Differential Scanning Calorimetry DSC can be used to

Differential Scanning Calorimetry (DSC) can be used to measure the rate of staling quantitatively [18]. Another way to quantify staling is X-Ray crystallography study, specifically the crystalline nature of the starch in the system. Starches appear as amorphous in afreshly baked bread but gradually restructure to crystalline state during storage. The re-crystallization is reflected in X-Ray Diffraction (XRD) patterns. Therefore, X-Ray crystallography can be used to determine molecular organization of starch in bread [19]. X-Ray crystallography can be correlated with DSC for determining the increase in crystallinity during storage of bread. In conjunction with DSC, X-Ray crystallography can also be used in the analysis of the effect of xylanase on the whole wheat bread. The present work was undertaken to find out the effect of xylanase on (i) whole wheat bread prepared using xylanase (produced in small scale laboratory fermenter using Penicillium citrinum MTCC 9620); (ii) the evaluation of physicochemical, textural, thermal and micro-structural properties of fresh bread prepared using xylanase; (iii) the addition of xylanase on staling properties of bread during storage at ambient (25°C) and cold (4°C) temperature.
Materials and methods
Result and discussion
Conclusion The various bread qualities with respect to specific volume and moisture, textural properties, color, thermal and sensory properties etc. were improved by the addition of xylanase. Firmness and enthalpy values of stored bread samples were nicely fitted in Avrami equation. The calculated values are in agreement with experimental values. Xylanase addition resulted reduced rate of staling in bread. A 20% c-kit inhibitor of limiting firmness (Fα) was observed in bread containing xylanase. During storage, bread containing xylanase was softer as compared to control. From the analysis of various staling properties examined, it may be inferred that bread stales at both ambient (25°C) and cold (4°C) temperature, but the rate was lowest at 4°C in bread containing xylanase. By the addition of partially purified xylanase, the color, texture and sensory properties of whole wheat bread is improved.
Acknowledgements G. Ghoshal and U.S. Shivhare are thankful to AICTE, New Delhi, India (Grant sanction no. 8023/BOR/RPS-2/2006-07; dated 26/02/2007) for providing financial support to carryout this work. Authors are also thankful to Prof. Tejbir Singh from Department of Chemistry, Panjab University, Chandigarh for his generous help in interpreting FTIR results.
Introduction To date, ∼30,000 phytochemicals have been identified, of which 5000–10,000 are present in the food consumed in the human diet [1]. There is evidence that diets rich in fruit and vegetables could have a protective effect against a number of cancers [2] and other chronic health conditions such as cardiovascular disease [3]. Phytochemicals have many uses in the therapeutic, pharmaceutical, and food industries. Roselle calyces (RC) (Hibiscus sabdariffa L.) are a tropical plant in the Malvaceae family and is known in Egypt as Karkadah. It is probably a native of West Africa and is now widely cultivated throughout the tropics and subtropics, e.g., Sudan, China, Thailand, Egypt, Mexico, and the western part of India [4]. RC are one of the major Egyptian crops and is used in food, drinks, and cosmetics. Dried RC are commercially available and appreciated to obtain concentrated extracts which might be used in the food and pharmaceutical industries for color and heath benefits. It has been shown that ingestion of infusions of RC may help to reduce chronic diseases such as diabetes mellitus, dyslipidemia, and hypertension. This could be due to the activity of some compounds, mainly flavonoids and anthocyanins, found as natural antioxidants in Roselle calyces extract (RCE) [5]. RC anthocyanins might be used as a natural food colorant [6], as it is safer than most synthetic dyes that contain azo functional groups and aromatic rings, that may have negative effects on health including allergic and asthmatic reactions [7], DNA damage [8], and hyperactivity [9]. Some synthetic dyes are even considered to be potentially carcinogenic and mutagenic to humans [10].