Milk fat is one of the complex fat and most sensitive biochemical compounds towards auto-oxidation. To enhance the shelf life, milk is subjected to Ultra-high Temperature (UHT) treatment followed by aseptic packaging. During the storage, several chemical and biochemical changes take place in lipid fraction of UHT milk. In current investigation, the effect of UHT treatment and storage was determined by making a comparison in fatty acid profile, triglyceride composition, organic acids and lipid oxidation of the thermally treated and stored milk with raw milk, which was not reported in earlier investigations. Raw milk samples were collected from the bulk storage facility of a dairy industry. The same milk was routed to UHT treatment and aseptically packaged samples were collected. The fatty acid profile, triglyceride composition, organic acids and lipid oxidation was determined in raw and UHT treated milk at 0, 30, 60 and 90 days. Fatty acid and triglyceride profile was determined on GC-MS while organic acids were determined by HPLC. For the measurement of induction period, professional Rancimat was used. Lipid oxidation was characterized through free fatty acids, peroxide value, anisidine value and conjugated dienes. Compositional attributes of milk remain unchanged during the entire length of storage. Concentrations of short-chain fatty acids in raw and UHT milk were 10.49% and 9.62%. UHT treatment resulted in 8.3% loss of short-chain fatty acids. Up to 30 days, storage did not have any significant effect on fatty acid profile of UHT milk. Concentration of medium-chain fatty acids in raw and UHT treated milk was 54.98% and 51.87%. After 30, 60 and 90 days of storage, concentration of medium chain fatty acids was found 51.23%, 47.23% and 42.82%, respectively. Concentration of C18:1 and C18:2 in raw and UHT milk was 26.86% and 25.43%, respectively. The loss of C18:1 and C18:2 in UHT treatment was 5.32%. After 30, 60 and 90 days of storage, the concentrations of C18:1 and C18:2 were 24.6%, 21.06% and 18.66%, respectively. Storage period of 30 days was found non-significant, while noticeable variations were found in triglyceride profile of 60 and 90 days old samples of UHT milk. UHT treatment and storage period significantly affected the concentration of organic acids in milk. After UHT treatment, concentration of lactic acid, acetic acid, citric acid, pyruvic acid, formic acid, succinic acid and oxalic acid increased by 3.45, 0.66, 3.57, 0.68, 2.24, 2.16 and 1.63 mg/100 g. Effect of storage period on the production of organic acids in UHT milk was non-significant up to 30 days. After 60 days of storage period, the increase in concentration of lactic acid, acetic acid, citric acid, pyruvic acid, formic acid, succinic acid and oxalic acid was 3.79, 0.75, 4.69, 0.78, 2.83, 3.03 and 2.38 mg/100 g. After 90 days of storage period, the increase in concentration of lactic acid, acetic acid, citric acid, pyruvic acid, formic acid, succinic acid and oxalic acid was 7.3, 2.18, 9.96, 3.58, 11.37, 5.22 and 5.96%. Free fatty acids content of raw, UHT treated and 90 days old milk were 0.08%, 0.11% and 0.19%. UHT treated version of milk showed similar peroxide value. While, the storage remarkably affected the peroxide value. After 30, 60 and 90 days, peroxide value was 0.42, 0.62 and 1.18 (MeqO2/kg). Induction period of raw, UHT and stored milk was strongly correlated with peroxide value and fatty acid profile. Mean value of lipase activity in raw milk was 0.73 ± 0.06 μmoles/ml. UHT treatment significantly decreased the lipase activity. The lipase activity of milk immediately after the UHT treatment was 0.18 ± 0.02 μmoles/ml. Lipase activity of UHT milk after 30, 60 and 90 days of room temperature storage was 0.44 ± 0.03, 0.95 ± 0.07 and 1.14 ± 0.09 μmoles/ml. Color, flavor and smell score decreased through the storage of UHT milk for 90 days. The results of this investigation revealed that fatty acid and triglyceride profile changed after 60 and 90 days of storage. Production of organic acids led to the drop of pH and sensory characteristics in UHT milk during the long-term storage. Induction period can be successfully used for the determination of anticipatory shelf life of UHT milk.

Chia (Salvia hispanica L.) is known as power house of omega fatty acids which has great health benefits. It contains up to 78% linolenic acid (ω-3) and 18% linoleic acid (ω-6), which could be a great source of omega-3 fatty acids for functional foods. Therefore, in this study, margarines were prepared with supplementation of different concentrations of chia oil to enhance omega-3 fatty acids, antioxidant characteristics and oxidative stability of the product. Margarines were formulated from non-hydrogenated palm oil, palm kernel and butter. Margarines were supplemented with 5, 10, 15 and 20% chia oil (T1, T2, T3 and T4), respectively. Margarine without any addition of chia oil was kept as control. Margarine samples were stored at 5 °C for a period of 90 days. Physico-chemical (fat, moisture, refractive index, melting point, solid fat index, fatty acids profile, total phenolic contents, DPPH free radical scavenging activity, free fatty acids and peroxide value) and sensory characteristics were studied at the interval of 45 days. The melting point of T1, T2, T3 and T4 developed in current investigation were 34.2, 33.8, 33.1 and 32.5 °C, respectively. The solid fat index of control, T1, T2, T3 and T4 were 47.21, 22.71, 20.33, 18.12 and 16.58%, respectively. The α-linolenic acid contents in T1, T2, T3 and T4 were found 2.92, 5.85, 9.22, 12.29%, respectively. The concentration of eicosanoic acid in T2, T3 and T4 was 1.82, 3.52, 6.43 and 9.81%, respectively. The content of docosahexanoic acid in T2, T3 and T4 was present 1.26, 2.64, 3.49 and 5.19%, respectively. The omega-3 fatty acids were not detected in the control sample. Total phenolic contents of control, T1, T2, T3 and T4 samples were 0.27, 2.22, 4.15, 7.23 and 11.42 mg GAE/mL, respectively. DPPH free radical scavenging activity for control, T1, T2, T3 and T4 was noted 65.8, 5.37, 17.82, 24.95, 45.42 and 62.8%, respectively. Chlorogenic acid, caffeic acid, quercetin, phenolic glycoside k and phenolic glycoside Q in T3 were present 0.78, 0.73, 1.82, 4.12 and 4.49 mg/mL, respectively. After 90 days of storage period, free fatty acids and peroxide value of all the treatments were less than 0.2 (% and MeqO2/kg). Sensory characteristics of treatments were not different from the control. Margarines supplemented with chia oil showed enhanced level of omega-3 fatty acids and antioxidant characteristics. These results suggest that chia oil can be used for formulation of margarine with increased level of omega-3 fatty acids and acceptable sensory characteristics.

Yogurt is defined as a coagulated milk product obtained from the fermentation of lactose into lactic acid. Drinking yogurt (laban) was prepared from buffalo milk, cow milk, and a 50:50 blend (cow + buffalo milks) by adding 0.5% carboxymethyl cellulose to each of the 3 milk treatments. Samples were then refrigerated for 7, 14, and 21 d before determination of physical, microbial, and sensory parameters. Yogurt prepared from buffalo milk had higher fat and protein contents, and better taste, aroma, and overall consumer acceptability compared with laban prepared from cow milk or mixed milk. During storage, protein and total solids contents remained unchanged, whereas milk fat, color, appearance, taste, smell, texture, and overall acceptability of laban decreased in the different treatment groups. The acidity of laban increased with storage time. Bacteria, including coliforms, were not found in any treatment group during storage. In conclusion, overall acceptability of laban prepared from buffalo milk was higher than that made from cow milk or mixed milk, but increased storage time reduced the quality of laban prepared from cow, buffalo, or mixed milk.

Cream cheese analogue is a soft cheese with a slightly sweet and pleasantly tangy taste. It is prepared using the substitutes of dairy fats and proteins partially or completely. Cream cheese analogue ingredients are purchased carefully keeping in mind the required specifications. For the above-mentioned research, different samples of cream cheese (T0, T1, T2 and T3) were manufactured with standardized fat and protein and the moisture was maintained at 50–55% during these trials. All ingredients were added in a large container for mixing and cooking treatment for 1–2 min at 75 °C and homogenized for 5–6 min with the help of a hand mixture until completely homogenous sample was obtained. Samples were then transferred in to another container and allowed them to attain temperature between 20 and 25 °C. After that, samples were incubated with the addition of mesophilic culture until desired pH (4.6–4.7) was achieved. Later samples were heated at 50–55 °C for 2–3 min and then placed in a muslin cloth and left overnight for whey drainage. Physicochemical, microbial analysis were performed while sensory evaluation was performed using different parameters and scales. Sample prepared using 75% dairy cream and 25% cocoa butter substitute fat (T1) showed good results. T1 had better consistency which was considered desirable characteristics of cream cheese. This research proved the cost effective as cream cheese prepared with plant-based fat which made its production possible at industrial level. Cream cheese which was made from dairy fat (75%) and cocoa butter substitute fat (25%) had more springiness, smoothness, gumminess, more pleasant taste, color, flavor and aroma than other samples. This dairy product can be used in future in Pakistan.

The present study analyses the effect of storage time and varying fat levels in fermented laban milk samples obtained from different sources through physicochemical, sensory and microbiological attributes. The milk samples were divided into three groups (T1 = Buffalo Milk, T2 = Cow Milk, T3 = Mixed Milk) with replication. Viscosity, acidity and syneresis of all three laban milk samples increased, whereas pH decreased significantly (P ≤ .05) across storage days. The viscosity, protein and total solids (TS) were significantly (P ≤ .05) decreased in all Laban milk samples with a 3.5% fat level compared to a 1.5% fat level at the 21st day of the storage period. The colour and appearance scores were unaffected for the T1 group but decreased with increased fat levels for T2 and T3 groups. The Total Plate Count tended to decrease with a 3.5% fat level in all three laban milk samples. However, days of storage had a non-significant effect. Buffalo laban milk seems best in terms of viscosity, protein, TS, taste and aroma. Furthermore, these attributes are affected by days of storage and fat level. The fermented laban prepared from mixed milk (T3) showed results at par with that from buffalo milk. Hence, considering the economical aspect, mixed milk laban at a fat level of 3.5% is highly recommended.