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IN-PLANT PILOT STUDY
The objectives of the study were:
1. To use CoaguSens™ Connect to measure curd firmness during coagulation and specifically at exact cutting time.
2. To stabilize the variability of cheddar cheese yield by stabilizing the firmness at curd cutting time.
The study has been divided into two phases:
PHASE I – LEARNING PHASE
The objectives in this phase were:
— To measure the firmness of milk gels during coagulation for different vats.
— To determine the mean value of firmness at cutting time as controlled by cheesemakers.
In Phase I, cutting time was determined according to the cheesemakers’ manual evaluation of milk gel texture and appearance while simultaneously monitoring the milk gel firmness during coagulation using CoaguSens™ Connect. Coagulation kinetics were recorded for different batches during 4 weeks and the mean values and standard deviations of milk gel firmness at cutting step and cutting times were analyzed.
PHASE II – INITIATING CUTTING BASED ON CURD FIRMNESS
The objectives in this phase were:
— To cut the curd when firmness reaches the mean value determined in Phase I.
— To collect data on yield and measure the impact of a better control of cutting firmness on the variability of cheese yield.
In Phase II, the milk gel formation was measured using CoaguSens™ Connect as in Phase I, but now the gel was cut when it reached the mean elasticity obtained in Phase I.
Milk composition (fat, protein and total solids content) was determined using MilkoScan FT2 Infrared Milk Analyzer (FOSS, Denmark). Seasonal variation in milk composition was observed between phases I (February) and II (March-April) as shown in Table 1. Because milk in phase II was less rich than in phase I, it was anticipated that yield decreases in phase II.
Seasonal variation in milk composition between phases I (February) and II (March-April)
Fig. 1 Mean values and variability of cutting time (above) and cutting firmness (below) in Phase I (blue) and Phase II (red), without and with CoaguSens™ Conncect, respectively.
In Phase II, the cutting of curd was started when the firmness reached the mean value measured in Phase I. This led to greater variability (+ 51 %) in cutting times due to batch-to-batch variation of coagulation kinetics, but reduced the variability in cutting firmness by -51 % (Fig. 1).
Importantly, the effect of reduced variability in milk gel firmness at cutting was observed in cheese yield: the variability in actual yield decreased from ± 0.47 % to ± 0.25 %, that is, by 45 % (Fig. 2). The mean yield in Phase II remained stable compared to Phase I because the mean cutting firmness was identical in both phases. In addition, the use of CoaguSens™ Connect to monitor the cutting time prevented the expected decrease of yield because of the change in milk composition between phases I and II.
The use of CoaguSens™ Connect had also an impact on the variability of cheese moisture. Moisture variability of white cheddar decreased by 28 %.
CoaguSens™ Connect is a new automation instrument for the at-line monitoring of coagulation processes and the determination of cutting time based on the firmness of the milk gel. The results of this study performed in a medium-size cheese plant showed reduced variability in yield after stabilizing the firmness at which the curd is cut. This allows refining the process and leads to considerable savings upon improved quality and enhanced process efficiency. Rapid, simple and quantitative measurement of curd firmness using CoaguSens™ Connect facilitates further automation of the cutting step.
Fig. 2 Cheese yield (actual yield) and its variability in phases I (without CoaguSens™ Connect) and II (with CoaguSens™Connect)
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