Straightforward process for removal of milk fat globule membranes and production of fat-free whey protein concentrate from cheese whey

A straightforward method for the separation of milk fat globule membrane (MFGM) and production of fat-free whey protein concentrate/isolate from cheese whey has been developed. Lowering of the conductivity of the whey from its initial value of about 5600 μS cm(-1) to about 2000-500 μS cm(-1) via diafiltration with water caused selective precipitation of MFGM when incubated for 30 min at pH 4.2 and 35 °C. The whey proteins remained soluble in the supernatant under these conditions. Experimental evidence suggested that precipitation of MFGM at pH 4.2 was not due to a nonspecific effect of lowering of the conductivity of the whey but due to the specific effect of removal of Ca2+ from the whey. The lipid content of whey protein isolate obtained by this process was <0.2%, and the protein loss was <14%. The method provides an industrially feasible process for the production of fat-free whey protein concentrate/isolate. The MFGM, which is reported to contain bioactive/nutraceutical lipids and proteins, is a valuable byproduct of the process.     

Incompatibility of mixing of proteins in adsorbed binary protein films at the air-water interface.

Competitive adsorption of proteins from several binary protein solutions to the air-water interface has been studied. With a few exceptions, the equilibrium composition of the saturated monolayer of mixed protein films at various bulk concentration ratios did not follow a Langmuir-type competitive adsorption model. The deviation from ideal behavior results from incompatibility of mixing of proteins in the film at the air-water interface. This immiscibility alters the ratio of the binding affinity of the proteins in a protein 1/protein 2/water ternary film compared to that in a protein 1/water and protein 2/water binary film. A method to determine the extent of incompatibility between two proteins in a mixed protein film has been developed. It is shown that the incompatibility index derived for 19 protein 1/water and protein 2/water systems studied show a linear relationship with the absolute difference between Flory-Huggins protein-solvent interaction parameters, that is, /chi(1s) - chi(2)/, of the constituent proteins. On the basis of the evidence, it is theorized that, because of incompatibility, proteins in a mixed protein film at interfaces may undergo two-dimensional phase separation.     

Optimization of the stocking parameters for mud spiny lobster Panulirus polyphagus (Herbst, 1793) capture‐based aquaculture in tropical open sea floating net cages

Mud spiny lobsters, Panulirus polyphagus (Herbst, 1793), were reared at four different stocking sizes and stocking densities in open sea cages to evaluate their effects on growth performance. To evaluate the effect of stocking size on the growth performance, the lobsters were segregated into four different treatment groups according to size and were stocked at a density of 300 animals per cage. To evaluate the effect of stocking density on the growth performance, lobsters of 81–100 g were stocked in four different stocking densities, i.e. 16/m², 24/m², 32/m² and 40/m². The results showed that the growth rate of (60–80 g) size group, was significantly higher compared to the size groups, i.e. 101–120 g and 121–140 g comprising of larger individuals. The final body weight, though significantly higher in 81–100 g as compared to 60–80 g, the growth performance (i.e. weight gain percentage (WG %) and specific growth rate (SGR)) were not significantly different. The density‐dependent influence on growth performance was evident in this study. The WG % and SGR during 90 days’ culture period was significantly higher in 24/m² compared to other groups. This study provides crucial information about the appropriate stocking density and stocking size of lobsters at the field level, which would help to promote sustainable lobster cage farming by maximizing the production potential of the system.     

Phenotypic Diversity of Foliar Traits in Coconut Germplasm*

Coconut palm is a multipurpose crop cultivated in tropics. Diversity in this crop is rich in South Pacific Ocean and Indian Ocean Islands. Foliar traits have not been studied extensively to understand the diversity. Seven traits relevant to wind tolerance, dry matter production and taxonomic discrimination known in palms are used in the study. An attempt was made using Shannon–Weaver index with an objective to understand the level of diversity for these traits in a germplasm collection from diversity hotspot areas. Seven tall groups and four dwarf groups representing seven island territories were studied using 206 individuals. Diversity estimate was the highest in Nicobar tall group whereas it was low in tall genotypes of Fiji and Tonga. Thickness of leaf sheath fiber of weft and warp strands had shown high diversity estimates. Results obtained in this study were analyzed in relation to adaptation, geographical affinity, mating system and taxonomic forms (typica and nana) along with the importance of foliar traits in diversity of coconut. *CPCRI Contribution No. 1181     

Impact of Bran Addition on Water Properties and Gluten Secondary Structure in Wheat Flour Doughs Studied by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy

The aim of this work was to elucidate the underlying physical mechanism(s) by which bran influences whole grain dough properties by monitoring the state of water and gluten secondary structure in wheat flour and bran doughs containing 35–50% moisture and 0–10% added bran. The system was studied with attenuated total reflectance (ATR) FTIR spectroscopy. Comparison of the OH stretch band of water in flour dough with that in H₂O‐D₂O mixtures having the same water content revealed the formation of two distinct water populations in flour dough corresponding to IR absorption frequencies at 3,600 and 3,200 cm^–1. The band intensity at 3,200 cm^–1, which is related to water bound to the dough matrix, decreased and shifted to lower frequencies with increasing moisture content of the dough. Addition of bran to the dough caused redistribution of water in the flour and bran dough system, as evidenced by shifts in OH stretch frequency in the 3,200 cm^–1 region to higher frequencies and a reduction in monomeric water (free water). This water redistribution affected the secondary structure of gluten in the dough, as evidenced by changes in the second‐derivative ATR‐FTIR difference spectra in the amide I region. Bran addition caused an increase in β‐sheet content and a decrease in β‐turn (β‐spiral) content. However, this bran‐induced transconformational change in gluten was more significant in the 2137 flour dough than in Overley flour dough. This study revealed that when bran is added to flour dough, water redistribution among dough components promotes partial dehydration of gluten and collapse of β‐spirals into β‐sheet structures. This transconformational change may be the physical basis for the poor quality of bread containing added bran.     

哀牢山亚热带次生林AM真菌的初步研究*

 哀牢山分布着目前我国面积最大、保存最完整的亚热带山地湿性常绿阔叶林。为摸清该地的丛枝菌根真菌群落结构和多样性现状，采用碱离解-锥虫兰染色法和湿筛法，对哀牢山亚热带次生林中丛枝菌根真菌的侵染率（colonization level）、孢子密度（Spore density）、物种丰富度（species richness）、频度（species frequency）及AMF的结构类型进行了研究。从5个样点不同植物的根围土壤中分离到了隶属于球囊霉属（Glomus）、巨孢囊霉属 （Gigaspora）、盾巨孢囊霉属（Scutellospora）和无梗囊霉属（Acaulospora）的8种AM真菌。该地AMF侵染率为23.0%～89.0%；孢子密度为每100 g土壤27～42个；物种丰富度为2～6；在受侵染的植物中，82%的植物的AMF结构类型为Arum型，而Paris型只占18%；球囊霉属（Glomus）和巨孢囊霉属（Gigaspora）的AM真菌是哀牢山亚热带次生林中出现频率较高的丛枝菌根真菌类群。