Peter C. Quantick

Changes in phenolic compounds in Litchi (Litchi chinensis Sonn.) fruit during postharvest storage

Abstract Litchi (Litchi chinensis Sonn. cv. Huaizhi) fruit were stored at ambient temperature (20–25°C) for up to 7 days and at 4°C for up to 35 days for separation, purification and identification of individual phenolic compounds and investigation of their changes during postharvest storage. Results indicate that flavan-3-ol monomers and dimers were major phenolic compounds representing about 87.0% of the phenolic compounds that declined with storage or browning. Cyanidin-3-glucoside was a major anthocyanin and represented 91.9% of anthocyanins. It also declined with storage or browning. Small amounts of malvidin-3-glucoside were also found. Therefore, the major substrates for enzymatic oxidation were apparently flavan-3-ol monomers and dimers and cyanidin-3-glucoside.

Smell perception during early pregnancy : no evidence of an adaptive mechanism

Objective  It has been suggested that nausea and vomiting in pregnancy is an evolutionary adaptive mechanism to avoid the ingestion of potentially harmful foods. It has also been suggested that the mechanism that triggers nausea and vomiting in pregnancy may be olfaction and that olfactory senses are invoked to provide this protection. This study aimed to test this theory in a systematic design.

A comparative study of effects of nitrogen and argon on tyrosinase and malic dehydrogenase activities

Tyrosinase and malic dehydrogenase were treated with argon and nitrogen. Their activities were measured with time. The activities of tyrosinase and malic dehydrogenase when treated directly with argon, and when treated as a mixture of the enzymes and their substrates, were lower than with nitrogen treatments. The results suggest that argon reduces the activities of tyrosinase and malic dehydrogenase more than nitrogen. Tyrosinase activity with argon treatment was reduced by up to 14.2% more than nitrogen treatment when treated directly, and by up to 22.6% in the mixture of the enzyme and substrate. Malic dehydrogenase activity with argon treatment was reduced by up to 9.5% more than nitrogen treatment when treating the enzyme directly, and by up to 13.9% in the mixture of the enzyme and substrate.

Food and Health Applications of Marine Nutraceuticals: a Review

With the growing public awareness of the nutritional, diet and health benefits of Seafoods, the stage is now to set for the development of mainstream nutraceutical products. Application of marine-based nutraceuticals includes fish oil (mainly omega-3 polyunsaturated fatty acids), seal blubber oil, algal oil, shark liver oil and squalene, shark cartilage, chitin, chitosan as well as their monomers and oligomers, enzymes, peptides and related compounds, vitamins (A, particularly its precursor β-carotene, D and E), seaweed (macroalgae) and its components, protein hydrolysates and other products has become a topic of great interest for both pharmaceutical and health food industries. This review provides an account of marine nutraceuticals and their application. Where available, the health benefits of nutraceuticals of interest are also discussed.

Changes in the levels of histamine during processing and storage of fish meal

Abstract Processing and storage trials were carried out under controlled laboratory conditions to investigate the effect of processing and storage conditions on histamine formation during fish meal production. It was found that most histamine concentrated in the press liquor (stickwater) meal after processing. Histamine levels were mainly decreased in mackerel samples but increased in cod samples after processing into fish meal. Histamine was detected in the fish meal samples of fish offal of both cod and mackerel. No bacterial growth was observed in the press-cake when fish was cooked and pressed during fish meal production. After drying of solids and the stickwater, bacterial growth was observed. This is an indication that fish meal is apparently microbiologically hygienic after cooking process, then recontamination occurs. That samples were packed in polyethylene bags seemed to show a slight increase in histamine levels up to fifth week but a significant decrease (P

Effect of Cooking on Consumers Perceptions of Mackerel (Scomber Scombrus) of Poor Quality

Wrapped and unwrapped raw mackerel samples, stored chilled (Chilled mackerel) and frozen then chilled (FC mackerel), were monitored for histamine content and assessed by sensory means over 3 days of storage. A score of about 20 coincided with the level at which fish were considered unacceptable by members of the panel. All samples showed good quality up to day 3 except unwrapped FC mackerel which showed fair quality. Cooked mackerel samples were also assessed during the same period for flavor, odor, texture and overall opinion about the effect of cooking on overall aroma quality. All samples showed normal flavor characteristics of good quality fish during storage. Although highly significant differences (P 0.05) were observed between the trials when the cooked mackerel samples were used. This indicated that cooking would appear to have masked any undesirable changes observed in fish, provided these changes were not extreme. Further investigation showed that cooking resulted in increases in the quantity of aldehydes detected. This might be crucial for overall aroma quality by masking some of the undesirable aroma changes in fish