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This review summarizes the recent developments in understanding of the relationships between the diet of animals and the sensory quality of dairy products. Feeding dairy cattle with maize silage by comparison with hay or grass silage leads to whiter and firmer cheeses and butter and sometimes to differences in flavour. Major differences in sensory characteristics were observed between cheeses made with milk produced by cows on winter diets (based on hay and grass silage) or turned out to pasture in the spring. Conversely, preserving grass as silage, by comparison with hay, has no major effect on cheese sensory characteristics, except on colour, the cheese being yellower with grass silage. Several recent experiments have shown a significant effect of grass botanical composition on cheese texture and flavour. These effects are due to the presence in milk of specific molecules directly introduced by feeding (carotenes, terpenes) or produced by the animals (plasmin, fatty acids) under the effect of specific diets.

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-The influence of pastures on milk characteristics was studied in natura in the Abondance cheese area (Haute-Savoie, France) on 10 diversified pastures exploited by 3 dairy farmers. The effects of the herd were controlled and measured by feeding an identical hay to herds. The plasmin activity and the concentration of long-chain poly-unsaturated fatty acids in milks produced in mountain pastures (n = 5, 1 500 and 1 850 m) were significantly higher (P < 0.001 and P < 0.05 respectively) than in milks from valley pastures (n = 5, 850 and 1 100 m). The terpene composition of milk was linked to the terpene composition of pastures. Milks from the pastures rich in dicotyledons, in particular Apiaceae, contained a greater quantity and a wider variety of terpenes, than milks from the pastures rich in Gramineae. The other volatile compounds, casein composition, calcium and phosphorus contents did not seem to be influenced by the type of pasture.pasture / milk / plasmin / fatty acid composition / volatile compound Résumé -Influence de la nature de pâturages alpins sur l'activité de la plasmine, la composition en acides gras et en composés volatils du lait. L'influence de la nature des pâturages sur les caractéristiques des laits a été étudiée in natura dans la zone du fromage d'Abondance (Haute-Savoie, France) sur 10 types de pâturages divers exploités par 3 producteurs. Les effets liés au troupeau ont été contrôlés et mesurés sur une période où les 3 troupeaux recevaient la même alimentation. L'activité de la plasmine et la teneur en acides gras poly-insaturés à 18 carbones étaient plus élevées dans les laits des pâturages de montagne (n = 5, 1 500-1 850 m) que celles des laits de pâturages de vallée (n = 5, 850-1100 m) (respectivement P < 0,001, P < 0,05). La composition en terpènes des laits est apparue dépendre de celle des pâturages. Les laits issus des pâturages les plus riches en dicotylédo-nes, notamment en ombellifères, contenaient plus de terpènes, tant en quantité qu'en variété, que les laits issus des pâturages riches en graminées. Les compositions en molécules volatiles non terpéni-ques et en caséines, les teneurs en calcium et phosphore n'ont pas semblé être influencées par le type de pâturage.pâturage / lait / plasmine / composition en acides gras / composé volatil

A study was undertaken to compare the chemical and sensory characteristics of Abondance cheeses made with milk from animals grazing areas within the same highland pasture, but with different predominant plants. Nine cheeses made during the last 3 d of three successive 7 d periods were evaluated. The animals grazed on the southern side of the highland pasture during the first period (15–21 June), on the northern side during the second period (22–29 June) and returned to the southern side for the third period (30 June–6 July). The gross composition of the cheeses did not vary between periods. ‘North’ cheeses contained more plasmin, γ-casein, αs1-I-casein and water-soluble N than ‘south’ cheeses. Both sensory and instrumental measurements indicated that north cheeses were less firm, stickier and more easily fractured than south cheeses. North cheeses were also more salty, bitter and persistent. Their overall aroma was more intense and they had more intense sour, burnt, toasted, fermented vegetable and sweat aromas, but less intense toffee, exotic fruit and acid milk aromas. The texture differences noted between the cheeses from milk produced on the two areas may come from differences in primary proteolysis, partly due to different amounts of plasmin and plasminogen in milk and in cheeses. The aroma differences were related to differences in volatile compounds. Some compounds had a microbial origin, while some others may have come from the pasture.