Tanushree Maity

Quality Characteristics and Glass Transition Temperature of Hydrocolloid Pre-Treated Frozen Pre-Cut Carrot

The effect of hydrocolloid pre-treatment, i.e., pectin, carboxy methyl cellulose, xanthan gum and sodium alginate on textural properties, drip losses and sensory quality as well as on glass transition temperature (Tg′′′) of the frozen-thawed pre-cut carrots was studied. Untreated frozen samples showed detrimental effects in texture and also excessive drip losses while the carrot tissue integrity was well retained in the hydrocolloid pre-treated samples. As the concentration of the hydrocolloid increased, hardness and fracturability were also found to increase. However, adhesiveness was observed to follow a reverse trend. Xanthan gum (0.4%) resulted in higher texture retention than other hydrocolloids used as well as than the control samples. Hydrocolloids imparted lightness and higher red and yellowness to the carrot samples due to reduced solute mobility and moisture conditioning effects. Overall acceptability of the hydrocolloid pre-treated samples was found to be more than the experimental control samples. All the hydrocolloids were found to be effective in increasing the Tg′′′ to an extent, −2.73 to −0.28°C compared with Tg′′′ (−5.4°C) of untreated carrot samples. Tg′′′ increased to almost 74% in CMC (0.4%) pre-treated samples. The maximum enhancement was found in carboxy methyl cellulose followed by pectin, sodium alginate, and xanthan gum. The threshold concentrations in terms of sensory attributes were determined for optimal conditioning of the product prior to freezing.

Effect of Hydrocolloid Pre-Treatment on Instrumental and Sensory Texture Attributes of Frozen Carrot (Daucus carota)

The effect of different hydrocolloids (pectin, carboxy methylcellulose, xanthan gum, and sodium alginate) pre-treatment used at different concentrations (0.2–0.4%) on instrumental texture parameters as well as on the sensory attributes of frozen-thawed pre-cut carrots was evaluated. Instrumental texture profile analysis of frozen-thawed carrot showed a significant (P < 0.05) increase in cohesiveness with an increase in the concentration of all the hydrocolloids. Nevertheless, the increase in springiness was not significant (P > 0.05) over the untreated control samples, whereas chewiness did not show consistent results with an increase of any of the hydrocolloids. As the concentration of hydrocolloids increased, the firmness values obtained by cutting the frozen-thawed carrot samples with a Warner Bratzler Blade were also found to increase. Higher texture retention after freezing and thawing was observed in xanthan gum (0.4%) pre-treated samples than other hydrocolloids used as well as than the control samples. It increased the firmness up to 196.2% than the control samples. However, 0.3% xanthan pre-treatment gave the best sensory results. Sensory acceptability increased on increasing the pectin and carboxy methylcellulose concentrations, while lower concentration levels of alginate pre-treatment showed higher sensory preference than the higher concentration levels. Based on the results, untreated frozen samples suffered from a detrimental texture and sensory deterioration during 15 months of frozen storage. The carrot tissue integrity was well retained during frozen storage in the hydrocolloid pre-treated samples.

Effect of preconditioning on physicochemical, microstructural, and sensory quality of vacuum-fried jackfruit chips

ABSTRACT The effect of preconditioning steps in terms of either freezing or partial drying on the quality of vacuum-fried jackfruit (JF) chips was evaluated. Prepartial drying process of the JF bulb slices resulted in the lowest moisture content in the vacuum-fried chips. The rate of oil uptake by JF bulb slices was found to be almost same in control and prefrozen samples during frying process. However, prepartial drying of slices resulted in a slower rate of oil absorption. The total carotenoid content was found to be 1.81, 0.96, and 1.87 mg/100 g (db) in control, prepartially dried and prefrozen JF chips, respectively. The Hunter L-value of control, prepartially dried, and prefrozen chips was found to be 52.3, 39.4, and 48.5, respectively. The a-value was found to increase, whereas the b-value decreased during vacuum frying in all the JF chip samples, irrespective of preconditioning type adopted. Prefrozen JF chips were found to have highest crispy texture in terms of lowest instrumental breaking force compared to the control and prepartially dried JF chips. Prefrozen JF chips were found to have lowest bulk density and highest porosity. The micrograph of prepartially dried JF chips depicted dense and shriveled structure, whereas a porous structure in prefrozen chips. The preconditioning protocols of partial drying and freezing were found to affect the overall sensory acceptability scores significantly (P < 0.05), with a high acceptability of prefrozen JF chips.

Use of hydrocolloids as cryoprotectant for frozen foods

ABSTRACT Freezing is one of the widely used preservation methods to preserve the quality of food products but it also results in deteriorative changes in textural properties of food which in turn affects its marketability. Different foodstuffs undergo different types of changes in texture, taste and overall acceptability upon freezing and subsequent frozen storage. Freezing and thawing of pre-cut or whole fruits and vegetables causes many deleterious effects including texture and drip losses. The major problem in stability of ice-cream is re-crystallization phenomena which happens due to temperature fluctuations during storage and finally impairs the quality of ice-cream. Frozen storage for longer periods causes rubbery texture in meat and fish products. To overcome these problems, hydrocolloids which are polysaccharides of high molecular weight, are used in numerous food applications involving gelling, thickening, stabilizing, emulsifying etc. They could improve the rheological and textural characteristics of food systems by changing the viscosity. They play a major role in retaining texture of fruits and vegetables after freezing. They provide thermodynamic stability to ice cream to control the process of re-crystallization. Hydrocolloids find application in frozen surimi, minced fish, and meat products due to their water-binding ability. They are also added to frozen bakery products to improve shelf-stability by retaining sufficient moisture and retarding staling. Various hydrocolloids impart different cryoprotective effects to food products depending upon their solubility, water-holding capacity, rheological properties, and synergistic effect with other ingredients during freezing and frozen storage.

Development of Tomato Sambar Paste Stabilized by Hurdle Technology and Evaluation of Storage Stability

The study was undertaken to develop ready-to-use sambar paste stabilized by various hurdles vis a vis water activity, pH, temperature, and preservative. Physico-chemical characteristics such as pH, titratable acidity (TA), color changes, and microbiological profiles were monitored during four months of storage at 28 ± 3°C and 37°C. A Hedonic test was used to evaluate consumer perception and acceptability of sambar paste during storage. Color analysis showed significant (p < 0.05) decrease in the lightness (L) and yellowness (b*), while redness (a*) of the paste increased during storage at both the storage temperatures. Sensory evaluation showed that there was no significant difference (p > 0.05) in most of the sensory attributes during storage except color. The sambar paste was found to be microbiologically safe for four months at 37°C.