Changes in purine and uric acid content in edible insects during culinary processing.

Recently, edible insects were proposed to be promising alternative foods combining nutritional, environmental, and economic benefits. While composition of the basic nutrients of insects is quite well known, little is known about other compounds contained in them such as purines. From this point of view, raw insects were reported to belong among purine-rich foods. However, they are generally consumed after culinary processing, which is known to affect nutritional composition of foods. Therefore, we aimed to analyze the effect of culinary processing (including various combinations of boiling, roasting, blanching, baking, and oven drying) on purine (adenine, guanine, xanthine, and hypoxanthine) contents and their metabolite (uric acid) in three insects (Tenebrio molitor, Gryllus assimilis, and Acheta domesticus) fit for human consumption using RP-HPLC with UV detection. According to obtained data, boiling for 15 min significantly reduced the purine content in T. molitor but did not affect the purine levels in A. domesticus and G. assimilis. In contrast, the purine content increased in all insects after baking (especially at 220 °C). The information this study provides can help people suffering from gout interested in entomophagy to choose the best culinary treatment of insects to help prevent gout symptoms.

Feed Insects as a Reservoir of Granadaene-Producing Lactococci.

Insects are a component of the diet of different animal species and have been suggested as the major source of human dietary protein for the future. However, insects are also carriers of potentially pathogenic microbes that constitute a risk to food and feed safety. In this study, we reported the occurrence of a hemolytic orange pigmented producing phenotype of Lactococcus garvieae/petauri/formosensis in the fecal microbiota of golden lion tamarins (Leontopithecus rosalia) and feed larvae (Zophobas atratus). Feed insects were identified as a regular source of L. garvieae/petauri/formosensis based on a reanalysis of available 16S rRNA gene libraries. Pan-genome analysis suggested the existence of four clusters within the L. garvieae/petauri/formosensis group. The presence of cyl cluster indicated that some strains of the L. garvieae/petauri/formosensis group produced a pigment similar to granadaene, an orange cytotoxic lipid produced by group B streptococci, including Streptococcus agalactiae. Pigment production by L. garvieae/petauri/formosensis strains was dependent on the presence of the fermentable sugars, with no pigment being observed at pH <4.7. The addition of buffering compounds or arginine, which can be metabolized to ammonium, restored pigment formation. In addition, pigment formation might be related to the source of peptone. These data suggest that edible insects are a possible source of granadaene-producing lactococci, which can be considered a pathogenic risk with zoonotic potential.

Formation of oxysterols during thermal processing and frozen storage of cooked minced meat.

BACKGROUND: Cholesterol is susceptible to oxidation and the formation of oxysterols, which could have a negative health effect. The formation and distribution of oxysterols was investigated in meatloaves prepared under different baking regimes with an increased temperature or prolonged time. The effect of frozen storage and marjoram addition on the level of oxysterols was also investigated. RESULTS: The effect of baking regime on the content and distribution of oxysterols was determined. Temperature was the most important factor affecting 7-ketocholesterol formation in baked meatloaf. Its content was significantly higher after baking at 250 °C compared to at 180 °C. The content of 7-ketocholesterol increased from the centre (87 µg kg-1 ) to the surface (122 µg kg-1 ) of baked meatloaves prepared under standard conditions. The level of α-tocopherol and its distribution was also affected by the baking regime. A higher level of 7-ketocholesterol was found in baked meatloaves after their frozen storage. The addition of marjoram did not change this level. CONCLUSION: Inadequate culinary conditions used for preparation of baked meat can contribute to an increased oxysterol intake in the diet. Frozen storage did not stop oxysterol formation. The inhibition effect of marjoram on sterols oxidation was not confirmed. © 2017 Society of Chemical Industry.