Loretta Gambelli

Nutrients in edible mushrooms: an inter-species comparative study

A comparative study on various components of nutritional interest, such as water, protein, total amino acids, ash and minerals, in mushrooms of different species (Pleurotus ostreatus, Pleurotus eryngii, Pleurotus pulmunarius and Lentinula edodes) was carried out. Mushrooms were cultivated on the same compost (wheat straw added with 15% of sugar beet) and analysed immediately after harvest to avoid any interfering parameters. The limiting amino acid was also evaluated and the relevant protein chemical score was calculated. The moisture content of the edible mushrooms studied is high (ranging from 85.2 to 94.7%) and the ash contents range from 6.9 to 10.5% on a dry basis. Potassium is the most abundant mineral element followed by magnesium. Total nitrogen varies from 3.47 to 7.93% (dry basis), and P. ostreatus species has the largest variability among the samples analysed. The most abundant amino acids in mushrooms, expressed as percentages of total amino acids, are glutamic acid (12.8–20.9%), aspartic acid (9.1–12.1%) and arginine (3.7–11.7%), but in the analysed P. pulmunarius and L. entinus edodes a particularly low percentage of arginine (3.7 and 5.7%) has been detected. The chemical score generally ranges from 96 to 110%, the limiting amino acid being leucine or/and lysine. ©

New trends in the seafood market. Sutchi catfish (Pangasius hypophthalmus) fillets from Vietnam: Nutritional quality and safety aspects

Sutchi catfish (Pangasius hypophthalmus) produced in the freshwater basins of Vietnam, available on the Italian market as frozen or thawed fillets, were studied for their nutritional quality and safety aspects. Proximate composition, mineral content, fatty acid profile, unsaponifiable components of the lipid fraction and drip loss during thawing at 5°C were determined on the fillets. Fillets were characterised by high moisture levels (80-85%) and low protein (12.6-15.6%) and lipid (1.1-3.0%) contents. Total lipids were characterised by low cholesterol levels (21-39mg/100g), high percentages of saturated fatty acids (41.1-47.8% of total fatty acid) and low percentages of polyunsaturated fatty acids (12.5-18.8% of total fatty acids), which were mainly represented by linoleic acid (44-59% of total polyunsaturated fatty acids). The mineral composition was characterised by a high sodium content (222-594mg/100g), probably partially due to the sodium tripolyphosphate (E 451) used to retain moisture. As regards safety aspects, the quality of the samples analysed was good, with low residue levels of mercury, organochlorine pesticides and polychlorinated biphenyls.

Quality characteristics of sharpsnout sea bream (Diplodus puntazzo) from different intensive rearing systems.

An experimental investigation was carried out on sharpsnout sea bream (Diplodus puntazzo) reared in cage and in tank to evaluate the influence of the different culturing conditions on the nutritional quality of the fish. Fillets from fish of the same genetic origin and size, reared separately in tank and in cage, were analysed for proximate composition, inorganic elements, unsaponifiable lipid fraction compounds, fatty acid profiles of total, neutral and polar lipids and for textural properties. The proximate composition of differently-reared fish did not differ significantly except for the greater lipid content of the tank-reared specimens. High performance liquid chromatography of unsaponifiable lipids showed significantly higher levels of squalene, cholesterol and all-trans retinol in tank-reared fish fillets. Gas chromatography of total, neutral and polar lipids showed few differences between the fatty acid profiles of tank- and cage-reared fish. Firmness and amount of expressed liquid were also influenced by the rearing techniques.

Constituents of nutritional relevance in fermented milk products commercialised in Italy

Fermented milk products represent an increasing share of the dairy products consumed in Italy. The nutritional value of these products is related to the milk utilised and to the eventual presence of other ingredients (milk powder, sugar, fruit puree and fruit extracts), whereas the microrganisms used can affect texture and organoleptic characteristics. In this paper constituents of nutritional relevance such as protein, fat, total carbohydrate, amino acids, minerals, vitamin A, vitamin E and cholesterol, have been evaluated in yoghurts, fermented milks (plain and with essences) and Quark cheeses (plain and with fruits). This study confirms the high nutritional quality of fermented milks and stresses the role of non-milk ingredients in modifying and, sometimes, improving the dietary contribution of these products.