Development of Free Radical Products during the Greening Reaction of Caffeic Acid Esters (or Chlorogenic Acid) and a Primary Amino Compound
ESR spectra were measured directly on a marked greening reaction mixture of Et-caffeate and a primary amino compound in alkali solution under aeration. A clear hyperfine structure was commonly detected early in the greening reaction with different amino compounds. Its hyperfine spectrum split into seven peaks was analyzed and found to be due to the oxidized free radical product of the Et-caffeate using an authentic sample system. Another type of hyperfine ESR spectrum was observed later in the reaction, and was altered with different amino compounds. The hyperfine structure for n-butylamine split into 12 lines. The latter type of free radical products were assumed to be a semiquinone type radical compounds of the trihydroxy benzacridine derivative, which was identified as the principal structure of the green and yellow pigments formed by this greening reaction system. A formation mechanism of the green pigment and related products involving these free radical products is proposed.
Fatty acids, essential amino acids, and chlorogenic acids profiles, in vitro protein digestibility and antioxidant activity of food products containing green coffee extract.
The aim of this study was to determine the effect of addition of green coffee extract (GCE) in concentrations from 0.25 to 1 g 100 g-1 on the physical, sensory and chemical properties, and antioxidant activity of some food products. Two kinds of gnocchi (from fresh and dried potatoes), sponge cake, bread, mayonnaise, marshmallows, caramel candies and jellies were prepared. Among supplemented products food with the maximal GCE addition best sensory properties showed mayonnaise, followed by marshmallows and jellies. Addition of GCE caused changes in color of products, where the smallest changes were observed in mayonnaise and gnocchi from dried potatoes (ΔE 1.20 and 2.93 respectively) and the highest in jellies and sponge cake (ΔE 20.38 and 12.80 respectively). GCE added to food products allowed to maintain higher amount of polyunsaturated fatty acids (PUFA), especially prepared with the use of high temperature, such as marshmallows. In this product with 1 g 100 g-1 of GCE the PUFA content was 5.82 g 100 g-1 while in control it amounted 4.55 g 100 g-1. The losses of polyphenol introduced to the food products with GCE were the smallest in mayonnaise and jellies prepared under low temperature. Addition of GCE contributed to the increase of antioxidant activity of enriched products. The highest increase of antioxidant activity was observed in sponge cake, followed by candies, marshmallows and mayonnaise. The losses of amino acids caused by the addition of GCE were greatest in products treated at a moderately high temperature and subject to further gelation, i.e. jellies and marshmallows. Despite higher losses of amino acids the effect of the addition of GCE on protein pepsin digestibility the did not exceed 3%.
Microbial flora of frozen tail meat from captive Nile crocodiles (Crocodylus niloticus).
Frozen tail meat samples from nine Nile crocodiles (Crocodylus niloticus) were evaluated for microbial numbers and types. Microbial analyses yielded a mean aerobic plate count (APC, 30 degrees C) of 4.86 log cfu/g, a mean coliform count (TC, 37 degrees C) of 3.77 log cfu/g and a mean faecal coliform count (FC, 44 degrees C) of 3.40 log cfu/g. Salmonella was isolated from three samples, and beta-haemolytic streptococci from two samples. Yersinia, Aeromonas, Staphylococcus aureus and Bacillus cereus were not isolated. Typical bacterial genera recovered included Flavobacterium, Pseudomonas, Acinetobacter, Enterobacter, Moraxella, Micrococcus, Staphylococcus and Streptococcus.