Survival Analysis Applied to Sensory Shelf Life of Foods

Multivariate Nature of Fish Freshness Evaluation by Consumers

The aim of the present study was to evaluate the sensory acceptability limit of refrigerated fish through a multivariate approach, involving classic physicochemical and bacteriological indicators and considering different consumer profiles. The results of the survival analysis demonstrated that, in general, consumers still considered the fish to be suitable for purchase (4.128 days of storage), despite being microbiologically unsuitable for consumption. However, the subsequent division of consumers into clusters indicated that women and individuals with high income and education levels tend to reject fish with few days of storage (3.650 days), mainly due to discoloration, despite still being microbiologically suitable for consumption. Thus, these segments present a safer behavior regarding the purchase of fresh fish. The influence of different frequencies of fish consumption and age of consumers on the assessment of fish freshness was not clarified. The responsibility for ensuring safe and healthy products at the point of sale must lie with the producers and distributors. However, improving consumers’ ability to make good choices when buying fresh fish would bring social and economic benefits related to public health and to the seafood industry, because it would enable them to make relevant claims and demand their rights.

Evaluating Freshness Loss of Green Tea with Q10 Method and Weibull Hazard Analysis under Accelerated Shelf Life Testing

The important quality of green tea is freshness, but high temperature, light, oxygen, and humidity during storage may reduce the freshness of green tea. Thus, this study investigated the freshness loss of green tea (FLGT) under an accelerated shelf-life testing (ASLT) by sensory evaluation and acceptability test. The FLGTs of the samples stored at 20°C, 30°C, and 40°C, were determined as 67 days, 55 days, and 45 days, respectively by the Q10 method. In addition, they were further determined as 67 days, 57 days, and 42 days, respectively, by the Weibull Hazard Analysis (WHA). The sensory evaluation and acceptability test confirmed the correctness of the above results by 2-alternative choice analysis and chemical analysis. The Q10 method was applied to predict the FLGTs stored at 4°C and −20°C which were 93 days and 150 days, which was further verified by 2-alternative choice analysis and chemical analysis. The results show that it is possible to predict the suitable drinking period of green tea during storage by the Q10 method.

Chocolate as Carrier to Deliver Bioactive Ingredients: Current Advances and Future Perspectives

Consumer demand for healthier foods with improved taste and convenience has urged the food industry to develop functional foods added with bioactive ingredients that can supplement basic nutrition (food supplement) or exert a pharmacological effect (nutraceuticals). Chocolate could be used as an ideal carrier to deliver bioactive ingredients, mainly due to its high acceptability by consumers. However, a drawback of using chocolate as functional food is its high sugar content, which impedes its commercialization with the diabetic population. Therefore, there is need to develop sugar-free chocolate formulations added with bioactive ingredients. Nevertheless, sugar replacement and bioactive ingredients addition is a major technological challenge that affects texture, rheology, and sensory properties of chocolate. This review is designed as a practical guide for researchers and food industries to develop the next generation of functional chocolates. Different functional chocolate formulations, including sugar-free, are reviewed as potential carriers for the delivery of bioactive compounds. The physicochemical properties and sensory acceptability of the functional chocolates presented are also highlighted. Finally, future perspectives, such as the use of nanotechnology to improve the bioaccessibility and bioavailability of active ingredients, as well as the need for clinical trials to validate the pharmacological effect of functional chocolates, are also discussed.

Determination of optimum ripening time in hard cooked cheeses (Reggianito type) using survival analysis statistics: Modified versus traditional cheese making technology

In this work, we determined optimum ripening time of hard cooked cheeses made by traditional technology or by an innovative process aimed at accelerating flavor formation. For that purpose, we applied survival analysis statistics. Experimental cheese making (E) included homogenization of milk fat, unpasteurized cheese milk, changes in cooking temperature, and a curd-washing step, while traditional cheese making (T) followed a classic hard-cooked cheese making. Cheeses were ripened for 215 days and samples were analyzed at 76, 112, 128, 152, and 215 days. Consumers (250) were recruited and divided into five groups of 50 consumers for each stage. At each sampling time, consumers assessed whether the sample was "under-ripe," "ok," or "over-ripe." Optimum ripening time could be estimated only for E cheeses, with a high percentage of rejection. For T cheeses, it was not possible to determine the optimum ripening time because the rejection by over-ripening was never reported. We verified consumer segmentation: a small percentage found E cheese under-ripe and a high percentage found it over-ripe. Many consumers qualified E cheeses as too spicy, especially at the end of ripening. Spicy flavor is usually perceived before than the texture and evidenced an acceleration of the flavor formation. We concluded that the innovative intervention in cheese making technology was successful in accelerating cheese ripening. It also had potential to develop a new cheese product targeted at consumers who chose/prefer good spicy flavor. PRACTICAL APPLICATION: Survival analysis is a useful methodology to determine the optimum ripening time of foods based on consumer data. In this work, it evidenced that the proposed innovative cheese making was successful in accelerating the formation of cheese flavor, and had the potential to develop a new cheese product targeted at consumers who chose/prefer good spicy flavor.

Partial replacement of pork fat by Echium oil in reduced sodium bologna sausages: technological, nutritional and stability implications

BACKGROUND

The present research aimed to evaluate the nutritional, technological, microstructural and sensory characteristics of bologna sausages made with pork fat replaced with Echium oil. Three different treatments were processed, all of them with approximately 35% less sodium than a regular bologna-type sausage: Control (only pork backfat addition) and T25 and T50 (replacement of 25 and 50% of the added animal fat with Echium oil respectively).

RESULTS

Proximate composition, texture profile analysis, fatty acid profile and microstructure were evaluated to characterize the products. In refrigerated storage, the following characteristics were assessed: thiobarbituric acid-reactive substances (TBARS) index, objective color, pH value, microbiological counts and sensory acceptance. Both samples with Echium oil (T25 and T50) showed a healthier lipid profile, with high omega-3 content, mainly from α-linolenic and stearidonic fatty acids, consequently presenting better (P ≤ 0.05) values of nutritional indices than the Control. However, the replacement of 50% animal fat with Echium oil negatively affected (P ≤ 0.05) most of the technological characteristics and the sensory acceptance of bolognas. In contrast, the treatment with 25% replacement did not show significant differences in most of the evaluated parameters compared with the Control sample.

CONCLUSION

Thus the replacement of 25% of pork backfat with Echium oil in bologna sausages can be recommended, representing a good balance between nutritional gains and sensory impairment. © 2019 Society of Chemical Industry.

Development and Sensory Shelf-Life Testing of KOKO Plus: A Food Supplement for Improving the Nutritional Profiles of Traditional Complementary Foods

BACKGROUND

Providing nutritionally adequate complementary foods is essential in preventing malnutrition in young infants. Koko made from fermented corn dough constitutes the most common complementary food in Ghana. However, these do not meet the nutrient requirements.

OBJECTIVE

To develop and test the acceptability and shelf-life of an energy-dense complementary food supplement for improving the nutritional profile of traditional complementary foods.

METHODS

Surveys of families in urban and rural communities and stakeholder engagements with health professionals were done to identify the most predominant traditional complementary foods and young infants' feeding practices. A food supplement, KOKO Plus, that would improve the nutritional profile of koko and other complementary foods needed to be developed. Linear programming was used in ingredient formulations for the food supplement based on locally available foods. The acceptability of the food supplement, KOKO Plus, in koko and soup was assessed using 14 trained assessors in a 2 × 2 crossover design. Shelf-life of the product was estimated using the difference in control sensory test method at different storage temperatures (24°C, 34°C, and 44°C).

RESULTS

Koko was the most predominant complementary food in many homes. The KOKO Plus food supplement improved the nutritional profile of koko to satisfy the nutrient intake requirements of young infants as recommended by World Health Organization. KOKO Plus was microbiologically safe, with estimated shelf-life of more than 12 months.

CONCLUSION

The development of KOKO Plus as a food supplement provides a practical solution to improve the nutritional status of weaning children in Ghana.

Effect of Different Storage Conditions on Analytical and Sensory Quality of Thermally Processed, Milk-Based Germinated Foxtail Millet Porridge

Foxtail millet porridge was prepared using germinated grains and milk and was evaluated for its storage stability after thermal processing at ultra-high temperatures (UHT) of 142 °C for 5 s and retort processing temperatures of 121.5 °C for 15 min. Various physical, chemical, and microbial changes of the porridge were studied for a storage period of 180 days at 25 ± 1 °C. Using consumer perception and survival analysis, the predicted shelf life of the UHT treated and retort processed foxtail millet porridge samples stored at 25 ± 1 °C was found to be 186 ± 9 days and 245 ± 15 days, respectively. Also, data from consumer liking, profiling, physical, chemical, and microbial parameters showed significant changes (P < 0.05) in the thermally treated packaged porridge samples over time. As the consumer overall acceptability decreased, the detection of positive attributes (thick and uniformly colored texture and appearance; grainy mouth texture; caramel taste and aroma) in the porridge decreased, while the detection of negative attributes (uneven, decolored, and curdled texture and appearance; sticky mouth texture; cooked, sour and off smell; cooked, sour and off taste) increased. The present study could establish a significant difference (P < 0.05) in the storage induced properties of UHT and retort processed porridge samples. The analytical evaluation of foxtail millet porridge found that UHT treated porridge was better in quality, but consumers preferred retort processed porridge. PRACTICAL APPLICATION: The quality and sensory attributes, evaluated for UHT treated and retort processed porridge samples during the storage period of 180 days, were found to be contradictory. Based on the results of CATA sensory analysis, the shelf life of UHT treated and retort processed porridge samples was predicted to be more than 6 months. Therefore, both UHT treatment and retort processing can be effectively applied to prepare a ready to eat milk based porridge using germinated foxtail millet grains.

Shelf-life dating of shelf-stable strawberry juice based on survival analysis of consumer acceptance information

BACKGROUND

Accurate shelf-life dating of food products is crucial for consumers and industries. Therefore, in this study we applied a science-based approach for shelf-life assessment, including accelerated shelf-life testing (ASLT), acceptability testing and the screening of analytical attributes for fast shelf-life predictions. Shelf-stable strawberry juice was selected as a case study.

RESULTS

Ambient storage (20 °C) had no effect on the aroma-based acceptance of strawberry juice. The colour-based acceptability decreased during storage under ambient and accelerated (28-42 °C) conditions. The application of survival analysis showed that the colour-based shelf-life was reached in the early stages of storage (≤11 weeks) and that the shelf-life was shortened at higher temperatures. None of the selected attributes (a^* and ΔE^* value, anthocyanin and ascorbic acid content) is an ideal analytical marker for shelf-life predictions in the investigated temperature range (20-42 °C). Nevertheless, an overall analytical cut-off value over the whole temperature range can be selected.

CONCLUSIONS

Colour changes of strawberry juice during storage are shelf-life limiting. Combining ASLT with acceptability testing allowed to gain faster insight into the change in colour-based acceptability and to perform shelf-life predictions relying on scientific data. An analytical marker is a convenient tool for shelf-life predictions in the context of ASLT. © 2017 Society of Chemical Industry.

Effect of cold chain interruptions on the shelf-life of fluid pasteurised skim milk at the consumer stage

Abstract This study aimed to verify the effect of time and temperature abuse on bacterial numbers in fluid pasteurized skim milk by simulating the real-life scenario, which usually occurs when cold chain is interrupted by consumers prior to consumption that affect the shelf-life of milk. Total three trials were carried out in this study. Thermal abuse was simulated with temperature fluctuations from 5 °C. In the first trial, the information about holding the milk samples for 8 hours at three different temperatures of 15 °C, 20 °C and 25 °C was obtained using a data logger to predict the effect of temperature abuse on the milk microbial quality. Further, in the second and third trial, the effect of temperature abuse on bacterial numbers was examined by holding milk at 5 °C and then shifts temperature to 25 °C for 8 h and 6 h. The pH was monitored during storage. The total bacterial count was examined by the Standard Plate Count (SPC). The mean air temperature had the greatest impact on milk temperature. It took 3.0 h, 3.9 h and 4.2 h to warm up when exposed to the temperatures of 15 °C, 20 °C and 25 °C, respectively. The holding time of 8 h at 25 °C showed that bacterial numbers (1 x 105 CFU mL-1) were higher after 14 days of storage, but control samples at 5 °C (< 1 x 104 CFU mL-1) were still within the acceptable level (5 x 104 CFU mL-1). A holding time of 6 h at 25 oC showed much higher bacterial numbers (1 x 109 CFU mL-1) compared to control samples (1 x 107 CFU mL-1) which were held at 5 °C for 11 days. The pH of the milk decreased with increasing bacterial growth during the extended storage time. The results show that temperature abuse has a significant effect on milk microbial stability and shelf life. It is important to maintain the milk temperature at 5 °C or less as the bacterial growth directly depend on increasing temperature and holding time, which pose the potential risk of microbial hazards leading to foodborne illness. Thus, consumers must understand the factors associated with the safe handling of milk to keep it safe to use before the expiry date.

Effects of Storage Conditions on Consumer and Chemical Assessments of Raw 'Nonpareil' Almonds Over a Two-Year Period

Abstract

Raw almonds are a major commodity, yet much is unknown about how storage conditions determine their shelf life. The storage stability, as measured by consumer assessments and chemical measures, of raw almonds was determined for samples stored in cardboard boxes and polypropylene packaging for 2 years at 4, 15, 25, and 35 °C, and at 50% and 65% relative humidity (RH). Samples stored in unlined cartons always failed (>25% rejection) before their counterparts stored in polypropylene bags under identical environmental conditions. Models determined that polypropylene packaging (as opposed to unlined cardboard cartons) extended the time until sample rejection by more than 7 months. Temperature and RH were both negatively associated with storage time until failure. Flavor was a greater contributor to consumer acceptability than texture or odor, while peroxide values and free fatty acids were of greater importance in predicting raw almond consumer quality than measures of conjugated dienes or 2‐thiobarbituric acid‐reactive substances.

Practical Application

The results of this study will allow almond producers to determine packaging types and environmental storage conditions that provide shelf life of a specified time.

Estimation of failure criteria in multivariate sensory shelf life testing using survival analysis

For most food products, shelf life is determined by changes in their sensory characteristics. A predetermined increase or decrease in the intensity of a sensory characteristic has frequently been used to signal that a product has reached the end of its shelf life. Considering all attributes change simultaneously, the concept of multivariate shelf life allows a single measurement of deterioration that takes into account all these sensory changes at a certain storage time. The aim of the present work was to apply survival analysis to estimate failure criteria in multivariate sensory shelf life testing using two case studies, hamburger buns and orange juice, by modelling the relationship between consumers' rejection of the product and the deterioration index estimated using PCA. In both studies, a panel of 13 trained assessors evaluated the samples using descriptive analysis whereas a panel of 100 consumers answered a "yes" or "no" question regarding intention to buy or consume the product. PC1 explained the great majority of the variance, indicating all sensory characteristics evolved similarly with storage time. Thus, PC1 could be regarded as index of sensory deterioration and a single failure criterion could be estimated through survival analysis for 25 and 50% consumers' rejection. The proposed approach based on multivariate shelf life testing may increase the accuracy of shelf life estimations.

The Acceptability Limit in Food Shelf Life Studies

Despite its apparently intuitive nature, the acceptability limit is probably the most difficult parameter to be defined when developing a shelf life test. Although it dramatically affects the final shelf life value, it is surprising that discussion on its nature has been largely neglected in the literature and only rare indications about the possible methodologies for its determination are available in the literature. This is due to the fact that the definition of this parameter is a consumer- and market-oriented issue, requiring a rational evaluation of the potential negative consequences of food unacceptability in the actual market scenario. This paper critically analyzes the features of the acceptability limit and the role of the decision maker. The methodologies supporting the choice of the acceptability limit as well as acceptability limit values proposed in the literature to calculate shelf life of different foods are reviewed.

Shelf life determination of sliced Portuguese traditional blood sausage--Morcela de Arroz de Monchique through microbiological challenge and consumer test

Morcela de Arroz (MA) is a ready-to-eat blood and rice cooked sausage produced with pork, blood, rice, and seasonings, stuffed in natural casing and cooked above 90 °C/30 min. It is commercialized whole, not packed, with a restricted shelf life (1 wk/0 to 5 °C). The objective of this work was to establish sliced MA shelf life considering both the behavior of L. monocytogenes through a microbiological challenge test (MCT) and the consumer acceptability of MA stored: vacuum packed (VP), modified atmosphere packed (MAP: 80% CO2/20% N2 ), and aerobic packed (AP). The MCT was conducted inoculating ±3 log CFU/g of L. monocytogenes cell suspension on the MA slices. Packaged samples were stored at 3 ± 1 °C and 7 ± 1 °C until 20 d. At 3 ± 1 °C, L. monocytogenes behavior was not affected by packaging or storage time. At 7 ± 1 °C, the pathogen increased nearly 1 log CFU/g in the first 4 d. L. monocytogenes populations in AP were higher (P < 0.05) than in MAP. The pathogen may grow to hazardous levels in the 1st days if a temperature abuse occurs. Considering the acceptability by the consumers, the shelf life of MA stored at 3 ± 1 °C was 4.4 d for AP, 8.1 d for VP, and 10.4 d for MAP. The sensory shelf life established based on sensory spoilage is shorter than the shelf life to maintain the population of L. monocytogenes in safe levels.

Predictive modelling for shelf life determination of nutricereal based fermented baby food

A shelf life model based on storage temperatures was developed for a nutricereal based fermented baby food formulation. The formulated baby food samples were packaged and stored at 10, 25, 37 and 45 °C for a test storage period of 180 days. A shelf life study was conducted using consumer and semi-trained panels, along with chemical analysis (moisture and acidity). The chemical parameters (moisture and titratable acidity) were found inadequate in determining the shelf life of the formulated product. Weibull hazard analysis was used to determine the shelf life of the product based on sensory evaluation. Considering 25 and 50 % rejection probability, the shelf life of the baby food formulation was predicted to be 98 and 322 days, 84 and 271 days, 71 and 221 days and 58 and 171 days for the samples stored at 10, 25, 37 and 45 °C, respectively. A shelf life equation was proposed using the rejection times obtained from the consumer study. Finally, the formulated baby food samples were subjected to microbial analysis for the predicted shelf life period and were found microbiologically safe for consumption during the storage period of 360 days.

How thick do consumers' want their meat and how thick do they get it? The case of deep-fried breaded beef

The main objective was to estimate the optimum thickness of meat from a consumers' perspective. Breaded beef (known as "milanesa" in Spanish speaking countries and as "schnitzels" in Austria) is a food product prepared with a slice of meat that is dipped in beaten egg to then be covered in bread crumbs; thus prepared it is fried. This product was used as a case study. Breaded beef was evaluated in three different stages: raw slice of meat, appearance of meat after frying, and during mastication. Breaded beef prepared with meat of varying thicknesses were presented to consumers who evaluated if the thicknesses were too thin, ok or too thick. Survival analysis statistics were used to estimate the optimum thicknesses. Results for each stage were: raw slice of meat = 6.7 ± 0.2 mm, appearance of the cut fried breaded beef = 8.4 ± 0.3 mm and during mastication = 7.6 ± 0.3 mm. The average thickness of the meat cut by butchers for breaded beef was 5.9 mm, not too far from the optimum. However, the average thickness of the meat in the breaded beef ready for frying sold by the same butchers 3.7 mm, clearly thinner than the optimum.

Development of functional milk desserts enriched with resistant starch based on consumers’ perception

Sensory characteristics play a key role in determining consumers’ acceptance of functional foods. In this context, the aim of the present work was to apply a combination of sensory and consumer methodologies to the development of chocolate milk desserts enriched with resistant starch. Chocolate milk desserts containing modified waxy maize starch were formulated with six different concentrations of two types of resistant starch (which are part of insoluble dietary fiber). The desserts were evaluated by trained assessors using Quantitative Descriptive Analysis. Moreover, consumers scored their overall liking and willingness to purchase and answered an open-ended question. Resistant starch caused significant changes in the sensory characteristics of the desserts and a significant decrease in consumers’ overall liking and willingness to purchase. Consumer data was analyzed applying survival analysis on overall liking scores, considering the risk on consumers liking and willing to purchase the functional products less than their regular counterparts. The proposed methodologies proved to be useful to develop functional foods taking into account consumers’ perception, which could increase their success in the market.