A kit for producing a personalized, concentrated human milk composition for an infant, the kit comprising: at least one analyzer for determining a concentration of at least one nutrient and/or at least one micronutrient present in the expressed breast milk from the mother; at least one selective concentration device capable of concentrating at least one nutrient and/or at least one micronutrient present in expressed breast milk from a mother of the infant and wherein the selective concentration device is a selective ultrafiltration device; at least one graduated container capable of receiving the expressed breast milk and capable of measuring a volume of the expressed breast milk, the at least one graduated container being capable of association with the selective concentration device for concentration of the breast milk disposed therein to produce the personalized, concentrated human milk composition; and at least one device that calculates a desired level of concentration of the breast milk based upon a concentration of at least one nutrient and/or at least one micronutrient present in the expressed breast milk and at least one infant factor selected from the group consisting of the infant's height, the infant's weight, the infant's nutritional needs, the infant's fluid volume capacity, the infant's growth curve, and combinations thereof and wherein the device calculates a desired level of concentration of the breast milk based upon a concentration of each of a plurality of nutrients and/or micronutrients present in the expressed breast milk and a plurality of infant factors, and wherein the calculated level of concentration is defined as: (i) a desired concentration of one or more of the plurality of nutrients and/or micronutrients; and/or (ii) a desired ratio of two of the nutrients/micronutrients to one another. at least one analyzer for determining a concentration of at least one nutrient and/or at least one micronutrient present in the expressed breast milk from the mother; at least one selective concentration device capable of concentrating at least one nutrient and/or at least one micronutrient present in expressed breast milk from a mother of the infant and wherein the selective concentration device is a selective ultrafiltration device; at least one graduated container capable of receiving the expressed breast milk and capable of measuring a volume of the expressed breast milk, the at least one graduated container being capable of association with the selective concentration device for concentration of the breast milk disposed therein to produce the personalized, concentrated human milk composition; and at least one device that calculates a desired level of concentration of the breast milk based upon a concentration of at least one nutrient and/or at least one micronutrient present in the expressed breast milk and at least one infant factor selected from the group consisting of the infant's height, the infant's weight, the infant's nutritional needs, the infant's fluid volume capacity, the infant's growth curve, and combinations thereof and wherein the device calculates a desired level of concentration of the breast milk based upon a concentration of each of a plurality of nutrients and/or micronutrients present in the expressed breast milk and a plurality of infant factors, and wherein the calculated level of concentration is defined as: (i) a desired concentration of one or more of the plurality of nutrients and/or micronutrients; and/or (ii) a desired ratio of two of the nutrients/micronutrients to one another. (i) a desired concentration of one or more of the plurality of nutrients and/or micronutrients; and/or (ii) a desired ratio of two of the nutrients/micronutrients to one another. <EOS>