to apply it in the next step for nano-particle encapsulation. In the entrapment and retention of volatiles or for the microencapsulation efficiency, emulsion size is one of the critical factors. In this study, a bench-top sonicator and an air-driven microfluidizer were used to prepare the emulsions. Results show that, while both methods were capable of producing nano-emulsions of the size range of 150–700 nm, the microfluidizer produced emulsions with narrower size distributions and sonication was more convenient in terms of operation and cleaning. In general, the size of the emulsions decreased with increasing sonication time, or the microfluidization pressure and duration. However, for both sonication and microfluidization, optimal conditions were necessary for emulsification beyond which the emulsion sizes would either increase or have little change with further processing.

SPRAY DRYING OF CONCENTRATED FRUIT JUICES

ABSTRACT Two spray dryers were tested to obtain powders from concentrated juices of blackcurrant, apricot, raspberry, with different maltodextrins as drying-aid agents. Composition of fruit juices and dextrose equivalent for maltodextrin are considered. Best results were obtained for a ratio juice to maltodextrin DE6 of 65/35 for blackcurrant, of 60/40 for apricot and 55/45 for raspberry, and low air temperatures (160–90°C). A compromise must be found between the ratio fruit juice to additives, the drying yield and the cost of raw materials.

STICKINESS IN FOODS: A REVIEW OF MECHANISMS AND TEST METHODS

Problems associated with the stickiness of food in processing and storage practices along with its causative factors are outlined. Fundamental mechanisms that explain why and how food products become sticky are discussed. Methods currently in use for characterizing and overcoming stickiness problems in food processing and storage operations are described. The use of glass transition temperature-based model, which provides a rational basis for understanding and characterizing the stickiness of many food products, is highlighted.

Hydrocolloid Gel Particles: Formation, Characterization, and Application

Hydrocolloid gel particles of micron and sub-micron size are particularly attractive for use in many applications in the food, agricultural, pharmaceutical, and chemical industries, due to their biocompatibility, perception as “natural” materials, and soft-solid texture. Industrial applications for such particles include uses as texturizers in confectionery and cosmetic products, slow-release encapsulation agents for flavors, nutrients, and pharmaceutical products, and thickeners in soups and sauces. Properties such as particle size, hardness, shape, texture, and molecular release rates can be important for individual applications. In addition, product formats will determine specific needs for physical form (e.g. dry or wet) and compatibility with other components. The diverse range of potential applications for hydrocolloid gel particles provide a driver for understanding-led tailoring of raw material and process conditions. This review introduces some of the materials that are used to form hydrocolloid gel particles and the corresponding gel formation mechanisms. One issue of importance in the production of hydrocolloid gel particles is the control of particle properties, such as release profiles, strength, and detectability within products. An alternative technique to traditional methods of hydrocolloid gel particle production is evaluated and a model for control of particle size, and subsequently other particle properties, is proposed. Key properties of hydrocolloid gel particles are identified and characterization methods for evaluating these properties are described.

Optimization of Supercritical Carbon Dioxide Extraction of Flaxseed Oil Using Response Surface Methodology

The optimal conditions for the supercritical carbon dioxide (SC-CO2) extraction of flaxseed oil from flaxseed were determined using response surface methodology (RSM). A second-order regression for rotation-orthogonal composite design was used to study the effects of three independent variables: extraction pressure (MPa), extraction temperature (oC) and CO2 flow rate (L/h) on the yield of flaxseed oil. The independent variables were coded at five levels and their actual values selected on the basis of preliminary experiments. The results indicated that the yield of flaxseed oil was beyond 29% at a probability of 95% in the range of extraction pressure: 38.6-42.3 MPa, extraction temperature: 52.3-57.0 oC, and CO2 flow rate: 27.8-31.2 L/h. The optimal extraction conditions were extraction pressure of 41 MPa, extraction temperature of 56 oC and CO2 flow rate of 31 L/h according to the analysis of response surface. In this condition, the experimental yield of flaxseed oil was 29.96%, which was close to the predicted value of 30.52%.

A SEMI-EMPIRICAL APPROACH TO OPTIMISE THE QUANTITY OF DRYING AIDS REQUIRED TO SPRAY DRY SUGAR-RICH FOODS

ABSTRACT A semi-empirical linear equation has been developed to optimise the amount of maltodextrin additive (DE 6) required to successfully spray dry a sugar-rich product on the basis of its composition. Based on spray drying experiments, drying index values for individual sugars (sucrose, glucose, fructose) and citric acid were determined, and using these index values an equation for model mixtures of these components was established. This equation has been tested with two sugar-rich natural products, pineapple juice and honey. The relationship was found to be valid for these products.