The development of green material in the last decade has been increased, which tends to reduce the impact of humans on the environment. Starch as an agro-sourced polymer has become very popular recently due to its characteristics, such as wide availability, low cost, and total compostability without toxic residues. Starch is the most abundant organic compound found in nature after cellulose. Starches are inherently unsuitable for most applications and, therefore, must be modified physically and/or chemically to enhance their positive attributes and/or to minimize their defects. Modification of starches is generally carried out by using physical methods that are simple and inexpensive due to the absence of chemical agents. However, chemical modification involves the exploitation of hydroxyl group present in the starches that brings about the desired results for the utilization of starches for specific applications. All these techniques have the tendency to produce starches with altered physicochemical properties and modified structural attributes for various food and nonfood applications. This paper reviews the recent knowledge and developments using physical modification methods, some chemical modification methods, and a combination of both to produce a novel molecule with substantial applications, in food industry along with future perspectives.

The behavior of the Goos-Hänchen (GH) shifts in the reflected and transmitted light beam which is incident on a cavity containing an intracavity medium of three-level or four-level atoms with electromagnetically induced transparency (EIT) is discussed. We report a coherent control of the GH shift in a fixed configuration or device via superluminal and subluminal wave propagation. For superluminal wave propagation, we observe negative GH shifts in the reflected part of the incident light whereas the shifts are positive in the transmitted light beam. This corresponds to the negative group index of the cavity in the former case and positive group index of the cavity in the latter. For subluminal wave propagation, the behavior of the GH shifts in the reflected light changes and positive shifts appear; however, the GH shifts in the transmitted light remains positive. The corresponding group index of the cavity is positive in both cases.

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The influence of the Kerr nonlinearity on the group index of a dispersive intracavity medium is revisited using a Raman gain based scheme to obtain amplitude control of the Goos-Hänchen (GH) shift in the reflected light. The intracavity medium exhibits a Raman gain process which is accompanied by anomalous dispersion, i.e., superluminal pulse propagation (Dogariu et al 2000 Nature 406 277). In the presence of a Kerr field, the gain-dispersion properties of the intracavity medium are modified, which leads to enhancement in the positive and negative group indices of the medium. The behavior of the GH shift in the reflected light due to the enhancement in the group indices in the presence of the Kerr field is investigated, and relatively large positive and negative GH shifts can be obtained.

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