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The Importance of Food Quality Testing

Fruit and vegetable zone in supermarket

Scott Trimble

December 21, 2021 at 11:48 am | Updated April 14, 2022 at 10:59 am | 8 min read

Feeding the world’s growing population requires great quantities of food and accurately measuring the quality of that food is vital to sustained personal and economic health. Food quality testing is necessary to monitor and control quality parameters throughout the fresh produce supply chain to meet consumer demands and extend shelf life.

What are Food Quality Testing Parameters?

Any food attributes used to evaluate quality can be deemed quality parameters. However, quality means different things to different people in the food supply chain, so the specific parameters tested can vary.

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According to the FAO, agrifood quality implies the total characteristics that define its value and satisfy its stated needs.

The FAO finds that food quality can relate to

  • food characteristics, such as nutrition, organoleptic properties, such as taste or smell, and hygiene,
  • use qualities of convenience and conservational impact,
  • and the psychosocial qualities of satisfaction throughout the supply chain.

The standard quality parameters rely on biochemistry and probe the internal physiology of plants that is impossible to see with the human eye.

Moreover, precise food science tools are used throughout the food supply chain, which rapidly measure the quality parameters in objective and quantitative terms. These tools replace laboratory tests that previously took days to perform. The widespread use of food quality parameters is partly due to the availability of affordable, easy-to-use tools to measure them.

The United Nations recommends using the latest technology and science to reduce food loss, make agriculture sustainable, and meet the growing food needs of an increasing population.

 The following parameters are commonly used food quality testing:

  • Color and hue of the skin and inner flesh
  • Texture, which is measured as firmness
  • Sweetness is measured as soluble sugars in BRIX
  • Sourness is measured as titrable acidity. The acids evaluated will depend on the food.
  • Dry matter content, which is the total of all solids in fruits minus water.
  • Phytochemicals to establish nutritional and health benefits.
  • Toxins, like aflatoxins that indicate the safety and hygiene of the fresh produce.

These quality parameters are used alone or in various combinations depending on the needs of a stakeholder in the food supply chain.

Factors Affecting Fresh Produce Quality Parameters

Several factors influence food quality parameters, depending on the given stage of the supply chain.

Many of the following pre-harvest factors have long-lasting effects on produce quality:

  • Agricultural practices
  • Environmental conditions
  • Soil health
  • Genotype

Agricultural practices: The conditions in which crops are grown affect the plant and its productivity and product quality. Thus, food quality testing parameters will depend on crop health affected by fertilizers, irrigation, pruning, maturity at harvest, and harvest method and handling. For example, dry matter has been shown to be very responsive to agricultural practices.

Environmental conditions: Factors such as temperature, rainfall, drought, heat, and frost can cause stress that will impact crop physiology and, thus, productivity and food quality. Storms and hail will also affect quality by physically damaging vegetables and fruits. Naturally, if the environmental conditions are ideal, the quality of fresh produce will follow suit.

Soil: The type of soil, its fertility, and biodiversity are essential, especially in the case of organic cultivation.

Genotype: The cultivar can have a significant impact on fresh produce quality.

Common post-harvest factors affecting produce quality are:

  • Mechanical damage
  • Storage conditions
  • Ethylene production
  • Pest and microbial attacks

Mechanical Damage: Fresh produce is delicate. Mechanical damage due to improper handling in transport, packing houses, and storage leads to bruising. Bruising not only spoils produce appearance, but a break in the outer skin can result in microbial infections and considerable moisture loss, reducing yield. For example, a damaged apple loses 400% more moisture than intact fruit.

Storage conditions: Environmental conditions, such as temperature, relative humidity, and oxygen & carbon dioxide concentrations will affect ripening, respiration and transpiration. This will, in turn, affect how long the harvest lasts.

Ethylene production: Climacteric fruits naturally produce phytohormone ethylene to ripen. Once ethylene production starts, it can lead to over-ripening and senescence and trigger ethylene production in neighboring produce. Many non-climacteric fresh produce are also sensitive to ethylene and decay.

Pest and microbial attacks: Pests and microbes can cause physical and physiological damages. Some causal organisms may be present before harvest, but improper hygienic conditions during transport and storage can lead to considerable losses.

Figure 1: Pictures show the influence of genotype on the development of quality parameters in P. armeniaca, ” ‘GC 2-11’ and ‘GC 3-7’ analyzed in three different ripening stages including green fruit (Stage A), during color change (Stage B), and at physiological ripening (Stage C), “García-Gómez et al. 2020. Image credits: https://doi.org/10.3389/fpls.2020.01269

Measuring Food Quality Attributes

Food quality parameters are categorized as product and process attributes.

  • Product attributes can be appearance, texture, taste, smell, safety, post-harvest life, and convenience.
  • Process attributes can be the origin of the product, means of production, and environmental concerns.

Though product attributes are more often associated with end consumers, increasingly both product and process attributes are being considered by those throughout the supply chain.

…to Meet End-Consumer Preference

With color, texture, and taste being of paramount importance to end consumers in markets and grocery stores, growers and suppliers will naturally concern themselves with these attributes. Breeders, growers, and scientists will quantify and manipulate attributes using produce quality parameters such as soluble sugars, acidity, and phenols to produce desirable commodities.

Dry matter is another vital parameter that is increasingly being considered by the food industry, as it has been shown to be an accurate indicator of present and future taste in many produce commodities.

Though customers will ultimately concern themselves only with the end result of these data points, it remains vitally important for supply chain stakeholders to understand and make use of these proven indicators. Understanding how chemical composition affects the end product becomes especially important when developing and sorting produce for regions with differing taste preferences.

…to Assess Produce Maturity

Produce quality parameters are used as maturity indices, a process attribute to make harvests more predictable. Earlier farmers used subjective methods to judge whether their crop was ready for harvest. In the modern landscape, this testing largely results in economic losses, as the quality of the harvest is not able to meet market standards. These days, objective industry, national, and international standards evaluate fresh produce in terms of quality parameters. Growers use the same parameters to judge their harvest, earn more, and avoid loss due to rejection.

The following fruit quality parameters are measured by objective food science tools and used as maturity indices:

Sugar, color, and firmness are used for non-climacteric fruits, and degreening is used for citrus fruits, peppers, etc.

Dry matter content is becoming the most crucial maturity index for climacteric fruits, as it is a clear indicator of quality, which is found to have a direct relationship with dry matter content. That is, higher dry matter means higher quality. Dry matter measures starch, which later turns to sugars in climacteric fruits. Thus, dry matter measurement is able to indicate future quality and growers can be confident that if they wait until their fruits or vegetables reach the recommended dry matter content, their products will not be rejected by regulators or retailers.

…to Aid Food Processing

Food processing for the production of products like oils, juices, dry fruits, jams, alcoholic products, forages, etc. requires measurement of various food quality parameters. 

The parameters chosen for processing fruits will depend on the intended end-use. For instance, sugar content is heavily weighted when measuring fruits to make jams. The same fruit, if bound for juicing, would be assessed for both sugar and acidity.

In wine grapes, in addition to sugars and acidity, the anthocyanin and total phenols concentration is also tested because of their influence on the flavor of a wine.

Moreover, the value of each quality parameter used to accept items for fresh consumption and processing will differ, even for the same type and variety, depending on the use. This can have important implications when considering maximizing the usability of a crop, given the variation that can occur in a single field or orchard.

…for Quality Control in the Post-Harvest Supply Chain

To extend shelf-life in the post-harvest stage, the environmental factors affecting food quality are continuously monitored and controlled to reduce the potential negative impact. The most common method is to lower temperatures to decrease all physiological processes, especially respiration and ethylene production.

Sorting and culling of spoiled fruits occurs at several critical points in the supply to control ethylene production and disease.

However, dry matter, soluble sugar content, titrable acidity, and firmness are controlled to measure the quality directly. It is also necessary to measure quality parameters immediately after harvest to sort fresh produce at different stages of maturity and ripeness and decide which fruits and vegetables to market directly and which to slate for storage. New, portable devices to control quality and environmental conditions are a significant asset in this stage.

…to Improve Nutraceuticals in Fresh Produce

Natural phytochemicals with health benefits called nutraceuticals are found in most fresh produce. Some foods, however, will have more than others, making them “functional foods;” for example, antioxidants in green tea, potassium in bananas, lycopene from tomato, carotenoids from carrot, etc. In fact, olive oils are graded, in large part, based on neutraceuticals like polyphenols.

Other neutraceuticals of interest are phenols, amino acids, vitamins, antioxidants like anthocyanins, and minerals like iron, magnesium, phosphosous, manganese, etc. The main nutraceuticals tested are vitamins and antioxidants.

End-consumers are growing more conscious of the health benefits and detriments of each type of food. Hence, the food industry is focusing on improving the concentrations of relevant nutraceuticals.

Some plant products are marketed as dietary supplements due to their high nutraceutical content.  During the production of food supplements, nutraceuticals are monitored to ensure efficacy, safety, quality of raw materials, absence of contaminants, and adulteration by inappropriate substitutes.

Each relevant nutraceutical will function as a food quality parameter depending on the sought-after benefit.

…for Quality Compliance

To export and benefit from better prices, it is necessary to meet strict food quality standards set by importing countries. Several certifying agencies provide common international standards to make this process transparent. Codex Alimentarius is the basis of food standardization in the “Agreement on the Application of Sanitary and Phytosanitary Measures (SPS) of the World Trade Organization (WTO).

Quality parameters of product and process attributes define these standards. The parameters control produce size, consistency, appearance, freshness, hygiene, safety, and maturity (color, dry matter, sugar content, pH, titrable acidity, etc.). The food products are then classified depending on the percentage of requirements fulfilled.

The unique mix of fresh produce quality parameters can also specify species and variety.

Applications Of Food Quality Parameters

The ability to measure food quality parameters is vital to both the supply chain and research efforts. Using the same parameters can help in applying research results in the food chain. Frequently, the tools used are also the same, and the accuracy and reliability of modern food science tools makes them comparable to many complex laboratory procedures.

Research applications of food quality parameters:

  • Plant breeding to increase biomass accumulation, measured as dry matter.
  • Improving nutraceutical concentrations by breeding for vegetables and fruits of the required quality.
  • Developing chemometric models to predict quality with precision tools.
  • Crop breeding to enhance effectiveness of nutraceuticals.
  • Research in agricultural practices to improve quality. For example, by identifying the best pruning methods to enhance dry matter or sugar content.
  • Testing preharvest and post-harvest treatments to control infections.
  • Optimizing greenhouse and indoor farming methods.

Industry applications of food quality parameters:

  • Monitoring quality during storage and transport to help in sorting and grading fresh produce
  • Extending storage and transport time
  • Maintaining quality of fresh produce during storage
  • Assigning food prices at various points in the supply chain, from farms to retailers.
  • Drawing on nutraceutical concentrations and properties to develop pharmaceuticals and dietary supplements from plants.
  • Authentication of geographical origin, species, variety, etc.
  • Processing and quality control during wine and other alcohol production.
  • Food processing of vegetables and fruits to make ready-to-consume products, like juices, chips, etc.

Near-Infrared Spectroscopy Devices for Measuring Quality Parameters

In association with food science research and practice, a separate industrial sector is growing to develop and provide the precise devices necessary to measure and monitor various quality parameters. Near-Infrared Spectroscopy, which is ideally suited for measuring organic compounds’ quality and quantity, is by far one of the most common techniques used. Food science tools like the quality analyzers produced by Felix Instruments – Applied Food Science, are an industry standard. These devices, in conjunction with those designed for post-harvest gas analysis, are actively improving the production of fresh produce, making the way for higher profits and more sustainable practices throughout the industry.

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